Integratedcircuitdesign
Integratedcircuitdesign(English:Integratedcircuitdesign,ICdesign),accordingtothecurrentintegratedcircuitdesignScale,whichcanalsobereferredtoasVLSIdesign(VLSIdesign),referstothedesignprocessforintegratedcircuitsandverylargescaleintegratedcircuits.
Integratedcircuitdesigninvolvestheestablishmentofinterconnectionmodelsofelectronicdevices(suchastransistors,resistors,capacitors,etc.)anddevices.Alldevicesandinterconnectsneedtobeplacedonapieceofsemiconductorsubstratematerial,andthesecomponentsareplacedonasinglesiliconsubstratethroughasemiconductordevicemanufacturingprocess(suchasphotolithography,etc.)toformacircuit.Themostcommonlyusedsubstratematerialissilicon.Thedesignerwillusetechnicalmeanstoelectricallyisolatethevariousdevicesonthesiliconsubstratefromeachothertocontroltheelectricalconductivitybetweenthevariousdevicesontheentirechip.PNjunctions,metaloxidesemiconductorfieldeffecttransistors,etc.constitutethebasicstructureofintegratedcircuitdevices,whilethecomplementarymetaloxidesemiconductorcomposedofthelatterhasbecomeadigitalintegratedcircuitduetoitsadvantagesoflowstaticpowerconsumptionandhighintegration.Thebasicstructureoflogicgates.Designersneedtoconsidertheenergydissipationoftransistorsandinterconnections.Thisisdifferentfromthepreviousdiscreteelectronicdevicestobuildcircuits.Thisisbecauseallthecomponentsofanintegratedcircuitareintegratedonasiliconchip.Electromigrationandelectrostaticdischargeofmetalinterconnectsaregenerallyharmfultodevicesonmicrochips,andthereforearealsoissuesthatneedtobepaidattentiontoinintegratedcircuitdesign.
Asthescaleofintegratedcircuitscontinuestoincrease,itsintegrationhasreachedthedeepsubmicronlevel(featuresizebelow130nanometers),andthenumberoftransistorsintegratedonasinglechiphasapproachedonebillion.Duetoitscomplexity,thedesignofintegratedcircuitsoftenrequirescomputer-aideddesignmethodologyandtechnicalmeanscomparedwithsimplercircuitdesigns.Theresearchscopeofintegratedcircuitdesigncoverstheoptimizationofdigitallogicindigitalintegratedcircuits,therealizationofnetlists,thewritingofhardwaredescriptionlanguagecodesattheregistertransferlevel,theverification,simulationandtiminganalysisoflogicfunctions,andthedistributionofcircuitsinthehardware.Theplacementofoperationalamplifiers,electronicfiltersandotherdevicesinthechipinanalogintegratedcircuitsandtheprocessingofmixedsignals.Relatedresearchalsoincludeselectronicdesignautomation(EDA)ofhardwaredesign,computer-aideddesign(CAD)methodology,etc.,whichareasubsetofelectricalengineeringandcomputerengineering.
Fordigitalintegratedcircuits,designersaremoreatthehigh-levelabstractionlevel,thatis,theregistertransferlevelorevenhighersystemlevel(somepeoplealsocallitthebehaviorlevel),usinghardwaredescriptionlanguageOrhigh-levelmodelinglanguagetodescribethelogicandtimingfunctionsofthecircuit,andlogicsynthesiscanautomaticallyconvertthehardwaredescriptionlanguageattheregistertransferlevelintoanetlistatthelogicgatelevel.Forsimplecircuits,designerscanalsousehardwaredescriptionlanguagetodirectlydescribetheconnectionbetweenlogicgatesandflip-flops.Afterfurtherfunctionalverification,layout,androutingofthenetlist,GDSIIfilesforindustrialmanufacturingcanbegenerated,andfactoriescanmanufacturecircuitsonwafersbasedonthefiles.Thedesignofanalogintegratedcircuitsinvolvesamorecomplexsignalenvironment,requireshigherengineers'experience,andthedegreeofautomationofitsdesignisfarlessthanthatofdigitalintegratedcircuits.
Aftercompletingthefunctionaldesignstepbystep,thedesignruleswillspecifywhichdesignsmeetthemanufacturingrequirementsandwhichonesdonot,andthisruleitselfisalsoverycomplicated.Theintegratedcircuitdesignprocessneedstocomplywithhundredsoftheserules.Undercertaindesignconstraints,thelayoutandroutingofthephysicallayoutofanintegratedcircuitisessentialtoobtainidealspeed,signalintegrity,andreducechiparea.Theunpredictabilityofsemiconductordevicemanufacturingmakesintegratedcircuitdesignmoredifficult.Inthefieldofintegratedcircuitdesign,duetothepressureofmarketcompetition,electronicdesignautomationandotherrelatedcomputer-aideddesigntoolshavebeenwidelyused.Engineerscanperformregistertransfer-leveldesign,functionalverification,statictiminganalysis,andphysicaldesignwiththeassistanceofcomputersoftware.Andotherprocesses.
Application-specificintegratedcircuit
Application-specificintegratedcircuit(English:Application-specificintegratedcircuit,abbreviation:ASIC)referstointegratedcircuitswithspecialspecificationsthatarecustomizedaccordingtodifferentproductrequirements;onthecontrary,non-customizedonesareapplication-specificstandardproductintegratedcircuits.
Application-specificintegratedcircuitsaredesignedandmanufacturedaccordingtotherequirementsofspecificusersandtheneedsofspecificelectronicsystems.SincetheproductioncostofasingleASICchipisveryhigh,iftheshipmentvolumeissmall,theuseofASICsisnoteconomicallyaffordable.Inthiscase,programmablelogicdevices(suchasfieldprogrammablelogicgatearrays)canbeusedastargethardwaretoimplementintegratedcircuitdesign.Inaddition,programmablelogicdeviceshaveuser-programmablefeatures,sotheyaresuitableforprototypesbeforemassproductionoflarge-scalechipsfordebuggingandothertasks.However,thedegreeofoptimizationofprogrammablelogicdevicesintermsofareaandspeedisnotasgoodasthatoffullycustomizedintegratedcircuits.
Generally,theROMandRAMoftheASICaremasked(MASK)beforeleavingthefactory,suchasthecommonlyusedinfraredremotecontroltransmitterchipisthiskindofchip.
Application-specificintegratedcircuitsarecharacterizedbytheneedsofspecificusers,withmanyvarieties,smallbatches,andshortdesignandproductioncycles.Itisaproductofcloseintegrationofintegratedcircuittechnologyandspecificuser'scompletemachineorsystemtechnology.Comparedwithgeneralintegratedcircuits,ithastheadvantagesofsmallersize,lighterweight,lowerpowerconsumption,improvedreliability,improvedperformance,enhancedconfidentiality,andcostreduction.
Full-customization
Full-custom(English:Full-custom)designapproachisawayofintegratedcircuitdesign.Thisapproachrequiresdesignerstocompletethedetailedlayoutofalltransistorsandinterconnects,unlikeanotherdesignapproach—semi-custom(semi-custom)designmethod,Insteadofstartingthedesignonthebasisoftransistors,butbyusingthealreadydesignedsub-circuitstocompletethedesignoftheentirecircuit.Infact,thestandardcomponentsusedinthesemi-customdesignapproacharealsocompletedbythefullcustomdesignmethod,andthedesignofaseriesofsuchstandardcomponents(usuallycalled"standardcelllibrary"and"processlibrary")willcostalotofmoney.Longtime.
Becauseofthehighprecisionofthedesign,thefullcustomdesigncanoptimizetheperformanceofthechiptothegreatestextentwithoutwastingtoomuchchipresources.However,thisdesignmethodusuallyconsumesmoremanpowerandtimecostthansemi-customdesign.Therefore,onlythoseintegratedcircuitproductsthatneedtobeputintomassproduction(suchasmicroprocessors,etc.)willusethefullcustomizationmethod,becauseitisnoteconomicalforasinglechiptousethefullcustomizationmethod.
Thecostrequiredforthedesignandmanufactureofintegratedcircuitsisafactorthatneedstobeconsidered.Manufacturingphotomasksforphotolithography(oneoftheprocessesofconvertingabstractintegratedcircuitlayoutsintoactualhardwarecircuits)isquiteexpensive,andtheauthorizationofrelatedelectronicdesignautomationsoftwarewillalsocostobjectivefunds.
FieldProgrammableGateArray
Overview
FieldProgrammableGateArray(English:FieldProgrammableGateArray,abbreviationForFPGA),itisaproductoffurtherdevelopmentonthebasisofprogrammablelogicdevicessuchasPAL,GAL,andCPLD.Itemergedasasemi-customcircuitinthefieldofapplicationspecificintegratedcircuits,whichnotonlysolvestheshortcomingsoffullycustomizedcircuits,butalsoovercomestheshortcomingsofthelimitednumberofgatecircuitsoftheoriginalprogrammablelogicdevice.
Logiccircuitsdescribedinhardwaredescriptionlanguages(VerilogorVHDL)canbequicklyburnedtoFPGAfortestingusinglogicsynthesisandlayoutandroutingtoolsoftware.ThisprocessisamodernintegratedcircuitdesignMainstreamofverifiedtechnology.Theseprogrammablelogicelementscanbeusedtoimplementsomebasiclogicgatedigitalcircuits(suchasANDgates,ORgates,XORgates,NOTgates)ormorecomplexcombinatoriallogicfunctions,suchasdecoders.InmostFPGAs,theseeditablecomponentsalsocontainmemorycomponents,suchasflip-flops(Flip-flop)orothermorecompletememoryblockstoformsequentiallogiccircuits.
SystemdesignerscanconnectthelogicblocksinsidetheFPGAthrougheditableconnectionsasneeded.It'sasifabreadboardisplacedinachip.ThelogicblocksandconnectionsofafinishedFPGAafterleavingthefactorycanbechangedaccordingtotheneedsofthedesigner,sotheFPGAcancompletetherequiredlogicfunctions.
FPGAsaregenerallyslowerthanapplication-specificintegratedcircuits(ASICs),unabletocompletemorecomplexdesigns,andwillconsumemorepower.However,FPGAhasmanyadvantages,forexample,itcanbefinishedquickly,anditsinternallogiccanberepeatedlymodifiedbythedesignertocorrecterrorsintheprogram.Inaddition,thecostofdebuggingusingFPGAisrelativelylow.ManufacturersmayalsoprovidecheapFPGAproductswithlimitededitingcapabilities.Becausethesechipshavepooreditability,thedevelopmentofthesedesignsiscompletedonacommonFPGA,andthenthedesignistransferredtoachipsimilartoanapplicationspecificintegratedcircuit.Insomeindustrieswherethetechnologyisupdatedrelativelyquickly,FPGAisalmostanecessarycomponentintheelectronicsystem,becausebeforemasssupply,itmustquicklyseizethemarket,andtheconvenienceandflexibilityofFPGAisveryimportantatthistime.
Inordertoachievetheabovepurpose,anothermethodistouseacomplexprogrammablelogicdevice(CPLD)insteadofanFPGA.TheCPLDisbrieflyintroducedbelowandcomparedwithFPGA.
Asearlyasthemid-1980s,FPGAshavetakenrootinprogrammablelogicdevicedevices.BothCPLDandFPGAincludearelativelylargenumberofeditablelogicunits.ThedensityofCPLDlogicgatesisbetweentensofthousandstotensofthousandsoflogicunits,whileFPGAsareusuallytensofthousandstoseveralmillion.
ThemaindifferencebetweenCPLDandFPGAistheirsystemstructure.ThestructureofCPLDhascertainlimitations.Thisstructureconsistsofoneormorelogicalgroupingsofeditableresultsandarelativelysmallnumberoflockedregisters.Thisresultisalackofeditingflexibility,butitsadvantageisthatitsdelaytimeiseasytopredict,andtheratiooflogicalunitstoconnectedunitsisrelativelyhigh.TheFPGAhasalargenumberofconnectionunits,sothatalthoughitcanbeeditedmoreflexibly,thestructureismuchmorecomplicated.
AnotherdifferencebetweenCPLDandFPGAisthatmostFPGAscontainhigh-levelbuilt-inmodules(suchasaddersandmultipliers)andbuilt-inmemory.AnimportantdifferencebroughtaboutbythisisthatmanynewFPGAssupportcompleteorpartialin-systemreconfiguration.Allowtheirdesigntochangewithsystemupgradesordynamicreconfiguration.SomeFPGAsallowpartofthedevicetobere-edited,whileotherpartscontinuetooperatenormally.
Basiccomposition
StaticRandomAccessMemory(SRAM)-Basedonstaticmemorytechnology.Programmableandre-programmableinthesystem(re-programmable).Needexternalbootdevices(externalbootdevices).CMOS.
Antifuse-canbeburnedonce.UsuallyCMOS.
PROM(OneTimeProgrammableEPROM)-Programmableread-onlymemorytechnology,whichcanbeprogrammedonce.Useplasticpackage,nowindow,cannotclearthecontent.
EPROM-Clearableprogrammableread-onlymemorytechnology,withwindows,thecontentscanbeclearedbyultravioletradiation.
EEPROM-Programmableread-onlymemorytechnologythatcanbeelectricallyerased,andthecontentcanbeerasedwithelectricalsignals.
Flashmemory-aspecialtypeofEEPROM.
Fuse-canbeprogrammedonce,usuallybipolar.