1、 2024 IEEE International Solid-State Circuits ConferenceFundamentals ofContinuous-Time ADCsShanthi PavanNT Alexander Institute Chair ProfessorIndian Institute of Technology,Madrasshanthiee.iitm.ac.in1S.PavanFundamentals of Continuous-Time ADCs 2024 IEEE International Solid-State Circuits ConferenceO

2、utlineSampling,quantization,and A/D conversionWhat is a continuous-time(CT)ADC?CT-Pipeline ADCsCT delta-sigma&CT-MASH ADCsSummary and conclusionS.PavanFundamentals of Continuous-Time ADCs2 2024 IEEE International Solid-State Circuits ConferenceSampling:Idea“Slow”signal can be recovered from samples

3、S.PavanFundamentals of Continuous-Time ADCs3Guess the signal?ty 2024 IEEE International Solid-State Circuits ConferenceSampling:Idea“Slow”signal can be recovered from samples S.PavanFundamentals of Continuous-Time ADCs4ty 2024 IEEE International Solid-State Circuits ConferenceNyquist Sampling Theore

4、m Signal bandwidth B sampling rate(=fs)2BInputSampledS.PavanFundamentals of Continuous-Time ADCs5 2024 IEEE International Solid-State Circuits ConferenceNyquist Sampling Theorem Signal bandwidth B sampling rate(=fs)2BInputSampledS.PavanFundamentals of Continuous-Time ADCs5 2024 IEEE International So

5、lid-State Circuits ConferenceQuantizationNonlinear,memoryless operationvn can be represented in digital formen=vn-yn quantization errorWhen not overloaded|e|40dB 2024 IEEE International Solid-State Circuits ConferenceAnti-Alias FilterSmall OSR Easy sampler,difficult filterHigh OSR Easy filter,diffic

6、ult samplerWide bandwidth input OSR small(technology-limited fs)S.PavanFundamentals of Continuous-Time ADCs13 2024 IEEE International Solid-State Circuits ConferenceSignal ChainSampler and quantizer ADCDiscrete-time ADCs switched-capacitor techniquesWhat are the problems?S.PavanFundamentals of Conti

7、nuous-Time ADCs14 2024 IEEE International Solid-State Circuits ConferenceNyquist-Rate ADCs:TechniquesDiscrete-time Pipeline or SAR ADCMature technologySwitched-capacitor techniques First Sample input on a capacitor Next Quantize the sampled inputS.PavanFundamentals of Continuous-Time ADCs15 2024 IEE

8、E International Solid-State Circuits ConferenceDT-ADC Front EndS.PavanFundamentals of Continuous-Time ADCs16Sampling phase(ps)Input sampled on CProcessing phaseReset phase(pr)C is reset 2024 IEEE International Solid-State Circuits ConferenceDT-ADC Front End:Sampling PhaseSwitched-capacitor input:ver

9、y difficult to driveS.PavanFundamentals of Continuous-Time ADCs17 2024 IEEE International Solid-State Circuits ConferenceDT-ADC Front EndSolutionDrive buffer Higher supply Power Adds noise Adds distortionS.PavanFundamentals of Continuous-Time ADCs18 2024 IEEE International Solid-State Circuits Confe

10、renceDT-ADCs:Summary of ChallengesSwitched-capacitor input loadHigh power on-chip bufferNeeds a higher supply voltageAdds noise and distortionOther challengesArchitecture specificAmplifier settling(pipeline),interleaving artifacts(TI-SAR)Currently addressed by extensive digital calibrationS.PavanFun

11、damentals of Continuous-Time ADCs19 2024 IEEE International Solid-State Circuits ConferenceWhat is a Continuous-Time ADC?An ADC is a CT-ADC if Inherent anti-aliasing Filter+ADC in one unit Easy to drive No spike currents drawn from input Drive buffer not neededS.PavanFundamentals of Continuous-Time

12、ADCs20 2024 IEEE International Solid-State Circuits ConferenceSimple-Minded CT-ADCFilter+Buffer+DT-ADC packaged in a boxInherent anti-aliasing FilterEasy to driveS.PavanFundamentals of Continuous-Time ADCs21 2024 IEEE International Solid-State Circuits ConferenceCT-ADC:JargonInput is filtered,sample

13、d and quantizedFilter TF Signal Transfer Function(STF)Q.noise to output TF Noise Transfer Function(NTF)S.PavanFundamentals of Continuous-Time ADCs22 2024 IEEE International Solid-State Circuits ConferenceCT-ADC:JargonSTF H(s)(this is a CT transfer function)NTF 1 (this is a DT transfer function)Any C

14、T-ADC has STF and NTFS.PavanFundamentals of Continuous-Time ADCs23H(s)2024 IEEE International Solid-State Circuits ConferenceRecall:OSR and Order TradeoffS.PavanFundamentals of Continuous-Time ADCs24Butterworth mag.responseAlias-band attenuation 40dB 2024 IEEE International Solid-State Circuits Conf

15、erenceButterworth mag.responseAlias-band attenuation 40dBRecall:OSR and Order TradeoffS.PavanFundamentals of Continuous-Time ADCs25We begin with thelow OSR case 2024 IEEE International Solid-State Circuits ConferenceFilter TradeoffsHigh order:More biquadsEach biquad adds noise and distortion What ar

16、e the tradeoffs?S.PavanFundamentals of Continuous-Time ADCs26 2024 IEEE International Solid-State Circuits ConferenceFilter Order:ResponseS.PavanFundamentals of Continuous-Time ADCs27 2024 IEEE International Solid-State Circuits ConferenceFilter Order:NoiseS.PavanFundamentals of Continuous-Time ADCs

17、28 2024 IEEE International Solid-State Circuits ConferenceFilter Order and Noise For 1 biquad Noise=X Power=P Area=A 40 dB/decadeS.PavanFundamentals of Continuous-Time ADCs29 2024 IEEE International Solid-State Circuits ConferenceFilter Order and Noise For 1 biquad Noise=X Power=P Area=A 40 dB/decad

18、e For n biquads 40n dB/dec Need noise X at output Each biquad noise=X/n Each biquad power=nP Filter power=n2P Filter area=n2AS.PavanFundamentals of Continuous-Time ADCs29 2024 IEEE International Solid-State Circuits ConferenceFilter Order and Noise For 1 biquad Noise=X Power=P Area=A 40 dB/decade Fo

19、r n biquads 40n dB/dec Need noise X at output Each biquad noise=X/n Each biquad power=nP Filter power=n2P Filter area=n2AKey TakeawayFor same noise,n biquads needn2times the power and areaS.PavanFundamentals of Continuous-Time ADCs29 2024 IEEE International Solid-State Circuits ConferenceFilter Orde

20、r and DistortionWeakly nonlinearS.PavanFundamentals of Continuous-Time ADCs30 2024 IEEE International Solid-State Circuits ConferenceFilter Order and DistortionWeakly nonlinearS.PavanFundamentals of Continuous-Time ADCs30 2024 IEEE International Solid-State Circuits ConferenceFilter Order and Distor

21、tionWeakly nonlinearS.PavanFundamentals of Continuous-Time ADCs30 2024 IEEE International Solid-State Circuits ConferenceFilter Order and DistortionWeakly nonlinearIntermodulationdistortionS.PavanFundamentals of Continuous-Time ADCs30 2024 IEEE International Solid-State Circuits ConferenceFilter Ord

22、er and DistortionWeakly nonlinearIM3S.PavanFundamentals of Continuous-Time ADCs31 2024 IEEE International Solid-State Circuits ConferenceFilter Order and DistortionS.PavanFundamentals of Continuous-Time ADCs32 2024 IEEE International Solid-State Circuits ConferenceFilter Order and DistortionEvery bi

23、quad processeslarge input distortion addsS.PavanFundamentals of Continuous-Time ADCs33 2024 IEEE International Solid-State Circuits ConferenceFilter Order and DistortionFirst biquad processeslarge input Others see small inputsS.PavanFundamentals of Continuous-Time ADCs34 2024 IEEE International Soli

24、d-State Circuits ConferenceFilter Order and DistortionFirst biquad processeslarge input Others see small inputsS.PavanFundamentals of Continuous-Time ADCs34Key TakeawayMore biquads More distortion 2024 IEEE International Solid-State Circuits ConferenceSimple-Minded CT-ADC:ProblemsAnti-alias filter a

25、dds noise and distortion+power dissipationFilter gain=1Noise of filter,buffer,ADC all add equallySharper filter More power,more noise and more distortionGain=1S.PavanFundamentals of Continuous-Time ADCs35 2024 IEEE International Solid-State Circuits ConferenceSimple-Minded CT-ADC:ProblemsAnti-alias

26、filter adds noise and distortion+power dissipationFilter gain=1Noise of filter,buffer,ADC all add equallySharper filter More power,more noise and more distortionGain=1Is there a better way to realize the same functionality?S.PavanFundamentals of Continuous-Time ADCs35 2024 IEEE International Solid-S

27、tate Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-time residueS.PavanFundamentals of Continuous-Time ADCs36 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-t

28、ime residueInputS.PavanFundamentals of Continuous-Time ADCs36 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-time residueInputS.PavanFundamentals of Continuous-Time ADCs36Coarse ADC/DAC 2024 IEEE International S

29、olid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-time residueInputApproximation toinput waveformS.PavanFundamentals of Continuous-Time ADCs36Coarse ADC/DAC 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pi

30、peline ADCBasic idea:Digitize the filtered continuous-time residueInputContinuous-time residueApproximation toinput waveformS.PavanFundamentals of Continuous-Time ADCs36Coarse ADC/DAC 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the

31、filtered continuous-time residueInputContinuous-time residueApproximation toinput waveformS.PavanFundamentals of Continuous-Time ADCs36 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-time residueInputContinuous-

32、time residueApproximation toinput waveformS.PavanFundamentals of Continuous-Time ADCs36td=0 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-time residueS.PavanFundamentals of Continuous-Time ADCs37td=0.5TsInputCo

33、ntinuous-time residue 2024 IEEE International Solid-State Circuits ConferenceSolution:Continuous-Time Pipeline ADCBasic idea:Digitize the filtered continuous-time residueTakeawayInput path delay=ADC-DAC path delayto keep residue smallS.PavanFundamentals of Continuous-Time ADCs37td=0.5TsInputContinuo

34、us-time residue 2024 IEEE International Solid-State Circuits ConferenceResidue with a High-Frequency InputS.PavanFundamentals of Continuous-Time ADCs38 2024 IEEE International Solid-State Circuits ConferenceResidue with a High-Frequency InputS.PavanFundamentals of Continuous-Time ADCs39 2024 IEEE In

35、ternational Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs40 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs40Residue amplifying filter 2024 IEEE International Solid

36、-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs40Residue amplifying filter 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs40Residue amplifying filter 2024 IEEE Internation

37、al Solid-State Circuits ConferenceResidue amplifying filterContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs41 2024 IEEE International Solid-State Circuits ConferenceResidue amplifying filterContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs41 2024 IEEE Int

38、ernational Solid-State Circuits ConferenceResidue amplifying filterContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs42 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs43DigitalDigital 2024 IEEE Intern

39、ational Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs43DigitalDigitalDigital 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs43DigitalDigitalDigitalDigital 2024 IEEE

40、 International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs44 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCFiltered inputS.PavanFundamentals of Continuous-Time ADCs44 2024 IEEE International Solid-State C

41、ircuits ConferenceContinuous-Time Pipeline ADCFiltered inputS.PavanFundamentals of Continuous-Time ADCs44Q.noise(backend)2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCFiltered inputDigital outputS.PavanFundamentals of Continuous-Time ADCs44Q.noise(backend)2024 IE

42、EE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs45Filtered inputDigital outputQ.noise(backend)2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs46 2024 I

43、EEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs46 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs46CTP output 2024 IEEE International Solid-State Ci

44、rcuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs47 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs47Input:delayed,filtered,sampledQuant.noise 2024 IEEE International Solid-State Cir

45、cuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs47Input:delayed,filtered,sampledQuant.noiseAnti-alias filter+ADC rolled into one!Pavan et.al.,TCASII 2021 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of C

46、ontinuous-Time ADCs48Input:delayed,filtered,sampledQuant.noiseSTF =H(s)e-stdNTF =1/G 2024 IEEE International Solid-State Circuits ConferenceContinuous-TimePipeline ADCS.PavanFundamentals of Continuous-Time ADCs49 2024 IEEE International Solid-State Circuits ConferenceContinuous-TimePipeline ADCS.Pav

47、anFundamentals of Continuous-Time ADCs49Input 2024 IEEE International Solid-State Circuits ConferenceContinuous-TimePipeline ADCApprox.inputS.PavanFundamentals of Continuous-Time ADCs49Input 2024 IEEE International Solid-State Circuits ConferenceContinuous-TimePipeline ADCFiltered input-Filtered app

48、rox.input+q.noiseApprox.inputS.PavanFundamentals of Continuous-Time ADCs49Input 2024 IEEE International Solid-State Circuits ConferenceContinuous-TimePipeline ADCFiltered input-Filtered approx.input+q.noiseFiltered approx.inputApprox.inputS.PavanFundamentals of Continuous-Time ADCs49Input 2024 IEEE

49、International Solid-State Circuits ConferenceContinuous-TimePipeline ADCFiltered input-Filtered approx.input+q.noiseFiltered approx.inputFiltered input+q.noiseApprox.inputS.PavanFundamentals of Continuous-Time ADCs49Input 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipelin

50、e ADCS.PavanFundamentals of Continuous-Time ADCs50Contributions ofthese paths cancel 2024 IEEE International Solid-State Circuits ConferenceContinuous-Time Pipeline ADCS.PavanFundamentals of Continuous-Time ADCs51STF =H(s)e-stdNTF =1/G 2024 IEEE International Solid-State Circuits ConferenceCT-Pipeli

51、ne:Example implementationS.PavanFundamentals of Continuous-Time ADCs52 2024 IEEE International Solid-State Circuits ConferenceCT-Pipeline:Example implementationDelay lineS.PavanFundamentals of Continuous-Time ADCs52 2024 IEEE International Solid-State Circuits ConferenceCT-Pipeline:Example implement

52、ationCoarse ADC/DACS.PavanFundamentals of Continuous-Time ADCs52 2024 IEEE International Solid-State Circuits ConferenceCT-Pipeline:Example implementationResidue-amplifying filterS.PavanFundamentals of Continuous-Time ADCs52 2024 IEEE International Solid-State Circuits ConferenceCT-Pipeline:Example

53、implementationBack-endADCS.PavanFundamentals of Continuous-Time ADCs52 2024 IEEE International Solid-State Circuits ConferenceResistive inputimpedanceS.PavanFundamentals of Continuous-Time ADCs53CT-Pipeline:Example implementation 2024 IEEE International Solid-State Circuits ConferenceResistive input

54、impedanceAnti-alias filtering+gainS.PavanFundamentals of Continuous-Time ADCs53CT-Pipeline:Example implementation 2024 IEEE International Solid-State Circuits ConferenceResistive inputimpedanceAnti-alias filtering+gainBack-end ADC noise dividedby gainS.PavanFundamentals of Continuous-Time ADCs53CT-P

55、ipeline:Example implementation 2024 IEEE International Solid-State Circuits ConferenceResistive inputimpedanceAnti-alias filtering+gainOpamps need not settle Back-end ADC noise dividedby gainS.PavanFundamentals of Continuous-Time ADCs53CT-Pipeline:Example implementation 2024 IEEE International Solid

56、-State Circuits ConferenceMultistage Continuous-Time Pipeline ADCsGain=4Gain=4S.PavanFundamentals of Continuous-Time ADCs54 2024 IEEE International Solid-State Circuits ConferenceHigh-order anti-alias filteringMultistage Continuous-Time Pipeline ADCsGain=4Gain=4S.PavanFundamentals of Continuous-Time

57、 ADCs54 2024 IEEE International Solid-State Circuits ConferenceNoise and distortion reduced by 16Multistage Continuous-Time Pipeline ADCsGain=4Gain=4S.PavanFundamentals of Continuous-Time ADCs54 2024 IEEE International Solid-State Circuits ConferenceMultistage Continuous-Time Pipeline ADCsGain=4Gain

58、=4Step-size larger by 16S.PavanFundamentals of Continuous-Time ADCs54 2024 IEEE International Solid-State Circuits ConferenceMultistage Continuous-Time Pipeline ADCsS.PavanFundamentals of Continuous-Time ADCs55 2024 IEEE International Solid-State Circuits ConferenceMultistage Continuous-Time Pipelin

59、e ADCsS.PavanFundamentals of Continuous-Time ADCs55STF 2024 IEEE International Solid-State Circuits ConferenceMultistage Continuous-Time Pipeline ADCsS.PavanFundamentals of Continuous-Time ADCs55STFNTF=1/G2 2024 IEEE International Solid-State Circuits ConferenceMultistage CT-Pipeline ADCs:NoiseVirtu

60、ally same noise as order increasesBreaks the fundamental trade off between order and noise!S.PavanFundamentals of Continuous-Time ADCs56 2024 IEEE International Solid-State Circuits ConferenceStand-Alone Filter vs CTP:Power DissipationPower dissipation for a given noise Stand-alone filter:Goes as(or

61、der)2 CTP:Independent of orderAssumes perfect digital reconstructionNeglects digital-reconstruction powerS.PavanFundamentals of Continuous-Time ADCs57 2024 IEEE International Solid-State Circuits ConferenceCTP:Amplifier LinearityS.PavanFundamentals of Continuous-Time ADCs58 2024 IEEE International S

62、olid-State Circuits ConferenceCTP:Amplifier LinearityS.PavanFundamentals of Continuous-Time ADCs58 2024 IEEE International Solid-State Circuits ConferenceCTP:Amplifier LinearityS.PavanFundamentals of Continuous-Time ADCs58 2024 IEEE International Solid-State Circuits ConferenceCTP:Amplifier Linearit

63、yResidue is small and noise likeS.PavanFundamentals of Continuous-Time ADCs58 2024 IEEE International Solid-State Circuits ConferenceCTP:Amplifier LinearityResidue is small and noise likeHarmonic distortion due to amplifiers is smallS.PavanFundamentals of Continuous-Time ADCs58 2024 IEEE Internation

64、al Solid-State Circuits ConferenceCTP:Amplifier LinearityResidue is small and noise likeHarmonic distortion due to amplifiers is smallAssumes linear DAC and perfect reconstructionS.PavanFundamentals of Continuous-Time ADCs58 2024 IEEE International Solid-State Circuits ConferenceStand-Alone Filter v

65、s CTP:LinearityWeakly-nonlinear single-stage OTAsS.PavanFundamentals of Continuous-Time ADCs59 2024 IEEE International Solid-State Circuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Step-size=S.PavanFundamentals of Continuous-Time ADCs60Simple-mindedCT-ADC 2024 IEEE International Solid-State Ci

66、rcuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Simple-mindedCT-ADCGain=16Step-size=Continuous-timePipelineS.PavanFundamentals of Continuous-Time ADCs61Two-stage exampleG=4 in each stage 2024 IEEE International Solid-State Circuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Simple-mindedCT

67、-ADCGain=16Step-size=Continuous-timePipelineStep-size=16S.PavanFundamentals of Continuous-Time ADCs61Two-stage exampleG=4 in each stage 2024 IEEE International Solid-State Circuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Simple-mindedCT-ADCGain=16Step-size=Continuous-timePipelineStep-size=16S

68、maller,lower powerS.PavanFundamentals of Continuous-Time ADCs61Two-stage exampleG=4 in each stage 2024 IEEE International Solid-State Circuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Simple-mindedCT-ADCGain=16Step-size=Continuous-timePipelineStep-size=16Smaller,lower powerBuffereliminatedS.Pa

69、vanFundamentals of Continuous-Time ADCs61Two-stage exampleG=4 in each stage 2024 IEEE International Solid-State Circuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Simple-mindedCT-ADCGain=16Step-size=Continuous-timePipelineStep-size=16Smaller,lower powerBuffereliminatedS.PavanFundamentals of Con

70、tinuous-Time ADCs61Two-stage exampleG=4 in each stageLess noise&Less distortion 2024 IEEE International Solid-State Circuits ConferenceBasic CT-ADC versus CT-PipelineGain=1Simple-mindedCT-ADCGain=16Step-size=Continuous-timePipelineStep-size=16Smaller,lower powerResistive inputBuffereliminatedS.Pavan

71、Fundamentals of Continuous-Time ADCs61Two-stage exampleG=4 in each stageLess noise&Less distortion 2024 IEEE International Solid-State Circuits ConferenceFinding the Reconstruction Filter (A)S.PavanFundamentals of Continuous-Time ADCs62Foreground techniqueImmune to dc offsetsThermal noise+averaging

72、enhance back-end ADC resolutionHardware efficientPavan et.al.,JSSC 2024 2024 IEEE International Solid-State Circuits ConferenceFinding the Reconstruction Filter (A)S.PavanFundamentals of Continuous-Time ADCs62Foreground techniqueImmune to dc offsetsThermal noise+averaging enhance back-end ADC resolu

73、tionHardware efficientPavan et.al.,JSSC 2024 2024 IEEE International Solid-State Circuits ConferenceFinding the Reconstruction Filter (B)S.PavanFundamentals of Continuous-Time ADCs63Shibata et.al.,ISSCC 2020 2024 IEEE International Solid-State Circuits ConferenceFinding the Reconstruction Filter (B)

74、S.PavanFundamentals of Continuous-Time ADCs63Background techniqueShibata et.al.,ISSCC 2020 2024 IEEE International Solid-State Circuits ConferenceFinding the Reconstruction Filter (B)S.PavanFundamentals of Continuous-Time ADCs63Background techniquepn PRBS-1,1 sequenceShibata et.al.,ISSCC 2020 2024 I

75、EEE International Solid-State Circuits ConferenceFinding the Reconstruction Filter (B)S.PavanFundamentals of Continuous-Time ADCs63Background techniquepn PRBS-1,1 sequenceAveragepn-k.vbn=-G.h1kShibata et.al.,ISSCC 2020 2024 IEEE International Solid-State Circuits ConferenceFinding the Reconstruction

76、 Filter (B)S.PavanFundamentals of Continuous-Time ADCs63Background techniquepn PRBS-1,1 sequenceAveragepn-k.vbn=-G.h1kCorrelator bank hardware intensiveShibata et.al.,ISSCC 2020 2024 IEEE International Solid-State Circuits ConferenceCTP:Input at fsS.PavanFundamentals of Continuous-Time ADCs64u(t)=A

77、cos(2fst)2024 IEEE International Solid-State Circuits ConferenceCTP:Input at fsS.PavanFundamentals of Continuous-Time ADCs65u(t)=A cos(2fst)v1n=A 2024 IEEE International Solid-State Circuits ConferenceCTP:Input at fsS.PavanFundamentals of Continuous-Time ADCs66u(t)=A cos(2fst)v1n=Av1(t)=A 2024 IEEE

78、International Solid-State Circuits ConferenceCTP:Input at fsS.PavanFundamentals of Continuous-Time ADCs67u(t)=A cos(2fst)AA.G 2024 IEEE International Solid-State Circuits ConferenceCTP:Input at fsS.PavanFundamentals of Continuous-Time ADCs67u(t)=A cos(2fst)AA.GAmaxG 1 out of band Digital filter|STF|

79、1 in alias band Implicit anti-aliasing 2024 IEEE International Solid-State Circuits ConferenceNTF(1stord)STF(1stord)NTF(2ndord)STF(2ndord)f/fsSTF(dB)40dB/decBS.PavanFundamentals of Continuous-Time ADCs862nd-Order CTDSM 2024 IEEE International Solid-State Circuits ConferenceNTF(1stord)STF(1stord)NTF(

80、2ndord)STF(2ndord)f/fsSTF(dB)40dB/decBS.PavanFundamentals of Continuous-Time ADCs862nd-Order CTDSM-3dB bandwidth of STF2:B fs 2024 IEEE International Solid-State Circuits ConferenceNTF(1stord)STF(1stord)NTF(2ndord)STF(2ndord)f/fsSTF(dB)40dB/decBS.PavanFundamentals of Continuous-Time ADCs862nd-Order

81、CTDSM-3dB bandwidth of STF2:B fsSTF2 second-order roll-off 2024 IEEE International Solid-State Circuits ConferenceNTF(1stord)STF(1stord)NTF(2ndord)STF(2ndord)f/fsSTF(dB)40dB/decBS.PavanFundamentals of Continuous-Time ADCs862nd-Order CTDSM-3dB bandwidth of STF2:B fsSTF2 second-order roll-off|NTF2|NTF

82、1|in signal band 2024 IEEE International Solid-State Circuits ConferenceNTF(1stord)STF(1stord)NTF(2ndord)STF(2ndord)f/fsSTF(dB)40dB/decBS.PavanFundamentals of Continuous-Time ADCs862nd-Order CTDSM-3dB bandwidth of STF2:B fsSTF2 second-order roll-off|NTF2|NTF1|in signal bandSignal bandwidth B,Implici

83、t antialiasing 2024 IEEE International Solid-State Circuits ConferenceCTP to CT-Multistage Noise Shaping ADC(MASH)S.PavanFundamentals of Continuous-Time ADCs87Replace filter and back-end ADCwith a CTDSM 2024 IEEE International Solid-State Circuits ConferenceCTP to CT-Multistage Noise Shaping ADC(MAS

84、H)S.PavanFundamentals of Continuous-Time ADCs87Replace filter and back-end ADCwith a CTDSM 2024 IEEE International Solid-State Circuits ConferenceCTP to CT-MASHS.PavanFundamentals of Continuous-Time ADCs88 2024 IEEE International Solid-State Circuits Conference0-1 CT-MASH ADCS.PavanFundamentals of C

85、ontinuous-Time ADCs890-1 CT-MASH ADC 2024 IEEE International Solid-State Circuits Conference0-X CT-MASH ADC:ReconstructionS.PavanFundamentals of Continuous-Time ADCs90 2024 IEEE International Solid-State Circuits Conference0-X CT-MASH ADC:ReconstructionS.PavanFundamentals of Continuous-Time ADCs90H(

86、s)STF(s)2024 IEEE International Solid-State Circuits Conference0-X CT-MASH ADC:ReconstructionS.PavanFundamentals of Continuous-Time ADCs90H(s)STF(s)Qb QbNTF(z)2024 IEEE International Solid-State Circuits Conference0-X CT-MASH ADC:ReconstructionS.PavanFundamentals of Continuous-Time ADCs91H(s)STF(s)Q

87、b QbNTF(z)Digital filter Remove shaped noise of the back-end ADC 2024 IEEE International Solid-State Circuits Conference1-2 CT-MASHS.PavanFundamentals of Continuous-Time ADCs92Basic Idea:Stage 2 digitizes the quantization error of Stage 1 2024 IEEE International Solid-State Circuits Conference1-2 CT

88、-MASHS.PavanFundamentals of Continuous-Time ADCs92Stage 1Basic Idea:Stage 2 digitizes the quantization error of Stage 1 2024 IEEE International Solid-State Circuits Conference1-2 CT-MASHS.PavanFundamentals of Continuous-Time ADCs92Stage 1Stage 2Basic Idea:Stage 2 digitizes the quantization error of

89、Stage 1 2024 IEEE International Solid-State Circuits Conference1-2 CT-MASHS.PavanFundamentals of Continuous-Time ADCs92Stage 1Stage 21ststage q.noiseBasic Idea:Stage 2 digitizes the quantization error of Stage 1 2024 IEEE International Solid-State Circuits Conference1-2 CT-MASHS.PavanFundamentals of

90、 Continuous-Time ADCs93Stage 11ststage q.noise 2024 IEEE International Solid-State Circuits Conference1-2 CT-MASHS.PavanFundamentals of Continuous-Time ADCs94Reconstruction1ststage q.noiseCan be shown that STF(s)=STF1(s)STF2(s)NTF(z)=NTF1(z)NTF2(z)2024 IEEE International Solid-State Circuits Confere

91、nceSummary and ConclusionsS.PavanFundamentals of Continuous-Time ADCs95 Continuous-time pipeline(CTP)Suitable for low OSR(wide bandwidths)No feedback loop to close More area-and power-efficient than a filter-ADC cascade Digital reconstruction is key Emerging architecture 2024 IEEE International Soli

92、d-State Circuits ConferenceSummary and ConclusionsS.PavanFundamentals of Continuous-Time ADCs96 Continuous-time Delta-Sigma Suitable for high OSR(low bandwidths)Challenge Closing a mixed-signal feedback loop Q.noise shaped out of the signal band STFs 3dB bandwidth Signal bandwidth STFs gain very low

93、 in alias bands Implicit antialiasing 2024 IEEE International Solid-State Circuits ConferenceSummary and ConclusionsS.PavanFundamentals of Continuous-Time ADCs97 Continuous-time MASH Multi-stage Noise Shaping Wider bandwidth than CTDSM High order STF&NTF with low-order loops Digital reconstruction i

94、s a challenge 2024 IEEE International Solid-State Circuits ConferencePapers to see at ISSCC 2024S.PavanFundamentals of Continuous-Time ADCs CT-Pipeline-paper 22.2 CT Delta-Sigma papers 9.5,9.6 2024 IEEE International Solid-State Circuits ConferenceReferencesS.PavanFundamentals of Continuous-Time ADC

95、s99CT-Pipeline(a)Shibata et.al.,ISSCC 2017(b)Shibata et.al.,JSSC Dec 2017(c)OHare et.al.,TVLSI Feb 2018(d)Shibata et.al.,ISSCC 2020(e)Pavan et.al.,TCASII Mar 2021(f)Manivannan et.al.,SSCL April 2021(g)Pavan et.al.,TCASI Feb 2022(h)Basavaraj et.al.,TCASII Oct 2022(i)Manivannan et.al.,TCASI Aug 2022(j

96、)Kumar et.al.,TCASI Oct 2023(k)Pavan et.al.,JSSC Jan 2024(l)Basavaraj et.al.,TCASI 2024(m)Ismail et.al.,TCASI Dec 2022(n)Mittal et.al.,VLSI May 2023 2024 IEEE International Solid-State Circuits ConferenceReferencesS.PavanFundamentals of Continuous-Time ADCs100CT-DS&CT-MASH(a)Understanding DS Data Co

97、nverters(2ndEdition),Pavan,Schreier and Temes(b)Breems,JSSC Dec 2004(c)Lie et.al.,JSSC Dec 2022(d)Liang et.al.,TCASII June 2022(e)Dong et.al.,JSSC Dec 2016 2024 IEEE International Solid-State Circuits ConferenceThank you!S.PavanFundamentals of Continuous-Time ADCs101 2024 IEEE International Solid-State Circuits ConferenceS.PavanFundamentals of Continuous-Time ADCs Please Scan to Rate This Paper