NOT Gate: What is it? (Working Principle & Circuit Diagram)

NOT Gate IC SkiptocontentMenuSeptember13,2020February24,2012byElectrical4UContentsWhatisaNOTGate?NOTGateTransistorCircuitDiagramHowaNOTGateWorksNOTGateICWhatisaNOTGate?A NOTgateisalogicgatethatinvertsthedigitalinputsignal.Forthisreason,aNOTgateissometimesisreferredtoasaninverter(nottobeconfusedwitha powerinverter).ANOTgatealwayshashigh(logical1)outputwhenitsinputislow(logical0).Conversely,a logicalNOTgate alwayshaslow(logical0)outputwhentheinputishigh(logical1).ThelogicalsymbolforaNOTgateisshownbelow:IftheinputbinaryvariableofaNOTgateisconsideredasA,thentheoutputbinaryvariableofthegatewillbeĀ.Asthesymbolofnotoperationis(–)bar.IfthevalueofAis1.thenĀ=0andintheoppositeifthevalueofAisthenĀ=1.Truthtableslisttheoutputofaparticulardigitallogiccircuitforallthepossiblecombinationsofitsinputs.ThetruthtableofaNOTgatecanberepresentedas:OtherlogicgatesincludeANDgates,ORgates,NANDgates,NORgates,XORgates,XNORgates.NOTGateTransistorCircuitDiagramANOTgatecaneasilyberealizedbyusingasimplebipolartransistor.ThetransistorcircuitdiagramofaNOTgate(alsoknownasatransistorinverter)isshownbelow:ThetransistordiagramabovewillbeusedtodemonstratehowaNOTEgateworks.HowaNOTGateWorksLetusexaminetheabovetransistorcircuitwhenahighinputvoltageisapplied,i.e.+5V.Inthiscondition,thetransistorTgetsenoughbasepotentialtomakeit‘ON’.AssoonasthetransistorbecomesON,thesupplyvoltage(+5V)atBwillgetapathtotheearththroughtheresistorR.AtONconditionthetransistorwillbehaveshort-circuitedideally,henceentiresupplyvoltagewilldropacrossresistorRandnovoltagewillappearatXandhencetheoutputoftheinverterorNOTgatewillbezero.Inactualfact,therewillbesomevoltagedropacrossthecollectorandemitterevenatONcondition,ofthetransistor.Thiscollector-emittervoltageisabout0.6V.So,attheabove-saidinputcondition,theentiresupplyvoltage+5Vwillnotdropacrosstheresistorinsteaditwillbe5–0.6=4.4V.So,0.6Vispracticallyconsideredaslogicalzeroorlow.Nowletusexaminethecondition,whereinputA=0Vi.e.baseterminalofthetransistorisgivenwith0Vorgrounded.Atthatcondition,asthebaseofthetransistorisat0potential,thetransistorTwillbeinOFFconditionandhence,thesupplyvoltagewillnotgetanypathtotheearthandtheentiresupplyvoltagewillappearattheoutputterminaloftheNOTgatehighorlogical1,wheninputterminalAisloworlogicalzero.NOTGateICTheICavailableatthemarketforNOTgateisIC7404.One7404ICcontainsatotalofsixtransistorsinverterorsimplysixNOTgate.WantToLearnFaster?🎓Getelectricalarticlesdeliveredtoyourinboxeveryweek.Nocreditcardrequired—it’s100%free.AboutElectrical4UElectrical4Uisdedicatedtotheteachingandsharingofallthingsrelatedtoelectricalandelectronicsengineering....RelatedArticlesINHIBITGateTruthTables:WhatAreThey?(Truth…NANDGate:Whatisit?(Working…UniversalGate:NANDandNORGateas…LeaveaCommentCancelreplyCommentNameEmailΔRecentPostsreportthisadPleasefeelfreetocontactusifyou’dliketorequestaspecifictopic.Clickheretoseeourprivacypolicy.WeareaparticipantintheAmazonServicesLLCAssociatesProgram,anaffiliateadvertisingprogramdesignedtoprovideameansforustoearnfeesbylinkingtoAmazon.comandaffiliatedsites.Fulldisclaimerhere.xx