Effective Power Ground Plane Decoupling for PCB.pdf

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1、EffectivePower/GroundPlaneDecouplingforPCBDr.BruceArchambeaultIBMResearchTrianglePark,NCBarch@us.ibm.comwww.eda365.comOctober2007PowerPlaneNoiseControl“GroundBounce”www.eda365.comOctober2007Dr.BruceArchambeault2Power/Ground-ReferencePlaneNoise•MustconsiderTWOMajorFactors–EMC--Reducen

2、oisealongedgeofboardfromICsomewhereelse–Functionality--ProvideICwithsufficientcharge•DecouplingstrategiesareFULLofMyths–Considerthephysics–Don’tforgetInductance!www.eda365.comOctober2007Dr.BruceArchambeault3SourceofPower/Ground-ReferencePlaneNoise•PowerrequirementsfromICduringswitchi

3、ng•CriticalNetcurrentsroutedthroughviawww.eda365.comOctober2007Dr.BruceArchambeault4PowerBusSpectrumClockDriverIDT74FCT807www.eda365.comOctober2007Dr.BruceArchambeault5NoiseInjectedbetweenPlanesDuetoCriticalNetThroughVia20cmI/OPin/ViaSignalVia30cmFR42=4.2Losstan=0.02www.eda365.comrOc

4、tober2007Dr.BruceArchambeault6TransferFunctionfromViatoI/OPinTransferFunctionFromVia-to-Via20x30cmBoard05milSeperation10milSeperation15milSeperation-1025milSeperation35milSeperation-20-30-40TransferFunction(dB)-50-60-701.E+08www.eda365.com1.E+091.E+10Frequency(Hz)October2007Dr.BruceA

5、rchambeault7DecouplingMustbeAnalyzedinDifferentWaysforDifferentFunctions•EMC–Resonancebigconcern–RequiresSTEADY-STATEanalysis•FrequencyDomain–Transferfunctionanalysis•EliminatenoisealongedgeofboardduetoASIC/IClocatedfarawaywww.eda365.comOctober2007Dr.BruceArchambeault8DecouplingMustb

6、eAnalyzedinDifferentWaysforDifferentFunctions•ProvideChargetoASIC/IC–RequiresTRANSIENTanalysis–ChargewillNOTtravelfromfarcornersoftheboardfastenough–Localdecouplingcapacitorsdominate–ImpedanceatASIC/ICpinsimportantwww.eda365.comOctober2007Dr.BruceArchambeault9Steady-StateAnalysis•Mea

7、surementsandSimulations•TestBoardwithDecouplingcapacitorsevery1”squarewww.eda365.comOctober2007Dr.BruceArchambeault10TestBoardPorts12”11”#1#2#3#4#510”9”#6#7#8#9#105”#11#12#13#14#151”1”3”Figure1www.eda365.com6”9”October2007Dr.BruceArchambeault11S21UsedforDecoupling“Goodness”•RatioofPo

8、wer‘out’topo