集成电路专业英语 课件 8 Digital Integrated Circuits

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DigitalIntegratedCircuitsIntroduction&Moore'sLawCoreConcept:Thefundamentalbuildingblocksofallmoderncomputingsystems.Builtfrommillionstobillionsofmicroscopictransistorsonasinglesemiconductorchip.TheirdevelopmenthashistoricallyfollowedMoore'sLaw:thenumberoftransistorsonachipdoublesapproximatelyeverytwoyears.Thisexponentialgrowthpowerseverythingfromsmartphonestomedicalequipment.DesignMethodology:Ahierarchicalapproach,startingfrombasiclogicgatesandbuildinguptocomplexdigitalsystems.TheFoundation:BooleanAlgebra&LogicLevelsBooleanAlgebra:Variablesandconstantscanonlyhavetwovalues:0or1.Thesevaluesrepresentlogiclevels,notnumericalvalues.LogicLevelsinPractice:Logic0(LOW):e.g.,0Vto0.8V;Logic1(HIGH):e.g.,2Vto5V.SynonymsforLogic0:False,Off,Low,No,OpenSwitch.SynonymsforLogic1:True,On,High,Yes,ClosedSwitch.BasicOperations:OR,AND,NOT.BasicLogicGates–TheORGateFunction:OutputisHIGH(1)ifanyinputisHIGH(1).BooleanExpression:X=A+B(XequalsAORB).Real-worldAnalogy:AnovenlightturnsoniftheswitchisONORthedoorisopened.BasicLogicGates–TheANDGateFunction:OutputisHIGH(1)onlyifallinputsareHIGH(1).BooleanExpression:X=A·BorX=AB(XequalsAANDB).Real-worldAnalogy:AclothesdryerrunsonlyifthetimerissetANDthedoorisclosed.BasicLogicGates–TheNOTGate(Inverter)Function:Performsinversionorcomplementationonasingleinput.BooleanExpression:X=Ā(XequalsNOTA).KeyProperty:Theoutputisalwaystheoppositeoftheinput.CombinationalCircuits:AnOverviewDefinition:Aninterconnectionoflogicgateswheretheoutputdependsonlyonthecurrentinputvalues.BlockDiagram:nInputVariables→CombinationalLogicCircuit→mOutputVariables.SpecificationMethods:TruthtablesandBooleanfunctions.Examples:Adders,Multiplexers,Decoders,Encoders.CombinationalBuildingBlock:TheHalfAdderPurpose:Addstwosingle-bitbinarynumbers(xandy).Outputs:S(Sum)andC(Carry).BooleanFunctions:S=x'y+xy'(x⊕y),C=xy.CombinationalBuildingBlock:TheFullAdderPurpose:Addsthreesingle-bitbinarynumbers(x,y,andcarry-inz).S=1whenanoddnumberofinputsare1.C=1whentwoorthreeinputsare1.Implementation:TwohalfaddersandoneORgate.CombinationalBuildingBlock:TheMultiplexer(MUX)Function:Adataselectorthatroutesoneofmanyinputlinestoasingleoutputline.Selectionisdeterminedbynselectionlines.Commontypesinclude2-to-1and4-to-1multiplexers.CombinationalBuildingBlock:TheDecoderFunction:Convertsann-bitbinaryinputcodeintoamaximumof2^nactiveoutputlines.OnlyoneoutputisHIGHforanyinputcombination.Usedinmemoryaddressdecodingandbinaryconversion.CombinationalBuildingBlock:TheEncoderFunction:Theinverseofadecoder.Convertsanactiveinputlineintoann-bitbinarycode.Priorityencodersresolvemultipleactiveinputconflicts.SequentialCircuits:AnOverviewOutputsdependoncurrentinputsandpaststate.Storageelementssuchasflip-flopsholdthecircuitstate.Thecircuittransitionsthroughstatesusingaclocksignal.SequentialBuildingBlock:Flip-FlopsSynchronousbistabledevicesthatchangestateataclockedge.Edge-triggered:sensitiveonlytorisingorfallingclockedges.InaDflip-flop,QtakesthevalueofDattheclockedge.SequentialBuildingBlock:LatchesLevel-sensitivebistablestoragedevices.Changestatewhiletheenablesignalisactive.S-Rlatchusescross-coupledNANDgatesandhasaninvalidstate.SequentialBuildingBlock:RegistersAregisterisagroupofnflip-flopsstoringann-bitword.Allflip-flopsshareacommonclock.Shiftregistersmovedataleftorrightfordataconversion.SequentialBuildingBlock:CountersAcountercyclesthroughapredefinedsequenceofstates.Themodulusdefinesthenumberofstatesinthecycle.Ann-bitbinarycountercountsfrom0to2^n−1.CounterTypes:Ripplevs.SynchronousRipplecountersaresimplebutslowduetocumulativepropagationdelay.Synchronouscountersuseacommonclockforallflip-flops.Synchronousdesignsarefasterbutrequiremorelogic.Summary&KeyTakeawaysDigitalICsare