llrf for the sps 800 mhz cavities g. hagmann, p. baudrenghien 12/12/2013liu meeting 1
TRANSCRIPT
LIU meeting 1
LLRF FOR THE SPS 800 MHZ CAVITIES
G Hagmann P Baudrenghien
12122013
LIU meeting 2
Block diagram12122013
LIU meeting 3
800 MHz TX-cavity chain
Cavity
12122013
Centre freq 800888 MHz
Phase advance per cell p2
Group velocity vgc +0035
Cell length 935 mm
Total length L (37 cells) 3460 m
Series impedance R2 0647 MWm
3145 MHz
2
20 2 2
2
sin sin sin2 2 22 8
2 2
1
RF b
g
g
Z R L RV L I j I
vL
v v
LIU meeting 4
800 MHz TX-cavity chain (contrsquod)
TX (IOT)
1 dB 3 MHz
-4 dB 5 MHz
12122013
Measurement reproduced from Ericrsquos presentation
Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth
Vector sum
12122013 LIU meeting 5
New 800 MHz System (VME)
LL Cavity 1 LL Cavity 2
12122013 LIU meeting 6
LL Cavity 1 LL Cavity 2LL Common
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 2
Block diagram12122013
LIU meeting 3
800 MHz TX-cavity chain
Cavity
12122013
Centre freq 800888 MHz
Phase advance per cell p2
Group velocity vgc +0035
Cell length 935 mm
Total length L (37 cells) 3460 m
Series impedance R2 0647 MWm
3145 MHz
2
20 2 2
2
sin sin sin2 2 22 8
2 2
1
RF b
g
g
Z R L RV L I j I
vL
v v
LIU meeting 4
800 MHz TX-cavity chain (contrsquod)
TX (IOT)
1 dB 3 MHz
-4 dB 5 MHz
12122013
Measurement reproduced from Ericrsquos presentation
Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth
Vector sum
12122013 LIU meeting 5
New 800 MHz System (VME)
LL Cavity 1 LL Cavity 2
12122013 LIU meeting 6
LL Cavity 1 LL Cavity 2LL Common
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 3
800 MHz TX-cavity chain
Cavity
12122013
Centre freq 800888 MHz
Phase advance per cell p2
Group velocity vgc +0035
Cell length 935 mm
Total length L (37 cells) 3460 m
Series impedance R2 0647 MWm
3145 MHz
2
20 2 2
2
sin sin sin2 2 22 8
2 2
1
RF b
g
g
Z R L RV L I j I
vL
v v
LIU meeting 4
800 MHz TX-cavity chain (contrsquod)
TX (IOT)
1 dB 3 MHz
-4 dB 5 MHz
12122013
Measurement reproduced from Ericrsquos presentation
Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth
Vector sum
12122013 LIU meeting 5
New 800 MHz System (VME)
LL Cavity 1 LL Cavity 2
12122013 LIU meeting 6
LL Cavity 1 LL Cavity 2LL Common
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 4
800 MHz TX-cavity chain (contrsquod)
TX (IOT)
1 dB 3 MHz
-4 dB 5 MHz
12122013
Measurement reproduced from Ericrsquos presentation
Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth
Vector sum
12122013 LIU meeting 5
New 800 MHz System (VME)
LL Cavity 1 LL Cavity 2
12122013 LIU meeting 6
LL Cavity 1 LL Cavity 2LL Common
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Vector sum
12122013 LIU meeting 5
New 800 MHz System (VME)
LL Cavity 1 LL Cavity 2
12122013 LIU meeting 6
LL Cavity 1 LL Cavity 2LL Common
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
New 800 MHz System (VME)
LL Cavity 1 LL Cavity 2
12122013 LIU meeting 6
LL Cavity 1 LL Cavity 2LL Common
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
New 800 MHz System (VME)
RFFGCMM SwitchampLimitCavity Loops 200MHZ
Quadrupler
Clock Distributor
Linux FrontEnd CTRV
VM
E b
us
(A2
4D
16)
RF
Lo
wL
eve
l B
ac
kpla
ne
12122013 LIU meeting 7
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
VME Cards
Switch amp Limit Clock Distributor
RF design amp FPGA (Controls Acquisitionshellip) on the same board
12122013 LIU meeting 8
JLollierou JNoirejan GHagmann
GHagmann
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
VME Cards
200MHZ Quadrupler
12122013 LIU meeting 9
RF Function generator
MNaon TLevens GHagmann
GHagmann
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
12122013 LIU meeting 10
3rd HiLumi LHC-LARP
SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits
RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz
4x
LO Distribution
2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)
SRAM 2x8 Mbyte for diagnostics
VME P1 backplane
for slow controlsread
out
Dedicated backplane (P2)
bull Power Supplybull Clocksbull Interlocksbull hellip
Xilinx Virtex-5 SXT
G Hagmann BE-RF-FBdesigner
Cavity Loops v1
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Module Name Status 122012 Status 122013 Software
Linux Front-end (CPU)
Installed Installed NR
CTRV (timing) Installed Installed OK
CMM(Crate Management)
Installed Installed OK
WBS(Wide Band Switch)
LHC Spares available LHC Spares available -
RFFG(Function generator)
under design Installed OK
SwitchampLimit Proto V2 under test V3 pre-series in prod From L4
Clock Distributor Proto V2 under test Proto V3 under test From L4
200MHz Quadrupler Proto V1 in prod V2 in prod NR
Cavity Loops(RF Feedback)
Under design V1 available From L4
Veto Sum Under specification Under specification -
Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR
Status
12122013 LIU meeting 11
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Cavity Loop IQ demodulationTWC 800 MHz Frequencies
LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz
Fs
12122013 LIU meeting 12
Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits
The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Fine delay(1 Turn)
RF Function Receiver(VoltagePhase offset Setpoint)
Longitudinal Damper(From Beam Control Optical Gbit link)
Ref Phase from 200MHz Cavity Σ
Comb filter(Beam synchronous
clock)
Cavity filter(Absolute Cavity
response)
Feed forward(Beam synch clock)
Polar Loop
In-situ Observation
ampBBNANoise
(Blow-up)
RF Modulator(Single side band Transmitter)
12122013 LIU meeting 13
Ref Phase 200MHz Cavity Σ + setPoint
Comb filter=gt Gain plusmn n∙frev plusmn m∙fs
Cavity filter=gt Sign Inversion
cavity zeros
FiFo1T-delay
NCOupampdown Modulation
RF Modulator
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
TWC 200 MHz Phase ΣφsetPoint
4x TWC200 Σ
TWC800
Bunch lengthening Bunch shortening
12122013 LIU meeting 14
TWC200 Σ
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Filters (implementation)
Beat frequency computation (from pre-defined function)
Downup modulation
12122013 LIU meeting 15
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Mid-1980s Comb filter12122013 LIU meeting 16
bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches
bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)
bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHz
bull Fixed target Q26 fs lt 14 kHz
bull LHC ion 12inj Q20 fs lt 22 kHz
bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)
bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive
1
1
with
NN
ck
rev
aH z G z
a z
fN
f
3 1
3dB
rev
fG
f Conclusion The
simple IIR filter cannot be used
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
A Modern Comb filter12122013 LIU meeting 17
bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS
bull Step3 Interpolating LPF
119867119888119900119898119887 (119911 )=sum119899=0
119871minus1
119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896
119877 ∙ 119891 119903119890119907
119867 119897119901 (119911)=sum119899=0
119875minus 1
119887119897119901 ∙ 119911minus119899
FIFO N=462
The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)
36 dB stopband attenuation
6 kHz 2-sided BW around the frev lines
8 MHz single-sided -3 dB BW
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Cavity filter
bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency
bull We will compensate this with an all-pass filter with zeros at these frequencies
bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)
Freq
Fcav800888MHz
~32MHz
Frf flat top~8016MHz
∆f=+071MHz
Frf flat botom~7998MHz
∆f=-112MHz
12122013 LIU meeting 18
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous
clockbull We compensate this by
1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating
∆f
F
down modulation with ∆f
F
FilteringBefore Filtering
F
Up modulation with ∆f
∆f
After Filtering
12122013 LIU meeting 19
∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)
But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)
A candidate sign-flipping filter
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 20
RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)
and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output
bull Modulation of the 800 MHz can be applied at the set-point level
bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable
12122013
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 21
Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for
generation of the clocks
bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only
bull The tracking of the 200 MHz phase must be studied
12122013
Sawtooth
Frf200
Frf avg (ions)
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 22
Planningbull The two cavities are equipped with antenna on all cells
bull 1 antenna per cell
bull The Antenna Summing network is being designedbull Help from D Valuchbull Prototype beginning of 2014
bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014
bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)
bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam
during SPS hardware commissioning at start-up
12122013
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 23
Thank you for your attentionhellip
12122013
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 24
References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985
[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001
[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010
[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011
[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996
[6] P Baudrenghien CAS RF 2000 and 2010
12122013
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
LIU meeting 25
Back-Up slides
12122013
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-
CavityLoop Up-modulationRF Modulation SSB 16Bits DACs
12122013 LIU meeting 26
Low phase noise(LO from Agilent E8663B still)
Span 20MHzSFDR gt 100dB
∆ +- 1deg∆G +- 05dB
phase
Gain
- LLRF for the SPS 800 MHz cavities
- Block diagram
- 800 MHz TX-cavity chain
- 800 MHz TX-cavity chain (contrsquod)
- Vector sum
- New 800 MHz System (VME)
- New 800 MHz System (VME) (2)
- VME Cards
- VME Cards (2)
- Slide 10
- Status
- Cavity Loop IQ demodulation
- Slide 13
- TWC 200 MHz Phase Σ
- Filters (implementation)
- Mid-1980s Comb filter
- A Modern Comb filter
- Cavity filter
- Cavity filter (in baseband)
- RF ON-OFF Modulation
- Operation with Ions (preliminary)
- Planning
- Thank you for your attentionhellip
- References
- Back-Up slides
- CavityLoop Up-modulation
-