CMOS Operational and RF Power Amplifiers for Mobile Communications

182 Pages·2005·2.26 MB·English

KATHOLIEKEUNIVERSITEITLEUVEN
FACULTEITTOEGEPASTEWETENSCHAPPEN
DEPARTEMENTELEKTROTECHNIEK
KasteelparkArenberg10,3001Leuven(Heverlee)
CMOS Operational and RF Power
Amplifiers for Mobile Communications
Promotor: Thesissubmittedtoobtainthe
Prof. Dr. ir. M.Steyaert degreeofdoctorinapplied
sciences
by
Joa˜oRamos
March2005

KATHOLIEKEUNIVERSITEITLEUVEN
FACULTEITTOEGEPASTEWETENSCHAPPEN
DEPARTEMENTELEKTROTECHNIEK
KasteelparkArenberg10,3001Leuven(Heverlee)
CMOS Operational and RF Power
Amplifiers for Mobile Communications
Jury: Thesissubmittedtoobtainthe
Prof. Dr. ir. L.Froyen,Chairman degreeofdoctorinapplied
Prof. Dr. ir. M.Steyaert,Promotor sciences
Prof. Dr. ir. W.Sansen
Prof. Dr. ir. B.Nauwelaers by
Prof. Dr. ir. W.Dehaene
Prof. Dr. Eng. Mª. Rosa´rio(IST,Portugal) Joa˜oRamos
Ir. L.Cloetens(STMicroelectronics)
UDC:621.3.049.77
March2005
© KatholiekeUniversiteitLeuven—FaculteitToegepasteWetenschappen
KasteelparkArenberg1,B-3001Leuven(Belgium)
All rights reserved. No part of the publication may be reproduced in any form, by
print,photoprint,microfilmoranyothermeanswithoutpriorwrittenpermissionfrom
theauthororthepromotor.
Forrequestsorinformationaboutthereproductionofpartsofthiswork,contactK.U.Leuven,
Dept. Elektrotechniek,KasteelparkArenberg10,B-3001Heverlee,Belgium.
D/2005/7515/23
ISBN90-5682-588-7
Acknowledgments
On the 17th August 2000 I arrived in Belgium to start what would become a unique
experienceinmylife. InalotofaspectsthisPh.D.wasthebeginningofanewera–
rangingfromtheenrichingexperienceoflivinginthemulti-culturalcitythatLeuven
is, to the possibility of doing research in a renowned international center for analog
circuitdesign. Inparticular,Iwouldliketothank:
• Prof. M. Steyaert, my promotor, for his support during my stay in Leuven, by
providingtheconditionsthatmadethisworkpossibleandalwayshavingamo-
tivatingattitudeevenduringdifficulttimes. I’mparticularthankfulforthefree-
domofresearchthatIhaveenjoyedunderhissupervision,afreedomthatInever
hadbefore,norwilleverhaveagain.
• Prof. W.Sansen,headofMICAS.Hishardworkandexcellentqualitiesinpass-
ingonhisknowledgehavecontributedtopositionthegrouponaninternational
level.
• W.SansenandB.Nauwelaers,membersofthereadingcommitteefortheirsug-
gestions,feedbackandcorrectionsthathelpedimprovethequalityofthetext.
• Prof. W. Dehaene, Prof. Mª. Rosa´rio and Ir. L. Cloetens members of the jury
and Prof. L. Froyen, chairman of the jury, for their valuable time spent on the
evaluationofthisresearchwork.
• MycolleagueswithwhomIhavesharedoffice91.21. KennethFrancken,Xiao-
hongPeng,MarianVerhelstandYvesVanderperren.I’mthankfulforyouhaving
madethatperiodapleasanttime,mostofthetimes! ;-)
• Kenneth Francken and Libin Yao for their help during the defense preparation
andfororganizingallthepaperworkthatallowsmetodefendthisthesis.
• YannZinzius, LibinYao, JurgenDeveugele, PhilippeCoppejans, TimPiessens
andBramDeMuerforallthediscussionsconcerninganalogcircuitdesign,mea-
surementsandmanuscriptpreparation. AspecialthankstoErikLauwersforhis
guidance.
• Those from different technical backgrounds, with whom during this research
work I have shared ideas: Kenneth Francken from ESAT-MICAS, Guilherme
Lujan and Augusto Redolfi from IMEC, Samuel Xavier-de-Souza from ESAT-
SISTA and Manuel Yarleque from ESAT-TELEMIC. Their experience, com-
ments and fruitful discussions have undoubtedly contributed to the success of
thisdoctorate.
i
ii ACKNOWLEDGMENTS
• TheskilledtechnicalteamatMICAS:ElviraWouters, BenGeeraerts, Danielle
Vermetten, Chris Mertens, Chris Van Grieken, Frederik Daenen, Albert Boon,
Noe¨lla Gaethofs, Michel De Cooman, Viviane Muls, Tony Van Nuland, Piet
Vanderwegen. Theirdedicationandcooperationhasallowedmetoconcentrate
onlyondoingresearch.
• TheESATcomputeradministratorteam: FrankSchoeters,PietHendriks,Marc
Mangelschots,StefVerbruggen,RikTheysandEricOlemans,deservecreditfor
ESATalwayshavingarunningcomputerinfrastructure,evenduringweekends.
• AnDeRuyck,LucianaBaracchiniandStijnSpeelmanforbeingastheyare.
• The Brazilian community, Karin Fischer and Nacho Lopezmalo together with
persons from all over the world, has made this experience memorable. Their
company at Alma or Pangaea, in going to the cinema or in their houses is not
forgotten.
• Paulo Bernardino, Paulo Santos and Augusto Marques for their friendship and
forbeingtherewheneverneeded.
• TheFundac¸a˜oparaaCieˆnciaeaTecnologia,Portugal,forthefinancialsupport
thatmadethisresearchworkpossible.
• Mostofall,Ithankyouthathavegivenmeunconditionallovethattomeisthe
definitionoffamily. God, towhomIhaveprayedandtheOnethatwasalways
present.
The technical results are summarized in this book that you are about to read. The
humanexperiencewillalwaysbeinmymindastheresultofthissingularexperience.
Ithankyouall!
Joa˜oRamos
Leuven,March2005
Abstract
In this era where the desire to always be within reach of a communication device is
largerthanever,thereisagrowingneedforthedevelopmentofcircuitsthatmakethe
dreamofthisGlobalVillageareality. Mobility,whileremainingreachableatalltimes,
ispossiblewiththeuseofwirelesscommunicationsthathavethecommoncharacter-
istic of having a limited power source in the battery. This asks for circuit techniques
that increase the portable electronic device autonomy. A higher autonomy makes a
productmoreusable,lighter(becauseasmallerbatteryisnecessary),andassuchmore
appealingtotheconsumer. Systemswithahigherfunctionality,highercapacityanda
slickdesignareonlypossibleifpowerconsumptionisreducedtotheminimum. Fur-
thermore, new products are developed on a regular basis. As a consequence, system
integratorsandeveryoneworkinginsuchacompetitiveenvironmentseetheirtime-to-
market as a small window of opportunity. All design steps until the product reaches
theshopshelveshavetobeoptimized. Usually,thefirststepsintheengineeringdevel-
opmentrequirealargepercentageofthistime,whichhastobeminimizedtokeepthe
priceslow.
The presented work covers the modeling, analysis, design, optimization and IC char-
acterizationoftwodifferenttypesofamplifiersinCMOSsuitabletobeintegratedon
atransceiverformobilecommunications.
The design of a low-power, low-voltage and high efficiency three stage operational
amplifieriscoveredinthefirstpart. Anewfrequencycompensationtopologyispre-
sented and analyzed in detail in terms of some of the most common characteristics.
Furthermore, comparison with other frequency compensation topologies, and the im-
pactofdifferentdesigncharacteristics(compensationandloadcapacitor,optimization
emphasis, etc.) on the amplifier performance is presented. This comparison makes
it possible to see the performance of each compensation topology without the influ-
enceofexternaldesignfactorsbycomparingalltopologiesunderthesameconditions.
Subsequently, the effect of the positioning of the poles and its impact on the power
consumptionisaddressed. Finally, theproposedfrequencycompensationtopologyis
optimizedusingacomputerdesignautomationapproach,simultaneouslyattheblock
andtransistorlevel,resultinginconsiderablepowersavings.
The second part details the design of a power amplifier for the GSM-850 standard.
First,theclassEpoweramplifierdesignmethodologyiscovered. Thesimplifiedstate-
spacemodelandtheautomatedsizingallowtoobtainasimplearchitecturalrepresen-
tationandahighlyaccuratedescriptionoftheRFbehavior. Asaresult,theyareused
togaininsightintothecircuitperformanceswherepreciseequationsincludingcircuit
parasiticsarelacking. Secondly,thepossibilitytoincreasethesupplyvoltagebeyond
iii
iv ABSTRACT
thestatedmaximumsupplyvoltageofstandardCMOSlow-voltagetechnologiesisex-
plored,withtheobjectiveofincreasingtheefficiency.Andfinally,a850-MHz,30dBm
classEpoweramplifierdesignedinstandardCMOStechnologyispresented. Careful
analysisandinclusionofallcircuitandtest-boardparasiticsincombinationwiththeau-
tomatedsizingmethodologyresultinahighefficiencyamplifiersizedinlessthanone
hourofCPUtime. Also,simulationresultsareinverygoodagreementwithmeasure-
ments. Asaconsequenceofthiswork,forasimilaroutputpowerlevelandfrequency
ofoperation,thedesignedPAshowsthehighestefficiencyforacircuitimplementedin
CMOS. Furthermore, this high efficiency is already achieved from low output power
levelswhichisespeciallyimportantasthepoweramplifieristhusnotalwaysworking
atthemaximumpowerlevel.
The two differenttypes of amplifiers described in detail inthe following pages, were
studied,optimized,designed,manufactured,andmeasuredwhilesimultaneouslyaim-
ingatpoweroptimization,reduceddesigncycleandcostsaving.Thetwohigh-performance
amplifiersdesignedincommercial0.35µmCMOStechnologyhavethefollowingsum-
marizedcharacteristics:
• Operational amplifier: with a power consumption of 275 µW and a load of
130 pF//24 kÄ, it achieves a Unity Gain Frequency (UGF) of 2.7 MHz with
aPhaseMargin(PM)of52°. Anaverageslewrateof1.0V/µsismeasured. The
positive and negative settling time to 1 % final settling time error is 1.4 µs and
1.0µs,respectively.
• ClassEpoweramplifier: amaximumPowerAddedEfficiency(PAE)of66%is
measured. Atasupplyvoltageof2.26V,amaximumoutputpowerof955mW
is obtained for an input signal with a frequency equal to 855 MHz. It has a
highefficiencyoverabroadrangeofoutputpowerlevelsandthePAEisalways
greaterthan60%forvaluesabove158mW.
Contents
Acknowledgments i
Abstract iii
Contents v
ListofFigures xi
ListofTables xvii
SymbolsandAbbreviations xix
1 Introduction 1
1.1 MotivationandApplications . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 CostReduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 ResearchWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 OutlineoftheWork . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 PositiveFeedbackFrequencyCompensationforThreeStageAmplifier 7
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 OperationalAmplifiers . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 SingleStageAmplifiers . . . . . . . . . . . . . . . . . . . . 8
2.2.2 TwoStageAmplifiers. . . . . . . . . . . . . . . . . . . . . . 8
2.2.3 ThreeStageAmplifiers . . . . . . . . . . . . . . . . . . . . . 9
2.3 TheNMCStructure . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 ProposedCompensation . . . . . . . . . . . . . . . . . . . . . . . . 14
2.4.1 WorkingPrinciple . . . . . . . . . . . . . . . . . . . . . . . 14
2.4.2 Small-SignalTransferFunction . . . . . . . . . . . . . . . . 15
2.4.3 UnityGainFrequencyandPhaseMargin . . . . . . . . . . . 18
2.4.4 ClosedLoopTransferFunction . . . . . . . . . . . . . . . . 19
v
vi CONTENTS
2.4.5 StabilityAnalysis . . . . . . . . . . . . . . . . . . . . . . . . 20
2.4.6 DesignEquations . . . . . . . . . . . . . . . . . . . . . . . . 20
2.4.7 PowerOptimization . . . . . . . . . . . . . . . . . . . . . . 21
2.5 DesignoftheOperationalAmplifier . . . . . . . . . . . . . . . . . . 22
2.5.1 CircuitImplementationandLayout . . . . . . . . . . . . . . 22
2.5.2 TestSetup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.5.3 MeasuredResults . . . . . . . . . . . . . . . . . . . . . . . . 23
2.5.4 DiscussionoftheResults . . . . . . . . . . . . . . . . . . . . 24
2.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3 TopologyStudyofThreeStageAmplifierFrequencyCompensation 29
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2 ComparisontootherTopologies . . . . . . . . . . . . . . . . . . . . 30
3.2.1 TopologyComparisonandPowerEstimation . . . . . . . . . 30
3.2.2 UnityGainFrequency . . . . . . . . . . . . . . . . . . . . . 31
3.2.2.1 NMC . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.2.2 DFCFC . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.2.3 AFFC . . . . . . . . . . . . . . . . . . . . . . . . 32
3.2.2.4 TCFC . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2.2.5 NMCF . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.2.6 PFC . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2.2.7 SimulationResults . . . . . . . . . . . . . . . . . . 35
3.2.3 SettlingTime . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2.4 FinalComments . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3 Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3.1 BlockLevel: ComparisontotheNMC . . . . . . . . . . . . . 40
3.3.1.1 OptimizationMethod . . . . . . . . . . . . . . . . 41
3.3.1.2 FrequencyResponse . . . . . . . . . . . . . . . . . 41
3.3.1.3 SlewRate . . . . . . . . . . . . . . . . . . . . . . 42
3.3.1.4 SettlingTime . . . . . . . . . . . . . . . . . . . . 42
3.3.2 TransistorLevel . . . . . . . . . . . . . . . . . . . . . . . . 47
3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52