nanometer cmos goes millimeter wave - core nanometer cmos goes millimeter wave 2 overview ... ref....

Nanometer CMOS goes Nanometer CMOS goes millimeter wavemillimeter wave

N.DefermN.Deferm, , P.ReynaertP.Reynaert

09/07/200909/07/2009 Nanometer CMOS goes millimeter waveNanometer CMOS goes millimeter wave 22

OverviewOverview

IntroductionIntroductionActive devicesActive devicesMatchingMatchingExamplesExamplesConclusionConclusion


OverviewOverview



IntroductionIntroductionSurveillanceSurveillance

/security/security

Medical Medical ImagingImaging

Guiding ofGuiding ofvehiclesvehicles


IntroductionIntroductionAll nice and fancy applications, but letAll nice and fancy applications, but let’’s get to the s get to the serious part of the story: serious part of the story:

Design of mm-wave integrated circuits

CMOS integrated circuits for mmCMOS integrated circuits for mm--wave applications:wave applications:Analog, Digital and RF circuits on the same dieAnalog, Digital and RF circuits on the same dieSize and cost reduction for large volumesSize and cost reduction for large volumesNew mmNew mm--wave system topologies are becoming wave system topologies are becoming possible, e.g. complete beam forming architecturepossible, e.g. complete beam forming architecture


Fully integrated systemFully integrated systemUse CMOS to reduce the size & costof mm-wave mass-volume electronics


Fully integrated systemFully integrated system

Fully integrated beam forming transceiver @ mm-wave frequencies is becoming possible


OverviewOverview

IntroductionIntroductionActive devicesActive devicesPassive devicesPassive devicesExamplesExamplesConclusionConclusion


CMOS goes mmCMOS goes mm--wavewaveITRS roadmap for fTMeasured values of fmax

CMOS becomes a mm-wave technology?

Yes, but with a very high integration density

Waf

er s

ize

Inte

grat

ion

dens

ity


MOS fMOS ftt and fand fmaxmax

90nm CMOS transistor90nm CMOS transistor

Next technology nodes will reach even higher Next technology nodes will reach even higher frequencies and gain.frequencies and gain.

Masongain = 10db @ 100GHz

ft = 130GHz

fmax = 260GHz


MOS fMOS ftt and fand fmaxmax

fftt = frequency at which current gain equals unity => |h= frequency at which current gain equals unity => |h2121|=1|=1

( )in gs gs gdi v j C Cω= ⋅ +out gs mi v g≈ ⋅

( )2m

tgs gd

gfC Cπ

=⋅ +

ffmaxmax = frequency at which power gain equals unity= frequency at which power gain equals unity

8t

maxg gd

ffr Cπ

≈⋅ ⋅

Definition fmax: Ref. W. Sansen: analog design essentials, p.33

Push fmax towards higher frequencies by reducing rg


0.350.35µµm bipolarm bipolar transistortransistor

fftt is higher compared to CMOS, but fis higher compared to CMOS, but fmaxmax is is lower.lower.

Bipolar fBipolar ftt and fand fmaxmax

Masongain = 7db @ 100GHz

ft = 250GHz

fmax = 210GHz


Bipolar fBipolar ftt and fand fmaxmaxfftt = frequency at which current gain equals unity => |h= frequency at which current gain equals unity => |h2121|=1|=1

1in be

be

i v j C

v j Cr

μ

ππ

ω

ω

= ⋅ ⋅

⎛ ⎞ + ⋅ ⋅ +⎜ ⎟

⎝ ⎠

out be mi v g≈ ⋅

( )2m

tgfC Cμ ππ

≈⋅ +

ffmaxmax = frequency at which power gain equals unity= frequency at which power gain equals unity

8t

maxb

ffr Cμπ

≈⋅ ⋅

Definition fmax: Ref. W. Sansen: Analog Design Essentials, p.43

reducing rb by increasing emitter length => Cµ increases => fmax is not improving


CMOS vs. bipolarCMOS vs. bipolarComparison at equal power Comparison at equal power consumption of 4mWconsumption of 4mWMOS (W=15MOS (W=15µµm)m) => fmax => fmax from 100GHz to 260GHz from 100GHz to 260GHz when decreasing rwhen decreasing rgg. . (260GHz is maximum (260GHz is maximum achievable)achievable)Bipolar => fmax from Bipolar => fmax from 210GHz to 170GHz when 210GHz to 170GHz when decreasing rdecreasing rbb. (210GHz is . (210GHz is maximum achievable)maximum achievable)

fmax MOS can be pushed towards higher frequencies

fmax bipolar

fmax MOS


Transistor behaviorTransistor behaviorGGmaxmax vs. U: how to get the maximal out of the vs. U: how to get the maximal out of the transistor?transistor?U: measure for U: measure for maximum maximum achievable gainachievable gainGGmaxmax: actual gain of : actual gain of the transistorthe transistor

unconditionally stable region

conditionally stable region

Goal: shift stability break point towards wanted frequency of operation


Transistor behaviorTransistor behavior

Increase U, fmax and stability break point by reducing gate resistance

Increase Gmax by tuning the gate-drain capacitance

Gain increase from 0dB to 11dB @ 100GHz by the use of circuit techniques.

Note: power consumption is kept constant @ 4mW


Transistor behaviorTransistor behavior

Lowering base resistance results in a decrease of U and fmax due to increase of Cµ.

Gain loss from 6dB to 4dB@ 100GHz. Highest gain achieved with minimal size transistor.

Note: power consumption is kept constant @ 4mW


OverviewOverview



MatchingMatchingTuning of input/output capacitors reveals resistors.Tuning of input/output capacitors reveals resistors.Maximize power transfer from source to device and from Maximize power transfer from source to device and from device to load by power matching.device to load by power matching.

RRss = r= rggRRloadload = r= rdsds

Tuning elements can be included in the matching Tuning elements can be included in the matching network.network.

Ls tunes Cgs

Lload tunes Cds


MatchingMatchingHow to tune the gateHow to tune the gate--drain capacitance?drain capacitance?Differential design: Differential design:

Put negative capacitors in Put negative capacitors in parallel = wideband tuning.parallel = wideband tuning.Better noise performance Better noise performance when integrated with when integrated with digital circuits.digital circuits.

Other advantages:Other advantages:New opportunities for New opportunities for matching networks are matching networks are created.created.

Cross coupled transistor pair with Vgs = 0V to tune Cgd


TransformersTransformersIntegrated transformers Integrated transformers in 90nm CMOS:in 90nm CMOS:

Minimum insertion loss Minimum insertion loss lower than 1dB.lower than 1dB.Easy DC biasing and Easy DC biasing and connect supply voltages.connect supply voltages.Inherent DC blocking Inherent DC blocking ability.ability.Can be used to connect Can be used to connect differential networks to differential networks to other differential networks other differential networks and single ended ones.and single ended ones. Ref: D. Chowdhury et. al., IEEE ISSCC 2008

40µm

8µm


Transformers and Transformers and matchingmatching

Adaptation of size and shape can create the Adaptation of size and shape can create the ability of impedance transformation.ability of impedance transformation.

Stage 1

Stage 2

Gate bias stage 2: connected to inner coil center tap

Supply voltage stage 1: connected to outer coil center tap

Local ground stage 1

Local ground stage 2

55µm

110µm


OverviewOverview



Example 1: 60 GHz VCOExample 1: 60 GHz VCO570 um

620 um

90nm CMOS

Area: 0.35 mm2 includingprobe-padsTuning range: 61.1-66.7GHz Phase noise @ 1MHz from64GHz: -95dBc/HzPower consumption: 3.16mW@ 0.6V supply


Example 2: Differential Example 2: Differential 60 GHz PA60 GHz PA

Area: 0.25 mm2 including probe-padsGain: 7.7dB @ 48GHzPower consumption: 100mW @ 1V supply

Output power: 12.3dBm3dB BW: 22GHz (43-65GHz)


Example 3: Differential Example 3: Differential 100 GHz amplifier100 GHz amplifier

Input stage DC pads Interstage DC pads Output stage DC pads

RF input

RF output

650µm

1.4mmArea: 0.84 mm2 including probe-padsPower consumption: 50mW @ 1V supply

Gain: 15dB @ 92 GHz3dB BW: 15GHz (87-102GHz)

Simulation results


Example 4: 410 GHz Example 4: 410 GHz pushpush--push oscillatorpush oscillator

CMOS world record at 410 GHz

200 GHz higher than existingCMOS record.100 GHz higher than highperformance expensive indiumphosphide chips.

45nm CMOS 410 GHz push-pushoscillator operating at 2nd harmonic.


OverviewOverview



ConclusionConclusionCMOS will play an important role in mmCMOS will play an important role in mm--wave wave imaging applications (large volumes needed).imaging applications (large volumes needed).CMOS is very flexible from circuit design point of CMOS is very flexible from circuit design point of view: reasonable gain feasible at mmview: reasonable gain feasible at mm--wave wave frequencies by employing circuit techniques.frequencies by employing circuit techniques.Differential design creates numerous Differential design creates numerous advantages including new tuning and matching advantages including new tuning and matching techniques.techniques.Full integration of complete mmFull integration of complete mm--wave systems wave systems becomes possible.becomes possible.

nanometer cmos goes millimeter wave - core nanometer cmos goes millimeter wave 2 overview ... ref....

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