NAND Gate : Truth Table, Circuit, Design, Applications and ...

To design a NAND gate using transistor, mostly two bipolar junction transistors are needed. Here, this logic gate is constructed using two NPN ... Youarehere:Home/DigitalElectronics/WhatisNANDGate:Working&ItsApplicationsWeallknowthatlogicgateistheidealizedcomputationalapproachfortheimplementationofaBooleanfunctionwhichiseitherperformedonasingleormorenumberofinputsthusgeneratingsingleoutput.Asperthiscontext,thetermcanbereferredtoasanideallogicgateornon-idealphysicaldevice.Theselogicgatesarebasicallydesignedusingtransistors,relaylogics,diodes,andmanyothermechanicalelements.TheveryfundamentaltypeoflogicgatesisAND,OR,andNOTgates.Alongwiththese,wehaveNANDgateandNORgateswhicharetermedUniversalLogicGates.CharlesPeircedemonstratedthateitherNORorNANDlogicgatesareenoughtoreproducetheoperationofotherlogicgates,buthisdemonstrationwasleftunpublishedtill1933.Then,theinitialproofofpublicationhappenedin1913byHenryM.ShefferandthefunctionalityofNANDistermedasShefferstroke.Andtoday,thisarticlefocusesonexplainingNANDgatedefinition,circuit,truthtable,itsapplications,andadvantages.WhatisNANDGate?NANDgatealsocalledNegatedAND,NOTANDisthecombinationofANDandNOTgateswhichareinseriesconnection.TheNANDgateisoneoftheuniversallogicgatesbecausewiththeuniversalgatesanyotherfundamentaloperationscanbeaccomplished. Therefore,thecombinationofNANDandNORgatescangiveAND,OR,andNOTgates.ThisgategivestheoutputHIGHwhenboththeinputsareatlogicLOWorwheneitheroftheinputsisatalogicLOWstate.ItcanalsobedefinedasthattheoutputisLOWonlywhenboththeinputsareHIGH.TheNANDgateBooleanexpressionisgivenby:A=(X.Y)’Here,XandYaretheinputsandAistheoutput.NANDlogicgatecanbeachievedbymultiplyingalltheinputsandthencomplementingthemultipliedresult.TheNANDgatesymbolisshownasfollows:BasicNOTANDGateNANDGateTypesTherearebasicallythreetypesofNANDlogicgatesdependingonthenumberofinputs.Thoseareexplainedbelow:2-inputNANDHere,thegateacceptstwoinputsandgivessingleoutputwhichisthebasicformationofNANDgate.Here,thetotalpossiblecombinationsofinputsare4.The2-inputNANDgatetruthtableisshownbelow:XYA0010111011103-inputNANDHere,thegateacceptsthreeinputsandgivessingleoutput.Here,thetotalpossiblecombinationsofinputsare8.Thisthree-inputlogicgatecanbeformedbycombininganynumberofindividualinputsThe3-inputNANDlogicgatetruthtableandlogicaldesignisshownbelow:ABCX000100110101011110011011110111103InputNANDMulti-InputNANDSimilartomulti-inputORandANDgates,ann-inputNANDlogicgatecanalsobeformed.Whenthenumberofinputsisodd,theunusedinputsignaliskepthighbyconnectingthisunusedsignaltothepowersupplythroughpull-upresistors.MultiInputNOTANDBelowisthelogicalexpressionandNANDgatedesignfor4-inputNAND.WXYZA00001000110010100111010010101101101011111000110011101011011111001110111110111110TransistorImplementationofNANDTodesignaNANDgateusingtransistor,mostlytwobipolarjunctiontransistorsareneeded.Here,thislogicgateisconstructedusingtwoNPNtransistors,10kOhmsresistors–2,2-4kOhmresistor1,pushbuttons–2,wirestoestablishconnectionsbetweenthecomponents,LEDdisplay,andpowersupply.BelowistheNANDgatecircuitdiagramthatexplainsthefunctionality.NANDGateUsingTransistorAspertheabovediagram,thetwoNPNtransistorsTxandTyareinseriesconnectionandthecircuitconnectionisthesameasANDgate.ThecollectorendofTxhasaconnectionwiththepowersupplyusinga2kOhmresistoranditisalsoconnectedtotheoutput.WhereastheemitterendofTxisconnectedtothecollectorendofTysothatboththetransistorsareinseriesconnection.ThentheemitterendofTyisconnectedtothegroundandthiscompletesthecircuitconnection.Ontheotherhand,thebaseendsofbothTxandTyareconnectedtoinputsXandYthrough10kohmresistorscorrespondingly.ToknowtheexactfunctionalityoftheNegatedAndlogicgateusingatransistor,weneedtoanalyzeallfourcombinationsofinputs.PleaserefertothislinktoknowmoreaboutNANDGateMCQsCase1:WhenX=0andY=0WhenboththeinputsareLOW,thenthetwotransistorsTxandTyoperatingastheswitchdonotpermitforconnectionbetweenemitterandcollectorends.Becauseofthis,whenthereisapowersupplyacrossthecircuit,thecurrentwillnotpasstotheemitterendofTxanditpassesonlytothecollectorendofTx.AsthecollectorendisevenconnectedwithLED,thispowersupplydirectlyreachestoLEDandtheLEDglowsmakingtheoutputasHIGH.Case2:WhenX=0andY=1WhentheYinputisatlogicHIGH,thebaseendofTyestablishesaconnectionbetweenitsemitterandcollectorends.Whereas,theinputatthecollectorendforTyis0whichmeansthereexistsnoconnectioninbetweentheemitterandcollectorendsofTx.Becauseofthis,thepowersupplythatpassestothecollectorendreachestooutputmakingtheLEDdisplayONi.e.outputisHIGH.Case3:WhenX=1andY=0WhentheXinputisatlogicHIGHandYinputisatlogicLOW,theswitchforTxmovestoONandTybecomesOFF.ThismakestheoutputaslogicHIGHwhichissimilartocase2.Case4:WhenX=1andY=1Here,theinputsXandYareatlogicHIGHthismeansthepowersupplydirectlyreachestocollectorendthrough2kOhmresistor.AsboththeinputsareataHIGHstate,thisestablishesadirectconnectionbetweenthecollectorendofTxandtheemitterendofTy.WhereasTyisconnectedtotheground,thepotentialvariationinbetweenthecollectorendofTxandemitterendofTybecomes‘0’.Asthecollectoralsohasaconnectionwithoutput,theLEDdisplaygets0Vi.e.theoutputisLOW.DerivingBasicGatesUsingNANDLogicGateAsitisalreadydiscussedthatNOTANDgateisauniversalgate.ThismakesitmoreflexiblethatanybasiclogicgatecanbederivedusingaNANDgate.ThebelowsectionexplainsonNANDgatetoderivebasicgates.ANDusingNANDWhentheinputsareconsideredasXandY,thenforanANDgate,thedesiredoutputisX.Y.So,thisBooleanexpressionisderivedusingtheNegatedAndlogicgate.ANDUsingNOTANDGateUsingtheInvolutionprinciple,Y=((X.Y)’)’=X.YORusingNANDWhentheinputsareconsideredasXandY,thenforanORgate,thedesiredoutputisX+Y.ORUsingNOTANDGateSo,thisBooleanexpressionisderivedusingNANDlogicgate.UsingInvolutionprinciple,X+Y=(X+Y)’[(X+Y)]’[(X.X)’(Y.Y)’]’->IdempotencyprincipleNOTusingNANDWhentheinputisconsideredasX,thenforaNOTgate,thedesiredoutputisX’.So,thisBooleanexpressionisderivedusingtheNANDlogicgate.NOTUsingNOTANDGateUsingtheIdempotencyprinciple,(X.X)’=(X)’NANDGateICThecommonlyexistingICsofNANDgateare:InTTLlogicwehave,74LS00Quad2–inputNANDIC74LS10triple3–inputNANDIC74LS20Dual4–inputNANDIC74LS30single8–inputNANDICInCMOSlogicwehave,CD4011Quad2–inputNANDICCD4023Triple3–inputNANDICCD4012dual4–inputNANDIC74LS00ICThisisatwo-inputNANDgateICthathas14pins.TheICconsistsof4independentgateswhereeachgateperformsNegatedANDlogicgatefunctionality.ThesegatesworkonadvancedsilicongateCMOStechnologytogainhigherfunctionalspeedsutilizingminimalpowerandeverygatehasbufferedoutputs.The74LSlogicfamilyisincompatibilitywiththe74HCfamilyinregardstofunctionalityandpin-out.TheinputsofeverygateintheICaresafeguardedfromdamagebecauseofstaticdischargebyinternallypresentdiodeclampstothepowersupplyandground.NANDLogicGateICThefunctionalcharacteristicsof74LS00are:Operatingvoltagerangesbetween4.75Vto5.25VTheLOWandHIGHlevelsofinputvoltagesare0.8Vand2VTheHIGHandLOWlevelsofoutputcurrentsare-0.4mAmpsand8mAmpsTheelectricalcharacteristicsare:TheHIGHandLOW-levelinputcurrentsare20µAmpsand-0.36µAmpsTheHIGHandLOW-leveloutputvoltagesare2.7Vand0.5VTheswitchingcharacteristicsof74LS00are:TheoutputpropagationdelaytimeatthelevelofLOWtoHIGHhasaminimumof3nsandamaximumof10nsataCLof15pFandminimumof4nsandamaximumof15nsataCLof50pFTheoutputpropagationdelaytimeatthelevelofHIGHtoLOWhasaminimumof3nsandamaximumof10nsataCLof15pFandminimumof4nsandamaximumof15nsataCLof50pFVHDLCodeofNANDLogicGateThissectionexplainstheVHDLcodeimplementationforaNOTANDlogicgate:libraryIEEE;useIEEE.STD_LOGIC_1164.ALL;useIEE.STD_LOGIC_ARITH.ALL;useIEEE.STD_LOGIC_UNSIGNED.ALL;entityNANDGateisPort(   X:instd_logic;Y:instd_logic;A:outstd_logic);endNANDGate;architectureNAND1ofNANDGateisbeginA<=XNANDY;endNAND1;NANDGateApplicationsTherearevariousapplicationsofNANDgateinreallifewherefewofthoseareexplainedbelow:UsedinalarmcircuitsthroughlightdetectionradiationEmployedinfreezerwarningbuzzerdevicesNANDlogicgatesareutilizedinautomatictemperatureregulationcircuitsTheseareusedforanalyzingthestatusofthesensorthatisconnectedtovariousdoorsandwindows.Usedinburglaralarms.AdvantagesandDisadvantagesTheNANDgateadvantages,disadvantagesareasfollows:AdvantagesNANDgatesarecost-effectivedevicesandtheyhavemorestoragecapacitiesaspertheirsize.Thisgateoffersgoodreplaceabilitywhichmeansthatwhentheflashmemorygetsdamaged,thenitcanbereplacedwithasuitablecomponent.ThememoryabilityofNANDcansubstitutehugefileslikeUSBdrives,digitalcameras,andtablets.Highenduranceanddurability.DisadvantagesWhencomparedwiththeNORgate,theNANDmemoryarchitectureandspeedarelessreliable.ThisisallaboutanoverviewoftheNANDlogicgate.ThisarticlehasgivendetailedexposuretotheNANDgatetruthtable,circuit,design,applications,andadvantages.Also,knowhowCMOSlogicNANDareconstructedandwhataretheirperformancecharacteristics?RecentPostsWhatisInter-ProcessCommunication:Working,Types&ItsApplicationsWhatisClassDAmplifier:Working,Types,Characteristics&BenefitsMQ2ArduinoGasSensor:PinConfiguration&ItsWorkingWhatisDMAController:Working&ItsApplicationsWhatisLowNoiseAmplifier:Working,Types,Design&ItsApplicationsWhatisAVRMicrocontroller:PinOut,Working&ItsApplicationsWhatisI3CProtocol:Working&ItsApplicationsWhatisIEEE488BusorGPIB:Working&ItsApplicationsWhatisAntennaArray:Architecture&ItsApplicationsWhatisDigitalPotentiometer:Working&ItsApplicationsWhatisYagiUdaAntenna:Design,Working&ItsApplicationsWhatisPreprocessor:Definition,Syntax&ItsCommandsCategoriesArticles(20)Basics(112)Communications(53)Components(39)DigitalElectronics(41)DigitalSignalling(3)Electronics(170)EmbeddedSystems(11)Magnetism(5)Microprocessors(3)Modulation(1)Projects(15)SubscribetoOurNewsletterPleaseleavethisfieldemptyDon’tmissthesearticles!Wedon’tspam!Readourprivacypolicyformoreinfo.Checkyourinboxorspamfoldertoconfirmyoursubscription.CategoryMostReadABOUTContactUsPrivacyPolicy