台大LDO讲义2

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1、PrinciplesofSwitchingDC-DCConverterAnalysisControllerDesign•Effectofnegativefeedbackonthenetworktransferfunctions¢Feedbackreducesthetransferfunctionfromdisturbancestotheoutput¢Feedbackcausesthetransferfunctionfromthereferenceinputtotheoutputtobeinsensitive

2、tovariationsinthegainsintheforwardpathoftheloop•Constructionoftheimportantquantities1/(1+T)andT/(1+T)andtheclosed-looptransferfunctions•Stability¢Therelationbetweenphasemarginandclosed-loopdampingfactor¢Transientresponsevs.dampingfactor•Regulatordesign¢Lea

3、d(PD)compensator¢Lag(PI)compensator¢Combined(PID)compensator¢Designexample低功率混合晶片設計實驗室2LAB802Introduction•Outputvoltageofaswitchingconverterdependsondutycycled,inputvoltagev,andgloadcurrentiload低功率混合晶片設計實驗室3LAB802TheDcRegulatorApplication•Objective:maintai

4、nconstantoutputvoltagev(t)=V,inspiteofdisturbancesinv(t)andi(t)gload•Typicalvariationinv(t):100Hzorg120Hzripple,producedbyrectifiercircuit•Loadcurrentvariations:asignificantstep-changeinloadcurrent,suchasfrom50%to100%ofratedvalue,maybeapplied•Atypicaloutpu

5、tvoltageregulationspecification:5V±0.1V•Circuitelementsareconstructedtosomespecifiedtolerance•Inhighvolumemanufacturingofconverters,alloutputvoltagesmustmeetspecifications低功率混合晶片設計實驗室4LAB802TheDcRegulatorApplication(cont’d)•Sowecannotexpecttosetthedutycycl

6、etoasinglevalue,andobtainagivenconstantoutputvoltageunderallconditions•Negativefeedback:buildacircuitthatautomaticallyadjuststhedutycycleasnecessary,toobtainthespecifiedoutputvoltagewithhighaccuracy,regardlessofdisturbancesorcomponenttolerances低功率混合晶片設計實驗室

7、5LAB802NegativeFeedback:ASwitchingRegulatorSystem低功率混合晶片設計實驗室6LAB802NegativeFeedback低功率混合晶片設計實驗室7LAB802EffectofNegativeFeedbackontheNetworkTransferFunctions•Smallsignalmodel:open-loopconverter低功率混合晶片設計實驗室8LAB802VoltageRegulatorSystemSmall-SignalModel•Usesm

8、all-signalconvertermodel•Perturbandlinearizeremainderoffeedbackloop:低功率混合晶片設計實驗室9LAB802RegulatorSystemSmall-SignalBlockDiagramConverterPowerStageT(s)低功率混合晶片設計實驗室10LAB802SolutionofBlockDiagramopen-looptransfer