linearization of rf power amplifiers with memoryless baseband predistortion method a thesis ...

144 Pages·2011·5.34 MB·English

LINEARIZATIONOFRFPOWERAMPLIFIERSWITHMEMORYLESSBASEBAND
PREDISTORTIONMETHOD
ATHESISSUBMITTEDTO
THEGRADUATESCHOOLOFNATURALANDAPPLIEDSCIENCES
OF
MIDDLEEASTTECHNICALUNIVERSITY
BY
TURUSANKOLCUOG˘LU
INPARTIALFULFILLMENTOFTHEREQUIREMENTS
FOR
THEDEGREEOFMASTEROFSCIENCE
IN
ELECTRICALANDELECTRONICSENGINEERING
MAY2011
Approvalofthethesis:
LINEARIZATIONOFRFPOWERAMPLIFIERSWITHMEMORYLESSBASEBAND
PREDISTORTIONMETHOD
submittedbyTURUSANKOLCUOG˘LUinpartialfulfillmentoftherequirementsforthede-
greeofMasterofScience inElectricalandElectronicsEngineering Department,Middle
EastTechnicalUniversityby,
Prof. Dr. CananO¨zgen
Dean,GraduateSchoolofNaturalandAppliedSciences
Prof. Dr. ˙IsmetErkmen
HeadofDepartment,ElectricalandElectronicsEngineering
Assoc. Prof. Dr. S¸ims¸ekDemir
Supervisor,ElectricalandElectronicsEngineeringDept.,METU
ExaminingCommitteeMembers:
Prof. Dr. CananToker
ElectricalandElectronicsEngineeringDept.,METU
Assoc. Prof. Dr. S¸ims¸ekDemir
ElectricalandElectronicsEngineeringDept.,METU
Prof. Dr. NevzatYıldırım
ElectricalandElectronicsEngineeringDept.,METU
Assist. Prof. Dr. TayfunNesimog˘lu
ElectricalandElectronicsEngineeringDept.,METU
Dr. ArslanHakanCos¸kun
LeadDesignEngineer,ASELSAN
Date:
Iherebydeclarethatallinformationinthisdocumenthasbeenobtainedandpresented
in accordance with academic rules and ethical conduct. I also declare that, as required
bytheserulesandconduct,Ihavefullycitedandreferencedallmaterialandresultsthat
arenotoriginaltothiswork.
Name,LastName: TURUSANKOLCUOG˘LU
Signature :
iii
ABSTRACT
LINEARIZATIONOFRFPOWERAMPLIFIERSWITHMEMORYLESSBASEBAND
PREDISTORTIONMETHOD
Kolcuog˘lu,Turusan
M.Sc.,DepartmentofElectricalandElectronicsEngineering
Supervisor : Assoc. Prof. Dr. S¸ims¸ekDemir
May2011,127pages
In modern wireless communication systems, advanced modulation techniques are used to
supportmoreusersbyhandlinghighdataratesandtoincreasetheutilizationefficiencyofthe
limited RF spectrum. These techniques are sensitive to the nonlinear distortions due to their
highpeaktoaveragepowerratios. Mainsourceofnonlineardistortionintransmittertopolo-
giesarepoweramplifiersthatdeterminetheoverallefficiencyandlinearityofthetransmitter.
To increase linearity without sacrificing efficiency, power amplifier linearization techniques
maybeachoice. Basebandpredistortiontechniqueisknowntobeoneoftheoptimummeth-
ods due to its relatively low complexity and its convenience for adaptation. In this thesis,
differentmemorylessbasebandsignalpredistortionmethodsareinvestigatedandanalyzedby
simulations. Look-Up Table(LUT) and Polynomial approaches are compared and LUT ap-
proachisfoundtobebetterinperformance. Parameters,likeindexing,trainingsequencesand
trainingdurationareevaluated. Anopenlooptestbenchisbuiltwitharealamplifierandadif-
ferentLUTpredistortionmethodthatisbasedonamplifiermodelingisoffered. Itisevaluated
by using two tone test and adjacent channel power suppression with 8PSK data. Also, some
Look-Up Table parameters are re-investigated with the proposed method. The performances
iv
oftheproposedmethodindifferentamplifierclassesareobserved. Alongwiththesestudies,
alistofprerequisitesfordesignofapredistortionsystemisdetermined.
Keywords: Predistortion,Linearization,PowerAmplifier,Look-UpTable
v
¨
OZ
RFGU¨C¸ YU¨KSELTEC¸LER˙INHAFIZASIZTEMELBANTO¨NBOZUNUMYO¨NTEM˙I
˙ILEDOG˘RUSALLAS¸TIRILMASI
Kolcuog˘lu,Turusan
Yu¨ksekLisans,ElektrikveElektronikMu¨hendislig˘iBo¨lu¨mu¨
TezYo¨neticisi : Doc¸. Dr. S¸ims¸ekDemir
Haziran2011,127sayfa
Modernkablosuziletis¸imsistemlerinde,sınırlıRFspektrumukullanımınınverimlilig˘iniartır-
mak ve daha hızlı verileri destekleyerek kullanıcı sayısını artırmak ic¸in gelis¸mis¸ kiplenim
tekniklerikullanılmaktadır. Buteknikler,yu¨ksektepe-ortalamagu¨c¸oranlarındandolayıdog˘ru-
salolmayanbozunumlarakars¸ıhassastırlar. Go¨ndericiyapılarındakidog˘rusalolmayanbozu-
numlarıntemelkaynag˘ı,go¨ndericinintoplamverimlilikvedog˘rusallıg˘ınıbelirleyengu¨c¸ yu¨k-
seltec¸lerdir. Verimlilikteno¨du¨nvermedendog˘rusallıg˘ıartırmakic¸in,gu¨c¸ yu¨kseltec¸leridog˘ru-
sallas¸tırmateknikleribirsec¸enekolabilmektedir. Temelbanto¨nbozunumyo¨ntemi,karmas¸ıklık
ve adaptasyona uygunluk ac¸ısından en optimum metodlardan biri olarak bilinmektedir. Bu
tezde, hafızaetkisiolmayanfarklıtemelbantis¸areto¨nbozunummetotlarıaras¸tırılmıs¸ veben-
zetimlerleincelenmis¸tir. Bas¸vuruc¸izelgelivepolinomsalyaklas¸ımlarkıyaslanmıs¸vebas¸vuru
c¸izelgeliyaklas¸ımındahaiyiperformansasahipoldug˘ugo¨zlemlenmis¸tir. Indeksleme,alıs¸tırma
dizileri ve alıs¸tırma su¨releri gibi parametreler deg˘erlendirilmis¸tir. Gerc¸ek yu¨kseltec¸ ic¸eren
ac¸ık do¨ngu¨ test du¨zeneg˘i kurulmus¸ ve yu¨kseltec¸ modellemesine dayalı farklı bir bas¸vuru
c¸izelgelio¨nbozunummetoduo¨nerilmis¸tir. Buyaklas¸ımikitontestive8PSKdataileyapılan
yankanalgu¨cu¨bastırmamiktarlarıiledeg˘erlendirilmis¸tir. Ayrıca,bazıbas¸vuruc¸izelgeparame-
vi
treleri burada da incelenmis¸tir. Yaklas¸ımın farklı yu¨kseltec¸ sınıflarındaki performansı da
go¨zlemlenmis¸tir. Bu c¸alıs¸maların yanısıra, bir o¨nbozunum sisteminin tasarımı ic¸in gerekli
olano¨nkos¸ullarbelirlenmis¸tir.
AnahtarKelimeler: O¨nbozunum,Dog˘rusallas¸tırma,Gu¨c¸ Yu¨kseltec¸,Bas¸vuruC¸izelgesi
vii
tothememoryofmyfather
viii
ACKNOWLEDGMENTS
IwouldliketoexpressmydeepestgratitudetomysupervisorAssoc. Prof. Dr. S¸ims¸ekDemir
for his guidance, advice, encouragement, and support throughout my thesis work. I have
benefitedfromhisdeepknowledgeanddisciplineonresearch.
I am grateful to my design leader Dr. Arslan Hakan Cos¸kun for his invaluable support
throughoutmythesis.
Iwouldalsoliketoconveythankstojurymembersfortheirvaluablecommentsonthisthesis.
IwishtothanktoMr.Ertug˘rulKolag˘asıog˘lu,Mr.Yalc¸ınAydınandMr.RecepAliYıldırımfor
theirpreciousguidanceandadvicesinmythesisstudy.
IamthankfultomycompanyASELSANInc. forlettingandsupportingofmythesisstudy.
IwouldalsoliketoexpressmyappreciationtoTUBITAKfortheirfinancialsupportthrough-
outthiswork.
Iwouldliketoextendmyspecialappreciationandgratitudetomymotherandsisterfortheir
loveandsupport. Ifeeltheirsupportalwayswithmethroughoutmylife.
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TABLE OF CONTENTS
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
O¨Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
ACKNOWLEDGMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
TABLEOFCONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x
LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
LISTOFFIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
CHAPTERS
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 POWERAMPLIFIERNONLINEARITIESandLINEARIZATION . . . . . 5
2.1 CausesforNonlinearity . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Nonlinearities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 ConsequencesofNonlinearity . . . . . . . . . . . . . . . . . . . . . 14
2.4 NonlinearityCharacterizationParameters . . . . . . . . . . . . . . . 18
2.5 MeasuresofNonlinearity . . . . . . . . . . . . . . . . . . . . . . . 20
2.6 NonlinearModeling . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.7 Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.7.1 PowerEfficiency . . . . . . . . . . . . . . . . . . . . . . 28
2.7.2 CostEfficiency . . . . . . . . . . . . . . . . . . . . . . . 31
2.8 LinearAmplification . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.8.1 CrestFactorReduction . . . . . . . . . . . . . . . . . . . 32
2.8.2 Linearization . . . . . . . . . . . . . . . . . . . . . . . . 33
x