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DM6467与DDR2之间的PCB布线及信号完整性分析.docx

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DM6467与DDR2之间的PCB布线及信号完整性分析 Introduction TheDM6467isahigh-performancedigitalvideoprocessorthatrequiresahigh-speedmemoryinterfacetosupportitsdataprocessingcapabilities.OneofthemostcommonlyusedmemoryinterfacesforthistypeofprocessorisDDR2memory,whichiscapableofoperatingathighspeeds.However,designingaPCBlayoutthatcansupportsuchhigh-speedsignalsisnotaneasytask,andrequirescarefulconsiderationofthesignalintegrityissues. Inthispaper,wewilldiscussthePCBlayoutandsignalintegrityanalysisfortheDM6467andDDR2memoryinterface.WewillfirstdiscussthePCBdesignguidelinesthatneedtobefollowedforhigh-speedsignals.WewillthendiscusstheDDR2memoryinterfaceanditsrequirements.Finally,wewillanalyzethesignalintegrityoftheDM6467andDDR2memoryinterfaceusingsimulationtools. PCBDesignGuidelines WhendesigningaPCBlayout,thereareseveralguidelinesthatneedtobefollowedtoensureproperfunctionalityoftheboard.Theseguidelinesbecomecriticalwhendealingwithhigh-speedsignals,suchasthoseusedintheDM6467andDDR2memoryinterface.Thefollowingaresomeoftheguidelinesthatneedtobeconsidered: 1.ProperSignalRouting:High-speedsignalsshouldberoutedinastraightlinewithalow-impedancepathtominimizesignalreflectionsandcrosstalk.Thesesignalsshouldalsoavoidanysharpcornersorbends. 2.GroundPlane:Asolidgroundplaneshouldbeusedtoprovidealow-impedancereturnpath,whichiscriticalformaintainingsignalintegrity.Thegroundplaneshouldbeplaceddirectlybelowthesignallayer. 3.DifferentialPairRouting:Differentialpairsshouldberoutedascloselytogetheraspossibletominimizetheelectromagneticinterference(EMI).Thedifferentialpairlengthshouldbematchedtomaintainsignalbalance. 4.ControlledImpedance:High-speedsignalsshouldbedesignedwithcontrolledimpedancetracestominimizereflectionandmaintainsignalintegrity.Theimpedanceshouldmatchthecharacteristicimpedanceofthetransmissionline. DDR2MemoryInterface TheDDR2memoryinterfaceisahigh-speedinterfacethatoperatesatclockfrequenciesofupto533MHz.Theinterfaceconsistsofseveralsignalsthatneedtobecarefullyroutedanddesignedtomaintainsignali