nonlinear characterization and modeling of radio-frequency devices and power amplifiers with ...

210 Pages·2016·10.4 MB·English

ALMA MATER STUDIORUM · UNIVERSITA` DI BOLOGNA
SCUOLA DI INGEGNERIA E ARCHITETTURA
DEI –DipartimentodiIngegneriadell’EnergiaElettricaedell’Informazione
Inco-tutelaconUniversityofLeuven(KULeuven),Lovanio,Belgio
DottoratodiRicercainIngegneriaElettronica,Informaticaedelle
Telecomunicazioni–CicloXVII
SettoreConcorsualediAfferenza: 09/E3–ELETTRONICA
SettoreScientificoDisciplinare: ING-INF/01–ELETTRONICA
NONLINEAR CHARACTERIZATION
AND MODELING OF RADIO-FREQUENCY
DEVICES AND POWER AMPLIFIERS
WITH MEMORY EFFECTS
Presentatada:
GIANPIEROGIBIINO
CoordinatoreDottorato: Relatori:
Prof. A.VANELLI-CORALLI Prof. F.FILICORI
Prof. D.SCHREURS
EsameFinaleAnno2016

ALMA MATER STUDIORUM · UNIVERSITA` DI BOLOGNA
SCUOLA DI INGEGNERIA E ARCHITETTURA
DEI –DipartimentodiIngegneriadell’EnergiaElettricaedell’Informazione
Inco-tutelaconUniversityofLeuven(KULeuven),Lovanio,Belgio
DottoratodiRicercainIngegneriaElettronica,Informaticaedelle
Telecomunicazioni–CicloXVII
SettoreConcorsualediAfferenza: 09/E3–ELETTRONICA
SettoreScientificoDisciplinare: ING-INF/01–ELETTRONICA
NONLINEAR CHARACTERIZATION
AND MODELING OF RADIO-FREQUENCY
DEVICES AND POWER AMPLIFIERS
WITH MEMORY EFFECTS
Presentatada:
GIANPIEROGIBIINO
CoordinatoreDottorato: Relatori:
Prof. A.VANELLI-CORALLI Prof. F.FILICORI
Prof. D.SCHREURS
EsameFinaleAnno2016
©2015AlmaMaterStudiorumAD1088,UniversityofBologna–SchoolofEngineering
Autopubblicato,GianPieroGibiino,VialeRisorgimento2,40136Bologna(Italy)
©2015KULeuven–FacultyofEngineeringScience
Uitgegevenineigenbeheer,GianPieroGibiino,KasteelparkArenberg10box2444,B-3001Heverlee(Belgium)
Allrightsreserved. Nopartofthepublicationmaybereproducedinanyformbyprint,photoprint,microfilm,
electronicoranyothermeanswithoutwrittenpermissionfromthepublisher.
Tuttiidirittiriservati. Nessunapartedellapubblicazionepuòessereriprodottainqualsiasiformapermezzo
stampa,stampafotografica,microfilm,elettronicaoqualsiasialtromezzosenzailpermessoscrittodell’editore.
Allerechtenvoorbehouden. Nietsuitdezeuitgavemagwordenvermenigvuldigden/ofopenbaargemaaktworden
door middel van druk, fotokopie, microfilm, elektronisch of op welke andere wijze ook zonder voorafgaande
schriftelijketoestemmingvandeuitgever.
Preface
This manuscript reports the research results obtained under a collaboration
between the University of Bologna and KU Leuven, which was formalized
in November 2012 through a mutual agreement for the co-tutorship of the
Ph.D. thesis. The work has been developed within the Electronic Design and
Measurement for RF and Industrial Applications (EDM) research group of the
Department of Electrical Engineering (DEI) of the University of Bologna, and
the TELEcommunications and MICrowaves (TELEMIC) research group of the
Department of Electrical Engineering (ESAT) of KU Leuven.
After three years and a half, I can finally acknowledge the people who helped
me out reaching these results. My first thoughts are for my supervisors, Prof.
Filicori and Prof. Schreurs, as they managed to build a common ground for
cooperation. It has been an honor to experience their scientific insights and
to have their encouragement through this journey. Moreover, I would like to
thank them for their flexibility in the organization of the exchange periods,
and for being extremely proactive to financially funding the activity. With
respect to this, I also acknowledge CIRI-MAM (Interdepartmental Center for
Industrial Research of the University of Bologna - Advanced Applications
in Mechanical Engineering and Materials Technology) and FWO (Research
Foundation Flanders).
I wish to express my special thanks to Prof. Santarelli - formally an assessor,
butpracticallyaco-supervisor-notonlyforhisconstantscientificguidanceand
criticaladvice,butalsoforhandlingmostofthebureaucraticandorganizational
matters, the last of which has been acting as chairman in the final defense. I
wouldalsoliketoexpressgratitudetoallmembersoftheexaminationcommittee,
including Prof. Gaquière, Prof. Nauwelaers, and Dr. Avolio, for their valuable
comments and feedbacks.
Being part of two research groups at a time involved many opportunities and
just as many difficulties. The best aspect was undoubtedly the chance to meet
i
ii PREFACE
many talented people, whom I owe much of my professional growth. Therefore,
I wish to mention Daniel, Rafael, Tommaso, Corrado, Rudi and Pier Andrea
from University of Bologna, and Gustavo, Pawel, Mamad, Marco, Saeed, Song,
Alessandra, Raul, Tomislav, and Tom from KU Leuven. Thank you for endless
(yet, never worthless) discussions, and for sharing both sad and happy moments
with me.
I would also like to thank all students met during this period, from the ones
attending the laboratory sessions, to the ones I had the pleasure to supervise
during their thesis project. While I hopefully taught them some basics, they
indirectly helped me out by suggesting innovative perspectives and original
thinking.
Suchanopenresearchnetworkallowedmetocollaboratewithotherinstitutions
and companies. In this sense, I would like to thank Dr. Vanden Bossche and
Dr. Pailloncy from National Instruments, and Dr. Nielsen and Dr. Tafuri
from Keysight Technologies, for sharing hints, providing samples, and lending
hardware.
Last but not least, I am very grateful to my family and friends. Two people
deserve a special mention. My father, for having instilled into me the culture of
hard working to set the bar always a bit higher, and my girlfriend, Aleksandra,
for withstanding and mitigating the human consequences resulting from this.
Gian Piero Gibiino
Bologna, April 2016
Abstract
The fast development of telecommunications systems experienced during the
last two decades has strongly influenced the way we communicate and exchange
information. Yet, much progress is still expected in the coming years with the
introduction of new infrastructures capable of delivering fast data-rates and
ubiquitousconnectivity. Suchadevelopment,however,canonlyhappenthrough
theevolutionofRFtechnologyandsystems,whichshouldbecapableofworking
at high-power, at high-frequency and over a large operating bandwidth. At the
same time, the power dissipation, already a burden for the telecommunication
networkinfrastructure,shouldbeminimized. Inordertoreachthesedemanding
specifications,radio-frequency(RF)poweramplifier(PA)designisevolvingfrom
the classic linear or quasi-linear topology into complex architectures. In such
conditions, variousmechanismsofdistortionarise, whicharedependentbothon
the PA topology as well as on the semiconductor technology upon which the PA
is designed. These should be suitably compensated for, otherwise the system
will not meet the emission constraints and the information it transmits will be
corrupted. Thisworkmakesuseoftailoredlarge-signalmeasurementtechniques
in order to characterize and model such distortions in modern applications. In
particular, two distinct fields of application are investigated. The first one deals
with the characterization and modeling of the non-idealities shown by Gallium
Nitride (GaN) HEMTs, a promising semiconductor technology yet suffering
fromprocessdefects. Inparticular, theeffectofchargetrappingischaracterized
withtheexploitationofadouble-pulsetechnique,capableofpreconditioningthe
charge trapping state and allowing improved understanding of the dispersive
effects. Such an investigation has culminated with the introduction of new
lag-functions for the description of the nonlinear dynamics triggered by traps,
as well as the presentation of a new approach for GaN HEMT modeling. The
second part deals with RF PAs in which the supply voltage is modulated to
obtain higher efficiency, in architectures such as envelope-tracking (ET). In this
work, innovative measurement techniques aimed at the characterization of the
interfacebetweenthePAandthesupplymodulatoratthedrain-supplyterminal,
iii
iv ABSTRACT
has been introduced. Moreover, a three-port behavioral model, taking into
account the presence of a modulated supply voltage and the mutual dynamic
interactionwiththemodulatedRFinput,isproposed. Suchamodel,basedona
modified Volterra series truncation, is also extended to predict the dynamically
drained current and the dynamic power added efficiency (PAE). Finally, a real-
time predistortion algorithm for supply modulated PAs, based on the proposed
modeling approach, is presented.
Sommario
Il rapido sviluppo dei sistemi di telecomunicazione avvenuto durante gli ultimi
vent’anni ha fortemente influenzato il modo in cui comunichiamo e scambiamo
informazioni. Ciò nonostante, nuovi sviluppi sono attesi per i prossimi anni,
con l’introduzione di nuove infrastrutture capaci di fornire connessione a banda
larga e connettività diffusa. Questo sviluppo, d’altra parte, sarà possibile
solo attraverso l’evoluzione della tecnologia e dei sistemi a radiofrequenza, che
dovranno essere in grado di lavorare ad alte potenze, alte frequenze, e a larga
banda. Al tempo stesso, la dissipazione di potenza, già un grosso onere per le
infrastrutture di rete, dovrà essere minimizzata. Per poter raggiungere queste
complesse specifiche, il progetto di amplificatori di potenza a radiofrequenza
sta evolvendo da topologie lineari o quasi lineari a complesse architetture. In
queste condizioni nascono vari meccanismi di distorsione che sono dipendenti
sia dalla topologia dell’amplificatore, che dalla tecnologia dei dispositivi a
semiconduttore utilizzati. Queste distorsioni devono essere adeguatamente
compensate, altrimenti il sistema non potrà garantire le specifiche di emissione,
e l’informazione trasmessa sarà corrotta. Questo lavoro utilizza tecniche di
misura a grande segnale per caratterizzare e modellare queste distorsioni in
casi operativi. In particolare, due campi di interesse vengono qui indirizzati.
Il primo è relativo alla caratterizzazione e la modellazione delle non idealità
mostratedaidispostivielettroniciditipoHEMTinNitrurodiGallio(GaN),una
promettente tecnologia elettronica che però presenta ancora difetti provenienti
da un processo non ancora del tutto maturo. Gli effetti di intrappolamento
di carica vengono qui caratterizzati attraverso l’uso di una tecnica a doppio
impulso, in grado di condizionare lo stato delle trappole e permettere una
comprensione degli effetti dispersivi ad esse correlati. La ricerca in questo
ambito ha prodotto l’introduzione di nuove funzioni dette lag functions, atte
alladescrizionedeglieffettinonlinearidinamiciinnescatidall’intrappolamentodi
carica. A partire da questa caratterizzazione, viene derivato un nuovo modello
compatto per transistori HEMT in Nitruro di Gallio. La seconda parte della
ricercaèinvecedestinataagliamplificatoridipotenzaincuil’alimentazioneviene
v
vi SOMMARIO
modulata per ottenere maggiore efficienza, cosi come avviene in architetture di
tipo envelope-tracking. In questo ambito, vengono introdotte nuove tecniche
di misura, mirate alla caratterizzazione dell’interfaccia tra l’amplificatore di
potenza e il modulatore dell’alimentazione al terminale di drain. In aggiunta,
vienepresentatounmodellocomportamentaleingradodiconsiderarelapresenza
di un’alimentazione dinamica, e la mutua interdipendenza dinamica con un
segnale a radiofrequenza. Questo modello, basato su un troncamento della
serie di Volterra modificata, viene esteso per la predizione della corrente di
drain e l’efficienza dinamica. Infine, per mezzo del modello proposto, viene
presentato un algoritmo per la predistorsione in tempo reale di amplificatori ad
alimentazione dinamica.