第十四章IO环设计-1

第十四章I/O设计及封装（一）

OutlinesBasicstructureofI/OcellsNoiseCancellationESDProtectionSchemeI/OringdesignPackageSelection

OutlinesBasicstructureofI/OcellsNoiseCancellationESDProtectionSchemeI/OringdesignPackageSelectionPerformancewithDie,Package,BoardThreemainkillersofperformancePowersupplynoiseReferenceclocknoiseSignalintegrityThesechallengesarerelevantatthedie,package,boardandsystemlevelThesechallengeshaveexistedatlowerspeedsbutdramaticallyincreaseinhighspeedsI/OCellI/OCell–ConnectCoretoPackageSupplyCellmaxcurrentAnalogcelllowvoltagedropDigitalcellInput:w/wopull-up,pull-down,schmittTriggerOutput:drivingstrength,highspeed,lownoiseBi-directionalinput/outputSpecialCellpower-cutI/Ocell,Cornercell……CategoryofI/OCellBasicStructureofI/OcellsOutputCell:Pre-driverProvideproperlogicoperationforIOcircuitsLevelshift(e.g.1.8vcorevoltage,3.3vIOvoltagefor0.18uprocess)Bigpost-driverIObuffer

ProvidebigdrivingcapabilityProvideESDprotectionabilityESDprotectionInputCell:Inputbufferw/wonoiseimmunity(SchmittTrigger)W/wopullup/downfunctionESDprotectionBasicStructureofI/Ocell–Cont.AnalogInputCell:ESDprotectionwithoutinputresisterPower(VDD/VSS):BigESDprotectioncellfortheI/Oring.Othercells:Fillercell:provideconnectionforthepower/groundringESDprotectionCellDecouplingcellI/OLayoutBondingpadI/OfillercellAsstandardcellHeightPowerlinesESDLatch-up

OutlinesBasicstructureofI/OcellsNoiseCancellation

ESDProtectionSchemeI/ORingPackageSelectionNoiseproblematHighSpeedI/OQ:Cansimplyincreasedriversizetomeethighspeedrequirement?A:No!ProblemswhenoutputsignalathighspeedRingingBounceEMINoisesCausedbySwitchingActivity

onOutput

RingingRinging:OscillationonthesignalsattheswitchingpinsBounceEMI:ElectromagneticInterferenceEMIradiationiscausedbyHigh-frequencycurrentbutnotbyvoltageperturbation.EMI–cont.Itisextremelydangerousforawirelesssystem.TheUltimatenoisesourceisinthechip.ControllingEMIatthechiplevelisbecomingmorecritical.SpecialdesigninI/OcellandI/Oring

NoiseControlI/OcellInputwithnoiseimmunitycircuitOutputwithslewratecontrolcontrollingRinging,BounceandEMI

InputNoiseImmunitySchmittTriggercircuitiscommonlyusedtoincreasenoiseimmunityfor“lowspeed”inputDrawback:largedelayontheinputsignal.Commonlyusedforslowserialmodules,e.g.I2C,SPIOutputNoiseControlCircuitSlewratecontrolRingingcancellationBouncereductionEMIcontrolRingingCancellationandBounceReductionExamplecircuit:

RingingCancellation–cont.ElectromagneticInterferenceControlEMIradiationiscausedbyHigh-frequencycurrent(I)notbyvoltage(V)perturbation.Buttheslewrateofthesignal,dV/dt,reflectthehigh-frequencycurrent.ControllingSignalParameters,RiseandFalltimes,toreducehighfrequencyharmonicsofsignalsandcontrolsspectrumdensity:BounceReductionDesignbouncedetectandcancellationcircuit

SeetheindicationinRingingCancellationReducethenumberofI/Oswhichsharesonepairofsupplies

MoresuppliesforfastI/Os;lesssuppliesforslowI/Os.Arrangethepinordertoavoidswitchingatthesametime

Example:puttheI/Ocellsforaddresssignalanddatasignalalternativelyastheywillnotswitchingatthesametime.Separatepowerdomains

Separatethepowerdomainaccordingtopadfunctions.Analogbank,fastdigitalbank,slowdigitalbank......AddDecouplingcapacitorsbetweenI/Ocells

adddecouplingcaponunusedemptyspace

OutlinesBasicstructureofI/OcellsNoiseCancellationESDProtectionSchemeI/ORingPackageSelectionElectroStaticDischarge(ESD)ProtectionICwasdamagedduetoElectricalOverstressESDTestStandardStandard:JEDECESDstandardHumanBodyModel(HBM)MachineModel(MM)ChargeDeviceModel(CDM)BasicESDrequirementforproductsHBMMMCDMPerformance2000V200V1000VOK10000V1000V2000VSupperESDProtectionReference:

JAMESE.VINSONANDJUINJ.LIOU,SENIORMEMBER,IEEE,

ElectrostaticDischargeinSemiconductorDevices:AnOverview,

ElectrostaticDischargeinSemiconductorDevices:ProtectionTechniques,IEEE,1998.ESDTestModelHumanBodyModel(HBM)ApplyalargevoltageHBMtest:SchematicandcurrentESDTestModel-contMachineModel(MM)Example:testmachinehandlerApplybigcurrentMMtest:SchematicandcurrentESDTestModel-contChargeDeviceModel(CDM)ChargeaccumulatedinsideofICCDMisthemostdangerouscasetodamagertheICESDTestCasesI/OtopowerpinsESDTestCases–cont.SupplypinsESDTestCases-contIOpin-to-pinESDtestESDProtectionCircuitConcept:

provideESDpaths(short-circuitpath)inordertopreventtheESDcurrentintointernalcircuitESDProtectionSchemeInputprotectionOutputprotectionVDDtoVSSESDProtectionNetworkGlobalESDProtectionGlobalESDprotectionInputESDProtectionCircuitTwocommonlyusedESDprotectioncircuitsOutputESDProtectionCircuitTwocommonlyusedESDprotectioncircuitsESDProtectionNetworkVDDtoVSSESDpathESDvoltageacrossVDDandVSScanbequicklydischargedthroughtheshort-circuitpathofturn-onNMOSEDScellorP/GcellESDProtectionNetwork–cont.ProvideESDprotectionpathbetweendifferentpower/groundlevels

OutlinesBasicstructureofI/OcellsNoiseCancellationESDProtectionSchemeI/OringPackageSelectionI/ORingConnectionMakeconnectiontopowerandgroundlinesMakeaglobalESDprotectDesignconsiderations:DiesizeimpactBoundingabilityESDprotectionNoiseimmunityDieSizePad-limitedvs.core-limitedDieSize–cont.IOCellswithFillersinIn-lineBondingForcore-limitedAbuttedIOCellsinStaggeredBonding

Forpad-limitedBondingCapa