cadence allegro si培训课件lesson8

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1、Lesson7DifferentialPairDesignExplorationCreateaDifferentialPair.AssignaDifferentialPairSignalModel.ExtractaDifferentialPairTopology.AnalyzeaDifferentialPairTopologyinSigXplorer.AssignDifferentialPairConstraintsinSigXplorer.ApplyaDifferentialPairECSetintheConstra

2、intManager.RouteaDifferentialPair.ExtractaPost-RouteDifferentialPairTopology.WhatisDifferentialSignal?Thebasicfeaturesofdifferentialsignalsare:Samesetofinformation(bothnon-invertedandinverted)issentfroma(differential)driverovertwotracestoa(differential)receiverLo

3、wervoltageswingsallowed,resultinginfastercircuitsReducedpowerconsumptionReducedelectro-magneticinterference(EMI)ReducedsensitivitytocrosstalkCommon-moderejectionofferedatthereceiver’sendIBISDifferentialDriversTwo-pinmodelDifferentialPairBufferDelayThetestfixturef

4、orcalculatingBufferDelayisobtainedfromthedatasheet.TestFixtureasgiveninthedatasheetTwo-pinESpicemodelIBISDifferentialReceiversTypesofDifferentialPairsinAllegroPCBSIDifferentialPairsareoftwotypes:UserdefinedCreatedinteractivelythroughtheAllegroPCBSIuserinterfaceor

5、theConstraintManager.Canbemodifiedordeleted.ModeldefinedCreatedwhenapackagemodelcharacterizesdifferentialpins.Noteditable(read-only).CreateDifferentialPairUsingAllegroPCBSIUIFromAllegroPCBSImainmenuselectLogic>AssignDifferentialPairCreateDifferentialPairUsingCons

6、traintManagerFromConstraintManagermainmenuselectObjects>Create>DifferentialPairAssigningDifferentialPairSignalModelsFromAllegroPCBSImainmenuselectAnalyze>SI/EMISim>ModelThedifferentialpairscreatedusingAllegroortheConstraintManagerarephysicalassignmentonly.Toextra

7、ctthedifferentialpairtopology,thedifferentialpairsignalmodelwithmatingpinspecificationsneedstobeassigned.Ifasignalmodelisnotassignedforthedifferentialpair,thesimulationwillbesingle-Xnet-based.PreferencetoExtractUnroutedDifferentialPairTopologyFromAllegroPCBSImain

8、menuselectAnalyze>SI/EMISim>PreferencesIfselected,idealTLineCoupledmodelwillbeused.ExtractingUnroutedDifferentialPairTopologyExtractedIdealTlineCoupledmodelCus