fluctuations and noise (spie) 5/28/041 centro astronómico de yebes, obs. astronómico nacional, ign...

Fluctuations and Noise (SPIE) 5/28/04 1Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain)

Experimental results of gain fluctuations and noise in microwave low-noise

cryogenic amplifiers

Juan Daniel Gallego, Isaac López-Fernández,Carmen Diez, Alberto Barcia

Centro Astronómico de YebesObservatorio Astronómico Nacional

Apartado 148, 19080 Guadalajara, SPAIN


Contents

Introduction Noise Measurements Gain Fluctuation Measurements Experimental data and results

Device Technology Temperature Statistical Analysis Bias conditions

Conclusions


Introduction: Cryogenic Amplifiers

Cryogenic Receivers: Space communications Radioastronomy

60s: Maser, Parametric (18 K @ 8.45 GHz in 1964, JPL) 70s: GaAs FET amplifiers (13 K @ 1.3 GHz in 1979, NRAO) 80s: GaAs HEMTs ( 5.5 K ! @ 8.5 GHz in 1988, GE-

NRAO) 90s: InP HEMTs (4.6 K @ 8.5 GHz in 1999, ETH-CAY)

(3.0 K @ 8.5 GHz in 2002, TRW-CAY)(2.0 K ! @ 4-8 GHz in 2002, TRW-

CAY)

Higher frequencies: SIS, HEBs


Interstage matching circuits

MICROTECHDC connector

SMA connector

Bias cavity with biasing circuits

Transistor area detail.See sourceinductive feedbackand drainresistive loading

ETH transistorwith bonding wires

1 2 3

Input matching circuit Output matching circuit


Introduction: Transistor characterization

Cryogenic S parameter measurements to model devices In-house test fixture with microstrip lines to allow two-tier TRL calibration Device measured with bonding wires DC and coldFET complete the small signal model

Noise model according to Pospieszalski The noise measured in a wide band test amplifier sets the TD of the model


EXAMPLE OFCRYOGENIC

S PARAMETERS(1 – 40 GHz)

MODEL Circuit modelMEAS Raw dataMEASG Time domain

filter


Introduction: Radiometer Sensitivity

Radiometer model

Radiometer sensitivity

Radiometer

rf

rf

out

out

rarfout

G

G

B

k

P

P

TTBGKP

)(

BfG

fS

Bf

V

fS gv

,)(21

)()(

02

0


Introduction: Gain Fluctuations

dS

2

2

42

)(

)(sin4)()(


Introduction: Specs of Gain Fluctuations

HERSCHEL: Far Infrared and Submillimeter 3.5 m Telescope orbiting in L2 with 3 cryogenic

instruments HIFI: Heterodyne Instrument for the Far Infrared with 7 dual polarization

submillimeter SIS and HEB receivers Our contribution: low noise, wide band 4-8 GHz cryogenic IF preamplifiers Sensitive parameters:

Gain fluctuations: impact in the chopping frequency

HzHz

Gn [email protected] 4

HzHz

Gn [email protected] 5

ALMA: Atacama Large Millimeter Array (USA, Europe, Japan), 64 Antennas, 35-850 GHz Our contribution: 4-8 , 4-12 GHz cryogenic IF preamplifiers

Fluctuations and Noise (SPIE) 5/28/04 10

Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain)

Introduction: Gain Fluctuations dependence

Improvements in Noise Shorter gate length HEMTs InP substrate Cryogenic Temperature

Improvements in Gain Stability Larger gate area Non HEMT GaAs substrate Ambient Temperature

Conclusion: Advances in the reduction of Noise Temperature have contributed to

increase Gain Fluctuations



Noise Measurements (1)

Room temperature methods:

Hot/cold loads Diode noise sources

Cryogenic temperature methods:

Hot/cold loads Diode noise sources Variable temperature cryogenic load Diode noise source and cold attenuator




15 K

65 K

297 K

PREAMPLIFIER

DEWAR

HPIBRS-232

NARDA DC-BLOCK

NARDA ATTEN. (15 dB)

HEMT AMPLIFIER

TEMP. SENSOR

LAKE SHORE CRYOGENIC

THERMOMETERCOMPUTER

NOISE FIGURE METER

TEST SET

SYNTHESIZER OSCILATOR

NOISE DIODE HP 346 C

Cold Attenuator Method




Cold Attenuator Method: Advantages:

Reduces the error caused by transitions Minimizes sensitivity to changes in reflection of noise source Allows fast sweep measurements in automatic systems Takes advantage of features of existent Noise Figure Meters

Disadvantages: Needs careful calibration of noise source, lines, attenuator

Accuracy: Repeatability: ± 0.2 K Absolute Accuracy: ± 1.4 K




Error Budget in Cryogenic Measurements

(f=8 GHz, TN=4 K, G=30 dB)

SOURCE OF ERROR CONTRIBUTIONCalibration of Noise Source 0.77 K

Calibration of cold attenuator 0.54 K

Calibration of temperature sensor 1.00 K

All other 0.34 K

_______________________________________________________

TOTAL (RSS) ±1.40 K



Gain Fluctuation Measurements (1)

Origins External

Power supply Temperature variations Microphonics

Internal Intrinsic to the devices

Typical Spectrum

f

HzbfS

1)(




10-2 10-1 100 10110-5

10-4

10-3

10-2

YCF 6001 Gain fluctuations Spectrum14 K Vd1=0.85 V Vd2=0.5 V Id1,2=3 mA

G

/G

[Hz-1

/2]

Freq. [Hz]

measured fitted correction




a 2.219 1010 b 1.386 10

8 c 4.184 1011 Fit: h a

1 b c

0.1 1 10 1001 10

10

1 109

1 108

1 107

MODULE ALLAN VARIANCE

OAVAR_G calm

h m a b c cal_g m

m

0.59 8.574 105

Fit: h f( ) f

0.01 0.1 1 101 10

5

1 104

1 103

0.01MODULE SPECTRUM

spn_Gcalk

h f k cal_g f k

f k

a 6.097 109 b 9.063 10

9 c 1.833 109 Fit: h a

1 b c

0.1 1 10 1001 10

10

1 109

1 108

1 107

MODULE ALLAN VARIANCE

OAVAR_G calm

h m a b c cal_g m

m

0.633 8.608 105 Fit: h f( ) f

0.01 0.1 1 101 10

5

1 104

1 103

0.01MODULE SPECTRUM

spn_G calk

h f k cal_g f k

f k



Experimental data and resultsParameters with impact in noise and fluctuations

Frequency band Device technology

Semiconductor material: InP vs GaAs Passivation:

Better noise results with unpassivated devices Gate geometry:

Gain fluctuations improve with larger gate area

Operating temperature Illumination:

Necessary to avoid carrier freezing effect in old devices, nowadays noise temperature is immune or improves with light in InP devices

Gain fluctuations worsen with illumination



Experimental data and resultsFrequency band

Noise temperature decreases with frequency:

TN [K] ~ ½ f [GHz]

Low frequency gain fluctuations are insensitive to frequency band Results of table are

contaminated by other parameters (bias, device type)

BAND NOISE GAIN GAIN FLUCTUATIONS AMPLIFIER

[GHz] STAGES DEVICES

[K] [dB] b [Hz-1/2] α

YCA 2 4 - 8 3 2 × NGST CRYO4 3.5 39.2 7.8E-5 0.64

YXF 0 8-12 2 NGST 160 + FHX13X 6.5 21.9 10E-5 0.58

YK22 18 - 26 3 NGST CRYO3 + 2 × NGST 160 8.9 26.1 13E-5 0.43

0 5 10 15 20 25 300

2

4

6

8

10

12

14

CAY LNAs noise

0.5 K/GHz

Noi

se T

empe

ratu

re [

K]

Frequency [GHz]



Experimental data and resultsDevice technology and Temperature (1)

0 100 200 3000

10

20

30

40

50

60

Room vs Noise Temperature (YCF 004)

Tn

(K)

Tamb (K)

TRW T-42 CRYO3 200×0.1 μm gate

TRW T-45 CRYO4 200×0.1 μm gate Used in DMs Space qualifiable, to be used in FMsCHOP developed

ETH T-35 200×0.2 μm gate Experimental transistor Design by request Used in MPAs

0.22 mm

0.2

mm

3 4 5 6 7 8 90

5

10

15

20

25

30

ETH T-35 TRW T-45 TRW T-42

YCF 2 InP devices comparisonOptimum noise bias

MGFC 4419 (GaAs)

Ga

in (

dB

)

Freq. (GHz)

0.0

2.5

5.0

7.5

10.0

12.5

15.0

MGFC 4419 (GaAs)

Tn

(K

)

ETH T-35 TRW T-45 TRW T-42



Experimental data and resultsDevice Technology and Temperature (2)

10-2 10-1 100 10110-5

10-4

10-3

10-2

T=297 K

T=14 K

YXV 005

InP LNA Gain Fluctuation Spectrum

Gn/

Gn

[Hz-1

/2]

Freq. [Hz]

10-2 10-1 100 10110-5

10-4

10-3

10-2

T=297 K

T=14 K

YXV 001

GaAs LNA Gain Fluctuation Spectrum

Gn/

Gn

[Hz-1

/2]

Freq. (Hz)

DEVICES NOISE TEMPERATURE [K] GAIN FLUCTUATIONS [ HZ-1/2]

TECHNOLOGY MODEL 297 K 14 K VARIATION 297 K 14 K VARIATION

GaAs FHX13X 200×0.25μm 99 13.6 ÷ 7.3 2.0E-5 3.4E-5 × 1.7 NGST 160 160×0.1μm 96 6.5 ÷ 14.8 (1.3E-5) 9.4E-5 × (7.2)

InP ETH 200 200×0.2μm 108 6.7 ÷ 16.1 (1.0E-5) 7.0E-5 × (7.0)

GaAs – InP Variation [times] None ÷ 2.1 – ÷ (1.7) × 2.8 –



Experimental data and resultsStatistical Analysis: Results of long series (1)

Analyzed two series of 9 and 10 state-of-the-art 4-8 GHz cryogenic amplifiers designed and built at CAY with microstrip hybrid technology: Development models for Herschel space telescope (all cryogenic LNAs for HIFI)

2 stages of InP NGST transistors Design constrained by space qualification

Pre-production phase of ALMA (cryogenic LNAs for the European contribution) 3 stages of InP NGST and ETH transistors. Based on HIFI design, with more degrees of freedom




3 4 5 6 7 8 90

2

4

6

8

10

12

14

16

No

ise

Te

mpe

ratu

re [

K]

f [GHz]

0

5

10

15

20

25

30

35

40

HIFI IF1 DMs9 amplifiers, P

D=4 mW, T=14 K, NGST

Ga

in [

dB]

3 4 5 6 7 8 90

2

4

6

8

10

12

14

16

No

ise

Te

mpe

ratu

re [

K]

f [GHz]

0

5

10

15

20

25

30

35

40

ALMA prototypes (YCA 2)10 amplifiers, P

D=9 mW, T=14 K, NGST+ETH

Ga

in [

dB]




Mean values of noise and fluctuations are similar in both series Excellent repeatability in noise and gain Greater dispersion of gain fluctuations results (value @ 1 Hz and spectral index) HIFI dispersion in fluctuations significantly wider than ALMA

Bias conditions homogeneous for both series Different transistor batch used for each series of amplifiers

Some transistor batches exhibit high scattering of gain fluctuations within devices of the same batch not shown in noise results

Observed also a significant batch to batch variation



Experimental data and resultsBias Conditions (1)

Tested the variation of gain fluctuations and noise with Vd, Ido Found a steep change in gain fluctuations around 0.4-0.5 Vo Noise (and gain) are much more insensitive to bias changeso High fluctuation zones could be avoided

with no penalty in noise or gain Gain fluctuations when Id

YCA 1001 Gain fluctuationsLED OFF, T=14 K

0.0E+00

2.0E-05

4.0E-05

6.0E-05

8.0E-05

1.0E-04

1.2E-04

1.4E-04

1.6E-04

1.8E-04

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65

VdT [V]

G

/G @

1 H

z [1

/Hz1

/2]

Id=3 mAId=4 mAId=5 mAId=6 mA

3,002,75

7,00

7,00

2,50

1 2 3 4 5 6 7 8 9 100,0

0,2

0,4

0,6

0,8

1,0

1,2

Noise Temperature @ 7 GHz [K]YCA 1003

2,502,753,003,253,503,754,004,254,504,755,005,255,505,756,006,256,506,757,00

Id [mA]

Vds

[V]



Experimental data and resultsBias conditions (2)

Tested also fluctuations of gate voltage with HP35670A Found similar bias dependence

Simple measurements of voltage fluctuations may help detecting sensitive bias regions

Correlation with gain fluctuations for different devices useful for pre-selecting least fluctuating devices from a batch

0,2 0,3 0,4 0,5 0,6 0,7 0,80,00

2,50x10-5

5,00x10-5

7,50x10-5

1,00x10-4

1,25x10-4

1,50x10-4

Gain fluctuations measurement noise floor

YCF 6001 1st stage fluctuationsLED OFF, 14 K Id=3 mA

VD1

(device) [V]

G/G

@1

Hz

[1/H

z1/2]

0,0

1,0x10-5

2,0x10-5

3,0x10-5

4,0x10-5

5,0x10-5

6,0x10-5

VG @

10

Hz

[V/H

z1/2]

1st stage

2nd

stage

100

101

102

10n

100n

1µ

10µ

100µ

1m

10m

YCF 6001 VG fluctuations Spectrum

8 GHz, 14 K, Vd1=0.85 V, Vd2=0.5 V, Id1,2=3 mA

VG [V

/Hz

1/2]

Freq. [Hz]

10 Hz

10-2 10-1 100 10110-5

10-4

10-3

10-2

YCF 6001 Gain fluctuations Spectrum8 GHz, 14 K Vd1=0.85 V Vd2=0.5 V Id1,2=3 mA

G/G

[H

z-1

/2]

Freq. [Hz]

measured fitted correction

1 Hz



Conclusions

The reduction in noise and the increase in bandwidth of modern cryogenic amplifiers have made more prominent the problem of gain fluctuations

The reduction of gain fluctuations is possible with an adequate selection of devices and bias

Lack of theoretical model for gain fluctuations of cryogenic amplifiers



END

fluctuations and noise (spie) 5/28/041 centro astronómico de yebes, obs. astronómico nacional, ign...

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