LOW POWER HIGH EFFICIENCY INTEGRATED CLASS-D AMPLIFIER CIRCUITS FOR MOBILE ...

252 Pages·2015·2.63 MB·English

LOWPOWERHIGHEFFICIENCYINTEGRATEDCLASS-DAMPLIFIER
CIRCUITSFORMOBILEDEVICES
ADissertation
by
ADRIANISRAELCOLLI-MENCHI
SubmittedtotheOfficeofGraduateandProfessionalStudiesof
TexasA&MUniversity
inpartialfulfillmentoftherequirementsforthedegreeof
DOCTOROFPHILOSOPHY
ChairofCommittee, EdgarSánchez-Sinencio
CommitteeMembers, SamuelPalermo
HamidToliyat
ZenónMedina-Cetina
HeadofDepartment, ChananSingh
May 2015
MajorSubject: ElectricalEngineering
Copyright2015 AdrianIsraelColli-Menchi
ABSTRACT
The consumer’s demand for state-of-the-art multimedia devices such as smart phones
andtabletcomputershasforcedmanufacturerstoprovidemoresystemfeaturestocompete
for a larger portion of the market share. The added features increase the power consump-
tion and heat dissipation of integrated circuits, depleting the battery charge faster. There-
fore,low-powerhigh-efficiencycircuits,suchastheclass-Daudioamplifier,areneededto
reduceheatdissipationandextendbatterylifeinmobiledevices. Thisdissertationfocuses
on new design techniques to create high performance class-D audio amplifiers that have
lowpowerconsumptionandoccupylessspace.
The first part of this dissertation introduces the research motivation and fundamentals
of audio amplification. The loudspeaker’s operation and main audio performance met-
rics are examined to explain the limitations in the amplification process. Moreover, the
operating principle and design procedure of the main class-D amplifier architectures are
reviewedtoprovidetheperformancetradeoffsinvolved.
The second part of this dissertation presents two new circuit designs to improve the
audio performance, power consumption, and efficiency of standard class-D audio ampli-
fiers. The first work proposes a feed-forward power-supply noise cancellation technique
forsingle-endedclass-Damplifierarchitecturestoimprovethepower-supplyrejectionra-
tio across the entire audio frequency range. The design methodology, implementation,
and tradeoffs of the proposed technique are clearly delineated to demonstrate its simplic-
ity and effectiveness. The second work introduces a new class-D output stage design
for piezoelectric speakers. The proposed design uses stacked-cascode thick-oxide CMOS
transistorsattheoutputstagethatmakespossibletohandlehighvoltagesinalowvoltage
standard CMOS technology. The design tradeoffs in efficiency, linearity, and electromag-
ii
neticinterferencearediscussed.
Finally, the open problems in audio amplification for mobile devices are discussed
to delineate the possible future work to improve the performance of class-D amplifiers.
For all the presented works, proof-of-concept prototypes are fabricated, and the measured
resultsareusedtoverifythecorrectoperationoftheproposedsolutions.
iii
DEDICATION
ToGodandtomyfamily.
iv
ACKNOWLEDGEMENTS
Firstandforemost,IwouldliketothankGodforalltheblessingsthatHehasbestowed
uponme. WithoutHisgrace,Iwouldhavebeenlost.
"TheLordismyrock,myfortress,andmydeliverer,myGod,myrockinwhomItake
refuge,myshield,andthehornofmysalvation,mystronghold." (Psalm18:2)
I would like to thank my advisor, Dr. Edgar Sánchez-Sinencio, for his invaluable
support and motivation throughout the development of this research. I am grateful for his
academicguidance,professionaladvisement,andfriendship.
Iwouldliketothankmycommitteemembers,Dr. SamuelPalermo,Dr. HamidToliyat,
and Dr. Zenón Medina-Cetina for all their comments and suggestions to improve the
qualityoftheresearchpresentedinthisdissertation.
I would like to express my sincere gratitude to my wife, Liliana, for her unconditional
love, support, encouragement, and patience. Many thanks to my parents, Jose and Ana,
fortheirconstantsupportandmotivation. IamalsogratefultomylittlesisterMonica,for
herloveandcomprehension.
IwouldlikepresentmydeepappreciationtoMiguelRojas-GonzalezandJoselynTor-
res for the numerous technical discussions that helped to develop this research work.
Thanks also to my research colleagues Jorge Zarate, Salvador Carreon, Efrain Gaxiola,
JiayiJin,XiaosenLiu,FernandoLavalle,andCarlosBriseno.
Finally, thanks to the National Council of Science and Technology (CONACYT) of
Mexicofortheeconomicsupportthroughoutmostofmydoctoralstudies.
v
NOMENCLATURE
BTL BridgeTiedLoad
CDA Class-DAmplifier
CMOS ComplementaryMetalOxideSemiconductor
DMOS Double-DiffusedMetalOxideSemiconductor
DEMOS DrainExtendedMetalOxideSemiconductor
EM Electromagnetic
EMI ElectromagneticInterference
GBW GainBandwidthProduct
IMD IntermodulationDistortion
LDMOS LaterallyDiffusedMetalOxideSemiconductor
NMOS NegativeChannelMetalOxideSemiconductor
PCB PrintedCircuitBoard
PFM PulseFrequencyModulation
PMOS PositiveChannelMetalOxideSemiconductor
PSRR PowerSupplyRejectionRatio
PWM PulseWidthModulation
PZ Piezoelectric
RMS RootMeanSquare
SNR SignaltoNoiseRatio
SMC SlidingModeControl
SPL SoundPressureLevel
THD TotalHarmonicDistortion
THN+N TotalHarmonicDistortionplusNoise
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TABLEOFCONTENTS
Page
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
DEDICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
TABLEOFCONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
LISTOFFIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x
LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Researchimpact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Dissertationorganization . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. FUNDAMENTALSANDMETRICSOFAUDIOAMPLIFICATION . . . . . 6
2.1 Principlesofsoundandaudio . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 Soundandaudiodefinition . . . . . . . . . . . . . . . . . . . . . 6
2.1.2 Soundpressurelevel . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Loudspeakertransducersinmobiledevices . . . . . . . . . . . . . . . . . 9
2.2.1 Electromagneticspeaker . . . . . . . . . . . . . . . . . . . . . . 10
2.2.2 Piezoelectricspeaker . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Performancemetricsofaudioamplifiers . . . . . . . . . . . . . . . . . . 14
2.3.1 Totalharmonicdistortionplusnoise . . . . . . . . . . . . . . . . 15
2.3.2 Signaltonoiseratio . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3.3 Powersupplyrejectionratio . . . . . . . . . . . . . . . . . . . . 18
2.3.4 Powersupplyintermodulationdistortion . . . . . . . . . . . . . . 20
2.3.5 Powerefficiency . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.4 Audioamplifierclassification . . . . . . . . . . . . . . . . . . . . . . . . 25
3. PRINCIPLESOFCLASS-DAUDIOAMPLIFIERS . . . . . . . . . . . . . . 30
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Page
3.1 Class-Damplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.1.1 Advantagesanddisadvantagesofclass-Damplifiers . . . . . . . . 33
3.1.2 Class-Damplifierpowerlosses . . . . . . . . . . . . . . . . . . . 34
3.1.3 Typicalapplications . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.1.4 Commercialclass-Daudioamplifierstypicalspecifications . . . . 39
3.2 Closeloopclass-Darchitectures . . . . . . . . . . . . . . . . . . . . . . 40
3.2.1 Pulsewidthmodulation . . . . . . . . . . . . . . . . . . . . . . . 44
3.2.2 Sigma-deltamodulation . . . . . . . . . . . . . . . . . . . . . . . 53
3.2.3 Self-oscillatingmodulation . . . . . . . . . . . . . . . . . . . . . 61
3.2.4 Modulationarchitecturecomparison . . . . . . . . . . . . . . . . 72
3.3 Class-Ddesignimplementationtradeoffs . . . . . . . . . . . . . . . . . . 73
3.3.1 Compensatoramplifier . . . . . . . . . . . . . . . . . . . . . . . 74
3.3.2 Pulse-widthmodulator . . . . . . . . . . . . . . . . . . . . . . . 83
3.3.3 Class-Doutputstage . . . . . . . . . . . . . . . . . . . . . . . . 87
3.3.4 Outputfilter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
3.3.5 Currentandvoltagesensortechniques . . . . . . . . . . . . . . . 99
4. AFEEDFORWARDPOWERSUPPLYNOISECANCELLATION
TECHNIQUEFORCLASS-DAMPLIFIERS . . . . . . . . . . . . . . . . . . 106
4.1 Power-supplynoiseprobleminclass-Daudioamplifiers . . . . . . . . . . 106
4.2 Power-supplynoisemodelinginclass-Daudioamplifiers . . . . . . . . . 109
4.2.1 Single-endedload . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.2.2 Bridge-tiedload . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
4.3 Proposedfeed-forwardpower-supplynoisecancellationtechnique . . . . 113
4.3.1 ProposedFFPSNCtechniquedescription . . . . . . . . . . . . . 115
4.3.2 Class-DwithFFPSNCtechniquecircuitimplementation . . . . . 119
4.4 Proposedtechniquetradeoffsandmethodology . . . . . . . . . . . . . . 127
4.4.1 FFPSNCtechniqueimplementationtradeoffs . . . . . . . . . . . 129
4.4.2 FFPSNCtechniquedesignprocedure . . . . . . . . . . . . . . . . 131
4.5 SimulationresultsofproposedFFPSNCtechnique . . . . . . . . . . . . . 133
4.6 ExperimentalresultsofCDAwithFFPSNCtechnique . . . . . . . . . . . 137
4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
5. AHIGH-EFFICIENCYSELF-OSCILLATINGCLASS-D
AMPLIFIERFORPIEZOELECTRICSPEAKERS . . . . . . . . . . . . . . . 147
5.1 BackgroundinaudioamplifiersforPZspeakers . . . . . . . . . . . . . . 147
5.2 Class-Damplifierdesignconsiderationsforpiezoelectricspeakers . . . . 149
5.3 Proposedclass-Darchitectureforpiezoelectricspeakers . . . . . . . . . . 151
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5.3.1 Architecturedescription . . . . . . . . . . . . . . . . . . . . . . 152
5.3.2 Compensatordesign . . . . . . . . . . . . . . . . . . . . . . . . 153
5.3.3 Self-oscillatingmodulatordesign . . . . . . . . . . . . . . . . . . 154
5.3.4 OutputfilterdesignforPZspeakers . . . . . . . . . . . . . . . . 157
5.4 Proposedstacked-cascodeH-bridgeoutputstage . . . . . . . . . . . . . . 160
5.4.1 Stacked-cascodeoutputstagedescription . . . . . . . . . . . . . 161
5.4.2 Stacked-cascodeoutputstageoperation . . . . . . . . . . . . . . 163
5.4.3 Gatedriverdesign . . . . . . . . . . . . . . . . . . . . . . . . . . 166
5.5 ExperimentalresultsofCDAforPZspeakers . . . . . . . . . . . . . . . 170
5.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
6. OPENPROBLEMSINCLASS-DAMPLIFIERS . . . . . . . . . . . . . . . . 179
6.1 Class-Damplifiercurrenttrends . . . . . . . . . . . . . . . . . . . . . . 179
6.2 AudioCODECintegration . . . . . . . . . . . . . . . . . . . . . . . . . 181
7. SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
APPENDIXA. CLASS-GAMPLIFIERCASESTUDY . . . . . . . . . . . . . . 202
A.1 Class-Gamplificationbackground . . . . . . . . . . . . . . . . . . . . . 202
A.2 Proposedclass-Gimplementation . . . . . . . . . . . . . . . . . . . . . . 204
A.3 Class-Gdesigntradeoffs . . . . . . . . . . . . . . . . . . . . . . . . . . 208
A.4 Experimentalresultsofproposedclass-Gamplifier . . . . . . . . . . . . 215
A.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
APPENDIXB. CLASS-DAMPLIFIERWITHSLIDINGMODE . . . . . . . . . 220
B.1 Designoftheproposedclass-DarchitecturewithISMC . . . . . . . . . . 220
B.2 Integralslidingmodecontroller . . . . . . . . . . . . . . . . . . . . . . . 222
B.3 ExperimentalresultsofCDAwithISMC . . . . . . . . . . . . . . . . . . 227
B.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
APPENDIXC. PAPERCONTRIBUTIONS . . . . . . . . . . . . . . . . . . . . . 234
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LISTOFFIGURES
FIGURE Page
1.1 Proposedsolutiontocancelsupplynoise(Section4). . . . . . . . . . . 3
1.2 Proposedsolutiontodrivepiezoelectricspeakers(Section5). . . . . . . 4
2.1 Audioamplifieroperation. . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Audiowaveformacrossdistance. . . . . . . . . . . . . . . . . . . . . . 7
2.3 EMspeakerphysicalstructuresideview. . . . . . . . . . . . . . . . . . 10
2.4 EMelectricalimpedanceversusfrequency. . . . . . . . . . . . . . . . . 11
2.5 PZspeakerphysicalstructuresideview. . . . . . . . . . . . . . . . . . 12
2.6 PZandEMspeakersimpedanceversusfrequencycomparison. . . . . . 13
2.7 THD+Ntypicalplotagainstoutputpowerforaudioamplifiers. . . . . . 16
2.8 Typicaloutputfrequencyspectrumforaudioamplifiers. . . . . . . . . . 18
2.9 PSRR measurement example for a noise signal at 217 Hz with -20 dB
amplitude. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.10 PS-IMD measurement example for a noise signal at 217 Hz and audio
signalat1kHz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.11 InstantaneousandaveragepowerforaEMspeakerwithϕ <15°. . . . . 22
∼
2.12 InstantaneousandaveragepowerforaPZspeakerwithϕ =90°. . . . . 23
2.13 Complexpowerdefinition. . . . . . . . . . . . . . . . . . . . . . . . . 24
2.14 Mainlinearamplificationclasses. . . . . . . . . . . . . . . . . . . . . . 25
2.15 Class-Gamplifieroperation. . . . . . . . . . . . . . . . . . . . . . . . 26
2.16 Class-Hamplifieroperation. . . . . . . . . . . . . . . . . . . . . . . . 27
2.17 Class-Damplifieroperation,timedomain. . . . . . . . . . . . . . . . . 28
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