Linear Operation of Switch-Mode Outphasing Power Amplifiers

310 Pages·2016·16.04 MB·English

Linear Operation of Switch-Mode
Outphasing Power Amplifiers
Keith Finnerty
A thesis submitted in partial fulfilment of the requirements for
Doctor of Philosophy
Department of Electronic Engineering
National University of Ireland, Maynooth
Ireland
Head of the Department: Ronan Farrell
Supervisors of the Research: Ronan Farrell and John Dooley

Deceleration
Iherebycertifythatthisthesis,whichInowsubmitforassessmentontheprogrammeofstudy
leading to the award of PhD has not been submitted, in whole or part, to this or any other
Universityforanydegreeandis,exceptwhereotherwisestatedtheoriginalworkoftheauthor.
Signature:
January27,2016
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Abstract
Radio transceivers are playing an increasingly important role in modern society. The
”connected” lifestyle has been enabled by modern wireless communications. The demand
that has been placed on current wireless and cellular infrastructure requires increased spectral
efficiency however this has come at the cost of power efficiency. This work investigates
methods of improving wireless transceiver efficiency by enabling more efficient power
amplifier architectures, specifically examining the role of switch-mode power amplifiers in
macro cell scenarios. Our research focuses on the mechanisms within outphasing power
amplifiers which prevent linear amplification. From the analysis it was clear that high power
non-lineareffectsarecorrectablewithcurrentlyavailabletechniqueshowevernon-lineareffects
aroundthezerocrossingpointarenot. Asaresultsignalprocessingtechniquesforsuppressing
andavoidingnon-linearoperationinlowpowerregionsareexplored. Anovelmethodofdigital
pre-distortion is presented, and conventional techniques for linearisation are adapted for the
particular needs of the outphasing power amplifier. More unconventional signal processing
techniques are presented to aid linearisation of the outphasing power amplifier, both zero
crossing and bandwidth expansion reduction methods are designed to avoid operation in non-
linear regions of the amplifiers. In combination with digital pre-distortion the techniques
will improve linearisation efforts on outphasing systems with dynamic range and bandwidth
constraintsrespectively.
Our collaboration with NXP provided access to a digital outphasing power amplifier,
enabling empirical analysis of non-linear behaviour and comparative analysis of behavioural
modelling and linearisation efforts. The collaboration resulted in a bench mark for linear
wideband operation of a digital outphasing power amplifier. The complimentary linearisation
techniques,bandwidthexpansionreductionandzerocrossingreductionhavebeenevaluatedin
bothsimulatedandpracticaloutphasingtestbenches. Initialresultsarepromisingandindicate
thatthebenefitstheyprovidearenotlimitedtotheoutphasingamplifierarchitecturealone.
Overall this thesis presents innovative analysis of the distortion mechanisms of the
outphasingpoweramplifier,highlightingthesensitivityofthesystemtoenvironmentaleffects.
Practicalandnovellinearisationtechniquesarepresented,withafocusonenablingwideband
operationformoderncommunicationsstandards.
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Acknowledgements
IwouldliketotakethistimetothankDr. RonanFarrellforprovidingmewithopportunityto
conductresearchchallengingandinterestingfield. IwouldalsoliketothankDr. RonanFarrell
andDr. JohnDooleyforguidanceandadviceoverthepastcoupleofyears.
NoneofthisworkwouldofoccurredwithoutthefundingprovidedbyTelecommunications
GraduateInitiative,theHigherEducationAuthorityandScienceFoundationIreland,forwhich
Iamextremelygrateful.
I would like to thank colleagues and friends at NXP Netherlands for their contributions
and guidance during our collaboration. I would also like to thank all my colleagues who I
have collaborated with and thank everyone else whom I have interacted with in Maynooth
University during both undergraduate and postgraduate studies. I consider myself very lucky
tohaveencounteredgoodmentors,colleaguesandmostimportantlygreatfriends.
FinallyIwishtothankmyparentsandbrothersfortheirconstantsupport,encouragement
andpatiencethattheyhaveprovidedformyentirelife.
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List of Publications
• K. Finnerty, J. Dooley, and R. Farrell, “Analytical investigation of thermal effects on
outphasingpoweramplifiers,”inIrishSignalandSystemsConference2015,June2015
• K. Finnerty, R. Wesson, J. Dooley, M. Acar, M. van der Heijden, and R. Farrell, “Lin-
earization of an outphasing amplifier for wide-band multi-carrier signals,” Microwave
andWirelessComponentsLetters,IEEE,vol.25,pp.139–141,Feb2015
• K. Finnerty, J. Dooley, and R. Farrell, “Utilizing sparse-aware volterra for power
amplifier behavioral modeling,” in 17th Research Colloquium on Communications and
RadioScienceintothe21stCentury,Dublin,Ireland,March2014
• K.Finnerty,J.Dooley,andR.Farrell,“Patentapplication:Asignalprocessingstagefor
anamplifier,ukapplicationno:1422097.4,”December2014
• K. Finnerty, J. Dooley, , M. Wesson, R. Acar, M. van der Heijden, and R. Farrell,
“Behavioural modeling of outphasing amplification systems,” accepted for publicaion,
MicrowaveTheoryandTechniques,IEEETransactionson,2015
• K. Finnerty, J. Dooley, and R. Farrell, “Fpga serdes capability as switch mode pa mod-
ulator,”inIrishSignalsSystemsConference2014and2014China-IrelandInternational
ConferenceonInformationandCommunicationsTechnologies(ISSC2014/CIICT2014).
25thIET,pp.118–122,June2014
• K.Finnerty,J.Dooley,andR.Farrell,“Digitalquadraturemixingoflowpasssigma-delta
modulatorsforswitch-modepoweramplifiers,”inCircuitTheoryandDesign(ECCTD),
201120thEuropeanConferenceon,pp.282–285,Aug2011
• J. Dooley, B. O’Brien, K. Finnerty, and R. Farrell, “Estimation of sparse memory taps
forrfpoweramplifierbehavioralmodels,”MicrowaveandWirelessComponentsLetters,
IEEE,vol.25,pp.64–66,Jan2015
• K. Finnerty, J. Dooley, and R. Farrell, “Cartesian pre-distortion using a sigma delta
modulator for multi-standard rf power amplifiers,” in Signals and Systems Conference
(ISSC2012),IETIrish,pp.1–5,June2012
• Z.Wang,K.Finnerty,J.Dooley,andR.Farrell,“Alow-rateidentificationschemeofhigh
poweramplifiers,”in17thResearchColloquiumonCommunicationsandRadioScience
v
intothe21stCentury,Dublin,Ireland,March2014
• J. Dooley, K. Finnerty, and R. Farrell, “Comparison of models for multiple nonlinear
poweramplifiersinactiveantennaarrays,”Proceedingsofthe43rdEuropeanMicrowave
Conference,2013
• S.Farsi,J.Dooley,K.Finnerty,D.Schreurs,B.Nauwelaers,andR.Farrell,“Behavioral
modeling approach for array of amplifiers in active antenna array system,” in Power
AmplifiersforWirelessandRadioApplications(PAWR),2013IEEETopicalConference
on,pp.73–75,Jan2013
• S. Farsi, J. Dooley, K. Finnerty, D. Schreurs, B. Nauwelaers, and R. Farrell, “Cross-
memorypolynomialmodelingforrfcircuits,”inMicrowaveIntegratedCircuitsConfer-
ence(EuMIC),20127thEuropean,pp.262–265,Oct2012
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List of Acronyms
2G Secondgenerationmobilecommunicationsstandard
3G Thridgenerationmobilecommunicationsstandard
ACEPR AdjacentChannelErrorPowerRatio
ACP AdjacentChannelPower
ACPR AdjacentChannelPowerRatio
ADC AnaloguetoDigitalConverter
ADS AdvancedDesignSystems
AM AmplitudeModulation
AMPS AdvancedMobilePhoneService
ANN ArtificialNeuralNetworks
CDMA CodeDivisionMultipleAccess
CFR CrestFactorReduction
CORDIC COordinateRotationDIgitalComputer
CSCD CurrentSwitchingClassD
DAC DigitaltoAnalogueConverter
DC DirectCurrent
DPD DigitalPreDistortion
DSP DigitalSignalProcessor
DUT DeviceUnderTest
EER EnvelopeEliminationRestoration
ET EnvelopeTracking
EVM ErrorVectorMagnitude
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FFT FastFourierTransform
FIR FiniteImpulseResponse
FPGA FieldProgrammableGateArrays
FSK FrequencyShiftKeying
GaN GalliumNitride
GMSK GaussianMeanShiftKeying
HEMT High-Electron-MobilityTransistor
HSDPA HighSpeedDownlinkPacketAccess
ICT InformationandCommunicationsTechnology
IIR infiniteImpulseResponse
IM InterModulation
IQ InphaseQuadraturephase
LINC LIneroperationusingNon-linearComponents
LMS LeastMeanSquares
LNA LowNoiseAmplifier
LO LocalOscillator
LS LeastSquares
LTI LinearTimeInvariant
LUT LookUpTable
MLP Multi-LayerPerceptron
MMSE MinimumMeanSquaredError
MOSFET MetalOxideSemiconductorField-EffectTransistor
MSE MeanSquaredError
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NMSE NormalisedMeanSquaredError
NMT NordicMobileTelephone
OFDM OrthogonalFrequencyDivisionMultiplexing
OSR OverSampleRatio
PA PowerAmplifier
PAE PowerAddedEfficiency
PAPR PeaktoAveragePowerRatio
PDM PulseDensityModulation
PLL PhaseLockLoop
PM PhaseModulation
PMPR PeaktoMinimumPowerRatio
PWM PulseWidthModulation
QAM QuadratureAmplitudeModulation
QPSK QuadraturePhaseShiftKeying
RAM RandomAccessMemory
RBNN RadialBiasNeuralNetworks
RF RadioFrequency
RLS RecursiveLeastSquares
RVTDNN RealValuedTimeDelayNeuralNetworks
SCS SignalComponentSeparator
SOM SelfOrganisingMaps
TACS TotalAccessCommunicationsSystem
TDNN TimeDelayNeuralNetworks
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