1998 IEEE Optimized Frequency Shaping Circuit Topologies for LDOs

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1、Rincon-MoraandAllen1©1998IEEE.Personaluseofthismaterialispermitted.However,permissiontoreprint/republishthismaterialforadvertisingorpromotionalpurposesorforcreatingnewcollectiveworksforresaleorredistributiontoserversorlists,ortoreuseanycopyrightedcomponentofthisworkinother

2、worksmustbeobtainedfromtheIEEE.Thismaterialispresentedtoensuretimelydisseminationofscholarlyandtechnicalwork.Copyrightandallrightsthereinareretainedbyauthorsorbyothercopyrightholders.Allpersonscopyingthisinformationareexpectedtoadheretothetermsandconstraintsinvokedbyeachau

3、thor’scopyright.Inmostcases,theseworksmaynotberepostedwithouttheexplicitpermissionofthecopyrightholder.OptimizedFrequencyShapingCircuitTopologiesforLDOsGabrielAlfonsoRincon-MoraandPhillipE.AllenSchoolofElectricalandComputerEngineeringGeorgiaInstituteofTechnologyAtlanta,GA3

4、0332-0250AbstractTypicallowdrop-out(LDO)regulatorarchitecturessufferfromaninherentloadregulationperformancelimitation.Thislimitationmanifestsitselfthroughlimiteddcopen-loopgainandresultsfromstringentclosed-loopbandwidthrequirements.Thefrequencyresponseofthesystemishighlyse

5、nsitivetotheloadingconditionstherebymakingpropercompensationalaboriousendeavor.Thispaperdiscussesandaddressesthelimitationonregulatingperformanceimposedbyfrequencycompensation.Rincon-MoraandAllen2SeveralLDOcircuittopologiesaresubsequentlydevelopedtothisend.Theyenhanceloadr

6、egulationperformancebyrelaxingthedcopen-loopgainrestrictions.Thecircuitstructuresessentiallyalterthefrequencyresponseofthesystemviatheerroramplifier.Alowdrop-outregulatoradoptinganembodimentoftheproposedtechniquewasfabricatedintheMOSIS2mmprocesstechnology.Thesystem,designe

7、dforanoutputcapacitorof4.7mF,wasstablewithanequivalentseriesresistance(ESR)rangingfrom0to12W,bypasscapacitorsaddingfrom0to2.2mF,andaload-currentrangingfrom0to50mA.I.IntroductionThemotivationbehindthestudyoflowdrop-out(LDO)regulatorsisdrivenbythegrowingdemandforhigherperfor

8、mancepowersupplycircuits.AnincreasingnumberoflowvoltageapplicationsrequiretheuseofLDOs,i.