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ID:40209918
大小:2.27 MB
页数:41页
时间:2019-07-26
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1、DigitalFundamentalsTenthEditionFloydChapter11SummaryProgrammableLogicSPLD:(SimplePLDs)aretheearliesttypeofarraylogicusedforfixedfunctionsandsmallercircuitswithalimitednumberofgates.(ThePALandGALarebothSPLDs).CPLD:(ComplexPLDs)aremultipleSPLDsarraysandinter-connectionarraysonasinglech
2、ip.FPLD:(FieldProgrammableGateArray)areamoreflexiblearrangementthanCPLDs,withmuchlargercapacity.ProgrammableLogicDevices(PLDs)areICswithalargenumberofgatesandflipflopsthatcanbeconfiguredwithbasicsoftwaretoperformaspecificlogicfunctionorperformthelogicforacomplexcircuit.MajortypesofPL
3、Dsare:SummaryProgrammableLogicAdvantagestoPLDsincludeReducedcomplexityofcircuitboardsLowerpowerrequirementsLessboardspaceSimplertestingproceduresHigherreliabilityDesignflexibilitySummaryPALsandGALsPALshaveaonetimeprogrammable(OTP)array,inwhichfusesarepermanentlyblown,creatingtheprodu
4、cttermsinanANDarray.AllPLDscontainarrays.TwoimportantSPLDsarePALs(ProgrammableArrayLogic)andGALs(GenericArrayLogic).AtypicalarrayconsistsofamatrixofconductorsconnectedinrowsandcolumnstoANDgates.SimplifiedAND-ORarrayXAABBSummaryXAABBWhatfunctionisrepresentedbythearray?ExampleSolutionT
5、hefunctionrepresentsanXORgate.X=AB+ABPALsareprogrammedwithaspecializedprogrammerthatblowsselectedinternalfuselinks.Afterblowingthefuses,thearrayrepresentstheBooleanlogicexpressionforthedesiredcircuit.PALsandGALsSummaryTheGAL(GenericArrayLogic)issimilartoaPALbutcanbereprogrammed.Forth
6、isreason,theyareusefulfornewproductdevelopment(prototyping)andfortrainingpurposes.AABBXGALsweredevelopedbyLatticeSemiconductor.Theyarehighspeed,extremelyfastdevicesandcaninterfacewithboth3.3Vor5Vlogicsignals.PALsandGALsSummaryPALsandGALscanberepresentedwithasimplifieddiagram.Asinglel
7、inecanrepresentmultiplegateinputs.ThelogicshownisfortheXORgate,givenpreviously.InputbufferAABBSinglelinewithslashindicatingmultipleANDgateinputsFuseblownFuseintactABABAB+ABPALsandGALsSummaryPALsandGALshavelargearraylogicandincludeoutputlogicthatvariesincomplexity.Theoutputlogicisconn
8、ectedtoeachO
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