System-level Techniques for Analog Performance Enhancement

232 Pages·2016·16.39 MB·English

by  Bang-Sup Song (auth.)

Bang-Sup Song
System-level
Techniques
for Analog
Performance
Enhancement
System-level Techniques for Analog Performance
Enhancement

Bang-Sup Song
System-level Techniques
for Analog Performance
Enhancement
Bang-SupSong
DepartmentofElectricalandComputerEngineering
UniversityofCalifornia
SanDiego,CA,USA
ISBN978-3-319-27919-0 ISBN978-3-319-27921-3 (eBook)
DOI10.1007/978-3-319-27921-3
LibraryofCongressControlNumber:2015959480
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Preface
Electronics has undergone drastic changes and shifted towards massive digital
signal processing in recent decades. However, even large digital-heavy systems
are built around small analog cores, and analog signal processing is still the
mainstay of the circuit design. Analog circuits have evolved from old discrete
sampled-data circuits to new sophisticated digital-like time-domain switching
circuits.Inthisevolution,numericaldesignmethodsrelyingonnumericalanalysis
havebeenfavored,andsimulationtoolsweregivenunduecreditsforthat.
Analogcircuitsandtheirfundamentalshavebeenimprovedoverthelastcentury
even without computer tools. Old analog designs were to improve circuits in
relativetermsusingmatchingproperties.Onthecontrary,newanalogdesignsare
to obtain absolute parameters such as low figure-of-merit, low power, and high
speed. After 30 years of refinement, analog designers now come to believe that
virtuallyallanalogfunctionsfromDCtoRFcanbeintegratedatlowvoltageseven
with low power. Such euphoria of superior analog performance has been mostly
fueled by aggressive device scaling down to the nanometer scale. It is true that
simulation-baseddesignscanhandlecircuitsoflargecomplexity,butinaneffortto
implementanalogfunctionsonlywithhigh-speeddigitalswitching,thefundamen-
talsofelectronicshavebeenoftenignored.
Moreoftenthannot,simulation-baseddesignsendupwithsomewhatambiguous
anderroneousresultsrangingfromviolatingthefundamentalenergyconservation
lawtoobtaininginstantaneoussmall-signalgainduringbrieflarge-signaltransient
period.Theyhaveveeredoffcoursewithnoobviousends,whichrequirenecessary
corrections. This book raises a concern about such analog design practices and
commonlyoverlookedfallacies. Whilemostrecentliteratures focus onanswering
mostlywhatandhow,thisbookelaboratesmoreonwhyandhow.
Since analog design methodologies are reviewed with specific emphasis on
concepts, college-level engineering knowledge would suffice to understand this
book. It is written in plain descriptive and illustrative terms with no extensive
derivations of equations and simulations so that readers may grasp the essence of
thisbookintuitivelywithoutresortingtonumericalmeans.Therearesevenchapters
v
vi Preface
with examples from DC to RF. After fundamental issues are identified, analog
performance-enhancingmethodsarepresentedrepeatedlyusingthesameprinciple
applicable to the system-level DC servo feedback as well as the simple local
feedback.
This book is mainly written and organized to give proper perspectives on the
analogdesignsatalllevels.Theanalogdesignfieldisbuiltoncollectiveachieve-
ments by numerous contributors, and apologies are extended to those whom the
authorfailedtorefertoorrecognizecorrectlyinthisbook.
LaJolla,CA Bang-SupSong
November2015
Contents
1 Discrete-TimeSwitchingCircuits. . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Comparators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Right,Wrong,orNoDecision. . . . . . . . . . . . . . . . . . . . . 2
1.1.2 Non-GaussianComparatorError. . . . . . . . . . . . . . . . . . . 3
1.1.3 DigitalCorrectionandFeedback. . . . . . . . . . . . . . . . . . . 6
1.1.4 LatchGain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1.5 PreamplifierBandwidth. . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2 DynamicAmplifierandLatch. . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2.1 KickbackinDynamicLatch. . . . . . . . . . . . . . . . . . . . . . . 15
1.2.2 LatchHysteresisandMetastability. . . . . . . . . . . . . . . . . . 17
1.2.3 TransientNoiseinSwitchingCircuits. . . . . . . . . . . . . . . . 18
1.3 AnalogIntegrateandDump. . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4 QuantizationErrorvs.WhiteNoise. . . . . . . . . . . . . . . . . . . . . . . 23
1.5 NoiseImplicationsofSampling. . . . . . . . . . . . . . . . . . . . . . . . . 24
1.6 JitterandTransientDistortion. . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.7 DCWandering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.8 SwitchingforLowPower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2 Continuous-TimeAnalogCircuits. . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.1 NegativeandPositiveFeedbacks. . . . . . . . . . .. . . . . . . . . . . .. . 35
2.1.1 PhaseMargin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.1.2 StabilityofNegativeFeedback. . . . . . . . . . . . . . . . . . . . . 40
2.1.3 InstabilityofPositiveFeedback. . . . . . . . . . . . . . . . . . . . 44
2.2 LocalSeriesandShuntFeedbacks. . . . . . . . . . . . . . . . . . . . . . . . 45
2.2.1 SeriesFeedback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.2.2 SourceFollower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.2.3 InductorSourceDegeneration. . . . . . . . . . . . . . . . . . . . . 49
2.2.4 ResistanceReflectioninSeriesFeedback. . . . . . . . . . . . . 51
2.2.5 ShuntFeedback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
vii
viii Contents
2.3 Trans-ResistanceAmplifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.4 G BoostingandNoiseCancellation. . . . . . . . . . . . . . . . . . . . . . 65
m
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3 AlmostDCCircuits. . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. 69
3.1 RegulatorDCPerformance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.2 RegulatorTransientPerformance. . . . . . . . . . . . . . . . . . . . . . . . 71
3.3 LosslessEnergyTransfer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.4 Switched-CapacitorDC–DCConverters. . . . . . . . . . . . . . . . . . . 75
3.5 Switched-InductorDC–DCConverters. . . . . . . . . . . . . . . . . . . . 78
3.6 GlitchinDC–DCConverters. . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.7 AlmostDCCircuitsforBodySensors. . . . . . . . . . . . . . . . . . . . . 85
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
4 Data-ConverterCircuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4.1 DataAcquisitionandDistribution. . . . . . . . . . . . . . . . . . . . . . . . 93
4.2 Nyquist-Ratevs.OversamplingADC. . . . . . . . . . . . . . . . . . . . . 96
4.2.1 Opamp-BasedADC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
4.2.2 Opamp-FreeADC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.2.3 DigitalCorrectionandFeedback
ofQuantizationError. . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4.2.4 NoiseImplicationsinData-ConverterCircuits. . . . . . . . . 100
4.2.5 Nyquist-RateSARvs.OversamplingCTDSM. . . . . . . . . 102
4.3 IncrementalDSMwithDCInput. . . . . . . . . . . . . . . . . . . . . . . . . 104
4.3.1 IDSMwithInputS/H.. . . . . . . . .. . . . . . . .. . . . . . . .. . 105
4.3.2 CascadedIntegratorsforDCEstimation. . . . . . . . . . . . . . 108
4.3.3 Switched-CapacitorChargeInjector
forInputS/H. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.3.4 InitialTransientError. . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.4 LMS-BasedAdaptiveErrorFeedback. . . . . . . . . . . . . . . . . . . . . 112
4.4.1 LoopfilterforStability. . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.4.2 Self-Calibrationvs.Self-Trimming. . . . . . . . . . . . . . . . . . 114
4.4.3 ErrorMeasurementbyPNDithering. . . . . . . . . . . . . . . . 115
4.5 LMS-BasedAdaptiveServoFeedbackExamples. . . . . . . . . . . . . 116
4.5.1 CapacitorSelf-Trimming. . . . . . . . . . . . . . . . . . . . . . . . . 117
4.5.2 Self-TrimmingDACs. . . . . . . . . . . . . . . . . . . . . . . . . . . 119
4.5.3 Self-TrimmingTimeConstants. . . . . . . . . . . . . . . . . . . . 124
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
5 Switched-CapacitorCircuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
5.1 AnalogSampled-DataProcessing. . . . . . . . . . . . . . . . . . . . . . . . 131
5.2 Opamp-InducedGainError. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
5.3 AccurateInterstageResidueTransfer. . . . . . . . . . . . . . . . . . . . . 136
5.4 HistoryofOpamp-InducedGainErrorCancellation. . . . . . . . . . . 138
5.5 Nonlinearity-CancelledBottom-PlateSampling. . . . . . . . . . . . . . 139
5.6 LMSAdaptationforGainandNonlinearityError. . . . . . . . . . . . . 142
Contents ix
5.6.1 Summing-NodeErrorAmplifier
withProgrammableGain. . . . . . . . . . . . . . . . . . . . . . . . . 144
5.6.2 GainMismatchPolarityDetection
byDigitalDithering. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 146
5.6.3 Self-TrimmingSequence. . . . . . . . . . . . . . . . . . . . . . . . . 147
5.6.4 AccuracyConsiderations. . . . . . . . . . . . . . . . . . . . . . . . . 150
5.7 NoiseImplicationofNonlinearityCancellation. . . . . . . . . . . . . . 152
5.8 EffectofHigh-FrequencyZeroonSettling. . . . . . . . . . . . . . . . . 154
5.9 ExperimentalResults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
6 RFCircuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
6.1 Mixer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
6.2 SensitivityandBlocker. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
6.3 GlobalAGCFeedback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
6.4 ImpedanceMatching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
6.5 DigitalRF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
6.6 SwitchingPowerAmplifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
6.7 Fractional-NFrequencySynthesizer. . . . . . . . . . . . . . . . . . . . . . 182
6.7.1 FractionalSpur. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
6.7.2 DAC-BasedSpurCancellation. . . . . . . . . . . . . . . . . . . . . 186
6.7.3 LMS-BasedDACGainCalibration. . . . . . . . . . . . . . . . . 188
6.7.4 ExperimentalResults. . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
7 Direct-ConversionReceivers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
7.1 DirectorDualConversion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
7.2 FrequencyTranslation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
7.2.1 HarmonicMixingandImageFolding. . . . . . . . . . . . . . . . 198
7.2.2 HarmonicRejection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
7.2.3 ImageRejection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
7.3 ImageinDirect-ConversionReceivers. . . . . . . . . . . . . . . . . . . . . 205
7.3.1 ComplexImage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
7.3.2 ComplexImageRejectionAlgorithm. . . . . . . . . . . . . . . . 207
7.3.3 PathGainandPhaseErrorDetector. . . . . . . . . . . . . . . . . 210
7.3.4 Sign–SignLMSAlgorithmforImageRejection. . . . . . . . 211
7.3.5 Magnitudevs.SignDetection. . . . . . . . . . . . . . . . . . . . . 213
7.3.6 ComplexImageRejection. . . . . . . . . . . . . . . . . . . . . . . . 214
7.3.7 ThreeVariationsofImageRejecter. . . . . . . . . . . . . . . . . 216
7.4 ExperimentalResults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225