Voltage Regulators for Next Generation Microprocessors PDF
Preview Voltage Regulators for Next Generation Microprocessors
Voltage Regulators for Next Generation Microprocessors . Toni Lo´pez Reinhold Elferich Eduard Alarco´n l l Voltage Regulators for Next Generation Microprocessors ToniLo´pez ReinholdElferich PhilipsResearch PhilipsResearch Weisshausstrasse2 Weisshausstrasse2 D-52066Aachen D-52066Aachen Germany Germany [email protected] [email protected] EduardAlarco´n TechnicalUniversityofCatalunya DepartmentofElectronicsEngineering TelecomEngineeringOffice105 c/GranCapita`s/n 08034Barcelona Spain ISBN978-1-4419-7559-1 e-ISBN978-1-4419-7560-7 DOI10.1007/978-1-4419-7560-7 SpringerNewYorkDordrechtHeidelbergLondon # SpringerScienceþBusinessMedia,LLC2011 Allrightsreserved.Thisworkmaynotbetranslatedorcopiedinwholeorinpartwithoutthewritten permissionofthepublisher(SpringerScience+BusinessMedia,LLC,233SpringStreet,NewYork,NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software,orbysimilarordissimilarmethodologynowknownorhereafterdevelopedisforbidden. Theuseinthispublicationoftradenames,trademarks,servicemarks,andsimilarterms,eveniftheyare notidentifiedassuch,isnottobetakenasanexpressionofopinionastowhetherornottheyaresubject toproprietaryrights. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Toourfamilies . Preface With the rapid advances in computer processing speed and consequent increasing demands in energy consumption of CPUs, soon it became obvious that break- throughs may need to be realized to enable compliant power units featuring compact sizeandhighefficiency.Itwas then,aroundyear2000,whenagroupof scientistsledbyProf.Dr.ThomasDu¨rbaumdecidedtostartitallupatthePhilips researchlabsfromAachen,Germany. Inthepowerelectronicscommunity,researcherswerealreadywonderingabout whatcouldbedonetodrivesuchstringentloads.TheCenterofPowerElectronics Systems(CPES)fromtheVirginiaTechinstitute,amongothers,hadalreadystarted exploringnumerousconvertertopologiesasalternativestothemostwidelyadopted hard-switchingscheme:Thebuckconverter. The strategy in Aachen was far more conservative and yet not less ambitious. Thekeyquestiontostartupwithwas:WhatmakestheMOSFETssohot?Atthat time,manyspecialistsbelievedthattheONstateresistanceandtheMillercapaci- tancewerethemajorcausesoflossesintheconverter.AsMOSFETtechnologists effusively exploited the simple and extensively used Q ·R expression as GD DSon baseline for their technology developments, soon it was realized that behind the apparentsimplicityofthebuckconvertertherewerenumerouslyhidden,generally unwantedelementsthatmadefastswitchingoperationafarmorecomplexcombi- nationofdynamiceffectsthaninitiallyexpected.Theaddeddifficultywassuchthat switching phenomena may only be accurately describable with an awfully large nonlinearimpedancenetwork.“That’sfun!!”OrthatisatleastwhatIthoughtback thenwhenIfirstglancedatafirstattempttomodeltheconverterwithmorethan30 lumpedelements:“Parasiticelementscomealwaysforfree,”Thomasusedtosay. “Well...”Iusedtothink,“ifitwasso,MOSFETswouldbealotcheaper.” The complexity of the equivalent network that accurately described switching transientshadtobeimplementedinacircuitsimulator.TheAachenteamhadthus thetasktobuildadedicatedmacroMOSFETmodelforSPICE.Combinedwithan extensive device characterization for the calibration of the model parameters, the numerical calculations should enlighten the foundations of switching phenomena, vii viii Preface which will then lead the team to the right answer to the initially formulated question. This answer would be of great value to Philips Semiconductors (now NXPSemiconductors),astheycouldalreadyexperiencethattheirfigureofmerits started to be highly inaccurate and even misleading. Therefore, collaborations betweenthetwoorganizationsstarted. Shortly after everything was in place and rolling, I joined the Aachen team, formed by Reinhold Elferich, Dr. Tobias Tolle, Thomas, and myself. The team from Philips Semiconductors was led by Dr. Phil Rutter, from Hazel Grove, UK. Colleagues like Steven T. Peake and Nick Koper were crucial to provide us with model data from device physics calculations and other relevant information to investigate the performance benefits of solutions such as power multichip modules, which were emerging at that time as potential alternatives to overcome anumberoflimitationsofexistingdiscretesolutions. Through this intensive communication the so-called virtual design loop con- cept emerged as a methodology for Hazel Grove to receive direct feedback from circuit simulations regarding the performance of their novel virtual MOSFET structures, which they could refine accordingly before their actual technological implementation. Unfortunatelyforus,ThomasjoinedtheUniversityofErlangen(Germany)and later, Tobias moved to Philips Lighting, leaving Reinhold and myself as the only membersoftheAachenteam. The disentanglement of Philips Semiconductors that gave birth to NXP Semi- conductorchangedthecourseofeventsquiteconsiderably.Resultsweretransferred to NXP so that Phil’s team could carry on with their relentless technology devel- opments employing the new methods and modeling tools, whereas I continued a parallelworkincollaborationwithProf.Dr.EduardAlarco´n,fromthePolytechnic UniversityofCatalunya,Barcelona,Spain,whogavemeallthesupportIhaveever neededtoturnthisindustriallyorientedprojectintoanacademicthesis. As the reader will notice, this treatise goes beyond finding the answer to the initialformulatedquestion.Essentialtomeetingthetargetrequirementshasbeenan overview of all critical aspects of the converter by means of active simulations. Thus,Chap.2throughChap.5extensivelyanalyzesanumberofcircuitanddevice models mainly devoted to MOSFET switching analysis. Each modeling approach isthoroughlydescribedinseparatechaptersintermsofimplementation,function- ality,computationrequirements,andperformancepredictions.Thelatterareexten- sivelysupportedwithexperimentaldata. The potential use of every model will be highlighted in each corresponding chapterbymeansofanalyzingparticularaspectsoftheconvertercircuit.Therefore, in Chap. 2, an in-depth analysis of power MOSFETs’ switching behavior and related loss mechanisms will be provided based on a MOSFET model for circuit simulations. In Chap. 3, a piecewise linear model will be developed to study switching phenomena at a fundamental level. Different case examples will be presented to illustrate the need to move towards integrating power solutions. In Chap. 4, a power loss model will be used to breakdown the losses of a multichip module and quantify important loss mechanisms under fast switching operation. Preface ix Chap.5focusesondesignguidelinesforconverteroptimization.Relevantelements of the converter will be considered, including the passive filter elements and the gatedrivers.SpecialemphasiswillbegiventothedesignofthepowerMOSFETs andtheselectionoftheswitchingfrequencyandnumberofphases. Chap.6exploitsthedevelopedmodelstodeterminetheperformancelimitations of the converter topology and proposes measures to enhance its performance. Basedontheguidelines ofChap.5,thepowerdensityandefficiencylimitsofthe converter based on present and future technologies will be identified. Finally, roadmap targets and improvement options for next generation power solutions willbepresentedanddiscussed. ConclusionsandfutureworkwillbeexposedinChap.7. Theappendixsectionsoffertechnicaldetailsthat,forthesakeofcompleteness, allowthereadertodwellonsomeofthecentraldiscussionswithextensiveancillary information. Because this dissertation would not have been possible without them, thanks gotoDr.PhilRutter,Prof.Dr.ThomasDuerbaum,andProf.Dr.EduardAlarco´n. My thanks go as well with great appreciation to Reinhold Elferich, Dr. Tobias Tolle, and Nick Koper for their incommensurable guidance. Special thanks go to Steven T. Peak, Jim Parkin, Steven Hodgskiss, Victor Guijarro, and Mark Gadja fromNXPSemiconductorsfortheirpricelesssupport. Aachen,Germany ToniLo´pez .
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