PCB-Insertion-Loss-Introduction

PCBInsertionLossIntroduction主講人：Halee日期：2011/03/11Agenda‹InsertionLoss的定義及發展現狀‹InsertionLossS-Parameter的理解‹InsertionLoss測試方法探討與介紹‹InsertionLoss影響因素及控制方InsertionLoss定義InsertionLoss:TheLossinloadpowerduetoinsertionofacomponent,connector,ordeviceatsomepointinatransmissionsystem.Generallyexpressedastheratio-indecibels-ofthepowerreceivedattheloadbeforeinsertionoftheapparatus,tothepowerreceivedattheloadafterinsertion.InsertionLoss定義†Forouranalysis,insertionlossistypicallytheeffectonasignalasitrunsfromaPCBintoaconnector.†Insertionlossisoftenduetoadifferenceofimpedance,orimpedancemismatch,fromPCBtoconnector.TheInsertionLossofaline†TheInsertionLossofalineistheratioofthepowerreceivedattheendofthelinetothepowertransmittedintotheline.†IfthepowertransmittedbythesourceisPTandthepowerreceivedbytheloadisPR,thentheinsertionlossisgivenbyPRdividedbyPT.Clearlythisratioisalwayslessthanone,soitwouldbemorecorrecttocallthepropertyInsertionGain.ItisoftencalledAttenuation.†FormaximumpowertransfertheInsertionLossshouldbeassmallaspossible.InotherwordstheratioPR/PTshouldbeascloseto1aspossible,whichindecibelsmeansascloseto0dBaspossible.IL=10Lg(PR/PT)InsertionLoss&AttenuationInsertionLoss:多指功率方面的损失,是一个频域参数，表征的是信号线对输入信号不同频率成分（谐波成分）的衰减量。如USB3.0Cable在2.5GHz傳輸時的損耗。Attenuation:指信号电压的幅度相对原信号幅度的变小。如理想變壓器InsertionLoss發展現狀†TestMethodstoDeterminetheAmountofSignalLossonPrintedBoards(PBs)-----IPC-TM-6502.5.5.12†ImentionedthatinthecomingmonthsI'dbelookinginmoredetailathowthePCBindustrywouldneedtoadapttoincreasingrequirementsforinsertionlosstesting.ThiscolumndiscussesthegradualadaptationnecessaryforPCBfabricatorsasmoreandmoresiliconfamiliesdrivetheindustrytowardtherequirementforin-housemeasurementofinsertionloss.------Tuesday,September14,2010MartynGaudionPolar’sCEOPCBDesign†Newlossmeasurementrequirementcomingforcircuitboardfabshops-------EricBogatin5/26/20108:36PMEETimesJustasmeetingacharacteristicimpedancespechasbecomeastandardrequirementforallcircuitboardshops,anddifferentialimpedanceisbitdditItlitllithilittInsertionLoss發展現狀Fortoday'shighspeedinterfaces,PCBtraceinsertionloss(S21forsingle-endedsignals,SDD21fordifferentialsignals)isacriticalparameterforsignalfidelity,justasimpedancehasbeenforseveralyears.Excessivelyhighinsertionlosscandramaticallyattenuatethesignalinlongchannels,reducingeyeheightandincreasingjitter.Insertionlossthatistoolowcancreateproblemsforshort,reflectivechannels,sincethereflectionsarenotsufficientlydamped.MeasuringandcontrollingPCBinsertionlossiscriticaltoasuccessfulplatformdesign.-----IntelRomleyPlatformDesignGuideJune2010Agenda‹InsertionLoss的定義及發展現狀‹InsertionLossS-Parameter的理解‹InsertionLoss測試方法探討與介紹‹InsertionLoss影響因素及控制方法S-Parameter定義S参数-ScatteringParameters,通常用来描述工作在类似于RF和微波频率的高频下的n端口网络，是测量“传输网络”的反射功率和传输功率，最终测量结果是和频率相关的.S参数有幅值的S参数和相位的S参数。一般地说，幅值测量是以dB表示，相位是以角度表示。S参数的表达方式S参数的表达方式多种多样:†在数学表达上是一个矩阵形式。†在图形表达上，则是一个横轴表示频率，纵轴表示散射程度的曲线。†在仿真中，S参数就是代表了器件特性的一种模型，这个模型在仿真应用中的“输入”是一个叫touchstone格式的文件。二端口S參數（一）二端口S參數（二）†S11=b1/a1=反射功率/入射功率。S11表示在输出端端接匹配情况下的输入端反射系数，通常被称为回波损耗（returnloss）。†S21=b2/a1=输出功率/输入功率。S21表示在输出端端接匹配情况下的前向传输增益（系数），通常被称为插入损耗(insertionloss)。四端口S參數（一）四端口S參數（二）†四端口网络S参数中，S11，S22，S33，S44分别表示各端口的回波损耗/反射系数。S21，S12，S34，S43表示插入损耗/传输增益。S13，S31，S24，S42表示近端串扰（nearendcrosstalk）。S14，S41，S23，S32表示远端串扰（farendcrosstalk）。图七表示了串扰的物理意义。近端串扰表示在某端口施加激励，在相近的一端的另外一个端口耦合到的信号。远端串扰的含义就是在较远的一端耦合到的信号。混合模式的S参数†差分系统并不是完美的,构成差分信号的两个单端信号本身的不平衡，两个通道的长度不相等,耦合不紧密等都会导致能量由差模向共模转换。由于实际的差分信号总是由差模信号和共模信号组成。†混合模式S参数从物理意义上理解正是描述了成对的两根线对两个信号之和（共模）和两个信号之差（差模）的分别有什么样的响应。S參數-Sumup…†S-parametersareapowerfulwaytodescribeanelectricalnetwork†S-parameterschangewithfrequency/loadimpedance/sourceimpedance/network†S11isthereflectioncoefficient†S21describestheforwardtransmissioncoefficient(respondingport1st!)†S-parametershavebothmagnitudeandphaseinformation†Sometimesthegain(orloss)ismoreimportantthanthephaseshiftandthephaseinformationmaybeignored†S-parametersmaydescribelargeandcomplexnetworksAgenda‹InsertionLoss的定義及發展現狀‹InsertionLossS-Parameter的理解‹InsertionLoss測試方法探討與介紹‹InsertionLoss影響因素及控制方法‹InsertionLoss對PCBLayout要求InsertionLossIPC規範InsertionLossIPC方法比對†EBWEffectiveBandwidth(EBW)methodThismethodisnotintendedforrigorousanalysisofthesignalattenuationofPCBinterconnectsbutforasimpleproductiontest.†RootImpulseEnergy(RIE)initiallyshowedpromise,butfelldownowingtoalackofstandardisation.†ShortPulsePropagation(SPP)hasgainedsomeadoption;SPPiscapableofextractingverygooddata,butveerstowardthemorecomplextosetup.†SET2DILproposedatDesignCon2010showspromiseasrelativelystraight-forwardtoadoptandhasthebenefitofmeasuringdifferentialinsertionlosswithasingleendedTDR--hence,Single-EndedTDRtoDifferentialInsertionLoss(SET2DIL).InsertionLossEquipmentVenderSolution†Tektronix方案:TektronixDSA8200/TDS8000B180E10/80E04Module2P80318Probe2IConnectSWwithDongle1†Agilent方案:AgilentE5071C/20GHz14-portTestSet,300kHzto20GHzwith1BiasTees(E5071C-4K5)Timedomainanalysis(E5071C-010)1EnhancedTimeDomainAnalysis(E5071C-TDR)InsertionLossIntelSolutionInsertionLossIntelSolutionzSET2DILTektronixDSA8200/TDS8000B180E10/80E04Modul