眼图的原理学习

眼图的原理学习第1页/共72页2023/4/202高速串行总线和传统并行总线对比第2页/共72页2023/4/203高速串行总线－新兴标准和数据速率FibreChannel4X4.25Gb/s4.25Gb/s(1X)FBDIMM4.8Gb/s>500Gb/s

(14lanesx8channels)第3页/共72页2023/4/204眼图定义第4页/共72页2023/4/205一般信号与眼图的区别第5页/共72页2023/4/206眼图特征定义

第6页/共72页2023/4/207眼图特征定义第7页/共72页2023/4/208眼图形成示意第8页/共72页2023/4/209眼图在示波器上的形成第9页/共72页2023/4/2010眼图的CLK采样示波器的CLK通常可能是用户提供的时钟,恢复时钟,或者与数据信号本身同步的码同步信号.实时示波器通过一次触发完成所有数据的采样,不需附加的同步信号和触发信号.通常通过软件PLL方法恢复时钟.TektronixRT-Eye软件即使用此方法.TDS8200ETScope(20GHz80E03)TDS6154CRTw.DSP第10页/共72页2023/4/2011眼图与CLK－时钟速率提高,眼图质量下降125MCLK250MCLK500MCLK第11页/共72页2023/4/2012示波器上的眼图提供串行总线数据的丰富信息:通过比较发送端和接收端的眼图质量可以分析出信号传输的问题

眼高,眼底,眼宽上升时间下降时间模板测试第12页/共72页2023/4/2013眼图与系统速率水平时域上关联因素

Transition(rise)timeAperturetimeTiminguncertainty,skewandjitter垂直域幅度损耗和噪声Unimparedbitedge第13页/共72页2023/4/2014眼图和传输质量LargereyeopeningmeansgreatertolerancetoamplitudeandtimingvariationsLargereyeopeningtranslatestosimplersystemdesignandbetterreliabilityWidertransitionregionindicatesgreaterjitterandhigherbiterrorrateBesterrorrateobtainedwhendecisionpointisnearcenteroftheeye第14页/共72页2023/4/2015PValuesPTopmean,themeanvalueofPTopPTopsigma,thestandarddevofPTopPBasemean,meanvaluewithinaperturePBasesigma,stddevofPBaseinaperturePcrossmean,verticalmeanofcrossingpt.TValuesTcrossmean,horizmeanofcrossingpt.Tcrosssigma,horizstddevofcrossingpt.Tcrosspk-pk,horizpk-pkofcrossingpt.TheEyeAperturedefaultstothecenter20%oftheintervalfromTCross1toTCross2butissettablefrom0to100%眼图测量特征量TCross1TCross2PCross1PCross2EyeAperturePBasePTop第15页/共72页2023/4/2016

JitterRMS=TCross1sigmaJitterPk-Pk=TCross1pk-pkExtinctionRatio=PTopmean/PBasemean(ERalsoindBand%)QualityFactor=(PTopmean-PBasemean)/(PTopsigma+PBasesigma)EyeHeight=(PTopmean-3*PTopsigma)-(PBasemean+3*PBasesigma)EyeWidth=(TCross2mean-3*TCross2sigma)-(TCross1mean+3*TCross1sigma)CrossingPercent,DutyCycleDistortion,Noisepk-pk,NoiseRMS,SNR眼图测量特征量TCross1TCross2PCross1PCross2EyeAperturePBasePTop第16页/共72页2023/4/2017眼图的测量近端远端采样点串扰随机抖动确定性抖动码间干扰(ISI)占空比失真(DCD)正弦抖动(SJ)无关联的

幅度损耗第17页/共72页2023/4/2018串行总线:BasicblocksTransmittersInterconnects(paths)ReceiversTx+-path+-+-path+-+-path+-+-+-RcvDifferentialTransmitterDual-coax

differentialcableTwisted-pairdifferentialcableCoupled-pairtracesoncircuitboard(backplanes)DifferentialReceiver第18页/共72页2023/4/2019高速串行总线－信号线上不仅包含数据信息还包含时钟信息pathTx+-+-+-+-RcvDifferentialserialdataissentwithoutanyclocksignalacrosstheinterconnecttothereceiverCDRDATADATACLOCKAclockis“recovered”fromtheincomingdataatthereceiverthroughaclockanddatarecoverycircuit(CDR).第19页/共72页2023/4/2020高速串行总线－数据传输过程中干扰因素增多path+-+-path+-+-Tx+-path+-+-+-RcvTx+-path+-+-+-Rcvpath+-+-Tx+-path+-+-+-Rcvpath+-+-Transitionpointsofteninvolvecombinationsofsolderjoints,circuitboardvias,andconnectors:theseallcanhavesubstantialeffectonthetotallinkperformance.第20页/共72页2023/4/2021高速串行总线－损耗速率越高互连距离越长,损耗越大ReferenceMaximNoteHFDN-27.0(Rev.0,09/03)Tx+-+-Rcvpath+-+-Clean,open,logical1&0atlaunchfromtransmitterSmearededgesatendoflonginterconnect.Logical1&0canbehardtodistinguishatendoflonginterconnects;(thisisoftencalleda“closedeye”)Fast,sharp,edgesattransmitterlaunch第21页/共72页2023/4/2022高速串行总线－串扰

path+-+-Rcv+-+-Rcv+-+-Rcv+-+-RcvSerialdatacanbeasingledifferentialsignal…Tx+-Tx+-Tx+-Tx+-Tx+-+-+-+-Rcv…butgenerallytherearemultiple“lanes”ofserialdatarunningsidebyside;thesecanCROSSTALKwitheachother.第22页/共72页2023/4/2023高速串行总线－精度设计者要更加精确的掌控设计Tx+-path+-+-6.25Gb/satTxlaunchintobackplane6.25Gb/sat17in(43cm)ofbackplane6.25Gb/safter34in(86cm)ofbackplaneSmalldifferencesinlevelsbeingmeasured第23页/共72页2023/4/2024如何获得张开的眼图走线长度短走线并非始终能够满足.短走线意味低损耗.走线宽度宽走线可以降低趋肤效应.减小板材的介电常数即降低介电损耗(DielectricLoss),但将增加成本.信号预加重和均衡处理通过对跳变位预加重(Pre-Emphasis)处理补偿线路上因信号跳变产生的针对高频分量的损耗.其它接收端均衡处理等.第24页/共72页2023/4/2025眼图与BER究竟这个眼睛有多开?(…这却与你观察多久有关)?第25页/共72页2023/4/2026眼图与BERpdf1pdf2cdf20.5UI12ABC0UI1UIEyeopenforBER@1.0E-12-0.5UI1.5UIcdf1110眼睛睁开度vs误码率第26页/共72页2023/4/2027眼图与BER利用眼图分析抖动得到浴盆曲线(BathTub),从而进行误码率的估算。第27页/共72页2023/4/2028泰克提供的眼图测量方案从数据恢复时钟(CDR),眼图模板测试硬件CDR(PLL)软件CDR(PLL+其它)测量绘图抖动:趋势,频谱,

直方图,浴盆曲线第28页/共72页2023/4/2029硬件时钟恢复TDS6000B系列,TDS7704B和CSA7404B显示器锗化硅触发系统放大器/衰减器数据采集系统GoldenPLLFbd/166720dB/dec来自被选中的通道恢复时钟Ch2Ch3Ch4从1Mbit/s到

3.125Gbit/s的所有电接口和光接口速率独有的锗化硅触发系统第29页/共72页2023/4/2030硬件时钟恢复产生的眼图TDS6804B/P7380SMADSP增强功能XAUI超过3.125Gb/s眼图测量和统计第30页/共72页2023/4/2031新型测试方法

RT-Eye™方法生成眼图新兴标准要求新型工具TDSRT-Eye(选项RTE)基于泰克在软件领域的专家经验，创建了一个交钥匙式的一致性测试和分析解决方案第31页/共72页2023/4/2032新型测试方法

RT-Eye™方法生成眼图软件时钟恢复眼图全系列标准专用参数测量，包括幅度、定时和抖动多种格线图，进行补充数据分析标准专用模块作为插件提供用户可定制的波形模板、测量极限和报告功能，支持专有标准和新兴标准生成报告第32页/共72页2023/4/2033新型测试方法

RT-Eye™方法生成眼图低抖动本底噪声在TDS6604或TDS7704B上为700fsRMS单触发事件，而不是ET方法中的多触发事件支持不同的时钟恢复模型锁相环(PLL)相位内插重复取样(恒定时钟,连续位)数据相关分析把跳变位与非跳变位分开码型长度检测，进行抖动分析(Rj/Dj分离)恢复高达10Gb/s的时钟高达5Gb/s的眼图高达10Gb/s的抖动分析<0.1UI的抖动本底噪声第33页/共72页2023/4/2034RT-Eye眼图示例－TDS6804B和下一代标准2.5Gb/s5Gb/s6.25Gb/s第34页/共72页2023/4/2035

新型测试方法

RT-Eye™方法生成眼图－分析结果第35页/共72页2023/4/2036

新型测试方法

RT-Eye™方法生成眼图－抖动一致性测量TTX-EYE-MEDIAN-to-MAX-JITTERTTX-EYE-MEDIAN-MAX-JITTER第36页/共72页2023/4/2037

新型测试方法

RT-Eye™方法生成眼图－抖动一致性测量抖动眼图张开+总抖动=1UI第37页/共72页2023/4/2038采样示波器眼图生成Whenaclocksignalisusedtotriggertheequivalent-time8200scopethesampledDATAsignalsgenerallycreateEYEPATTERNS(betweenclocktriggersthesampledDATAcouldbeeitheralogical1or0)DatatriggervoltagetimePrecisionvariabledelayAclocktriggercanbeuser-suppliedorrecoveredfromthedatatotriggertheequivalenttimesamplerClockEyepatternsarethecommonresultofclock-triggeringinEquivalenttimesampling:vectorsarenotdrawnsinceadjacentsamplescanjumpfromlogical1to0frequentlyMasktest第38页/共72页2023/4/2039CSA8200with20GHz80E03采样示波器比较DRT示波器有更好的信号保真度Afast<15psrisingedgestimulusintoanETsystemandRTsystem;

AveragingOn.aberrationsarelisted<pre>,<post>step.DSPONtR10-90=22ps

aberrPkPk=0%,6.1%tR10-90=30.3ps

aberrPkPk=9.5%,7.2%TDS6154C,DSPOn.Averagingon第39页/共72页2023/4/2040CSA8200with20GHz80E03采样示波器比较DRT示波器有更好的信号保真度

Afast<15psrisingedgestimulusintoanETsystemandRTsystem.aberrationsarelisted<pre>,<post>step.TDS6154C,DSPOn.DSPONtR10-90=21ps

aberrPkPk=0%,5.5%tR10-90=22.5ps

aberrPkPk=10.4%,11.3%Averagingoff第40页/共72页2023/4/2041TDS8200ETScope(20GHz80E03)采样示波器与DRT示波器眼图对比TDS6154CRTw.DSPAnAdvantest12GbBERT(D3186)wasusedtodifferentiallydrivetwochannelsandalsosuppliedareferenceclock.LEFT:CHA-CHBonanTDS8200with80E0320GHzsamplerandan82A04PhaseReferencemoduleRIGHT:CH2-CH3onaTDS6154A(TDS6154C)realtimescope;eyegeneratedusingRT-Eye.第41页/共72页2023/4/2042TDS8200ET80E04采样示波器与DRT示波器眼图对比TDS6154CRTO,DSPOnSlowEyeDiagram(4GFC,cca.80psedges,600mVfullswing)(TDS6154comparisonisacomposition)MaskMargin=80%

MaskMargin=47%

Mask_MarginCSAisabout1.7xMask_MarginTDS第42页/共72页2023/4/2043应用对比选择TDS6154CDebugTriggeringProbingSignalAcquisitionSingleshotcapableNon-repetitivesignalsSuperiorAdvancedAnalysisJitterSerialDataApplicationsPower,etc.TDS8200SignalFidelityBandwidthNoiseAberrationsVertical&HorizontalresolutionTDR&TDRprobingFutureExtendibility(Modular)OpticalSupport第43页/共72页2023/4/2044YourTurnQuestions?Concerns?Suggestions?第44页/共72页ThankYouForAttending!MobilePhone:(045页/共72页2023/4/2046光通信基础知识介绍-性能参数光通信眼图比较关注的性能参数OMA(OpticModulationAmplitude)和ER(ExtinctionRatio)Q(Quality)OSNR(OpticSignaltoNoiseRatio)EyeOpening/EyeOpeningPenaltyBitErrorRateReciverSensitivity第46页/共72页2023/4/2047光通信基础知识介绍-性能参数逻辑1和逻辑0:光功率高的状态是逻辑1，反之则为逻辑0.光功率常用:dBm=10log10(Power(mW)/1(mW))OMA:OpticalModulationAmplitude逻辑1和逻辑0光功率差:OMA=P1-P0有时也定义成:ER:ExtinctionRatio,消光比第47页/共72页2023/4/2048光通信基础知识介绍-性能参数另外一个重要术语就是Q.理论上系统的误码率BER是完全由光纤的信噪(Signal-to-NoiseRatio)比决定的,也就是Q.一般主要在光纤放大器和接收端进行测量.第48页/共72页2023/4/2049光通信基础知识介绍-性能参数OSNR:OpticalSingal-to-NoiseRatio

对RZ编码传输系统,亦可定义如下:

和定义如右图示EOP:EyeOpeningPenalty测量系统的垂直方向的眼图张开度,公式定义如下:第49页/共72页2023/4/2050光通信基础知识介绍-性能参数BER:BitErrorRate

与Q和OSNR或光功率相关,是衡量传输系统性能的最直观的特征.当前光通信系统要求的BER一般在1E-9到1E-12之间.第50页/共72页2023/4/2051光通信基础知识介绍-SDH/SONETSONET:SynchronousOpticalNetwork.北美标准.SDH:SynchronousDigtialHierarchy.欧洲标准.中国采用SDH标准.第51页/共72页2023/4/2052光通信基础知识介绍-SDH/SONET第52页/共72页2023/4/2053光通信基础知识介绍-SDH/SONET-光速率光载波级别帧格式SDH级别帧格式速率OC-1STS-1--51.84Mbit/sOC-3STS-3SDH-1STM-1155.52Mbit/sOC-9STS-9--466.560Mbit/sOC-12STS-12SDH-4STM-4622.080Mbit/sOC-18STS-18-933.120Mbit/sOC-24STS-24SDH-8STM-81.244160Gbit/sOC-36STS-36SDH-12STM-121.866240Gbit/sOC-48STS-48SDH-16STM-162.488320Gbit/sOC-96STS-96SDH-32STM-324.976640Gbit/sOC-192STS-192SDH-64STM-649.953280Gbit/sOC-256STS-256--13.271040Gbit/sOC-384STS-384--19.906560Gbit/sOC-768STS-768--39.813120Gbit/s第53页/共72页2023/4/2054光通信基础知识介绍-SDH/SONET眼图模板RatesX1X2Y1STM-1OC-1&OC-3STM-4OC-9toOC-240.150.350.200.250.400.20

STM-1,STM-4

OC-1toOC-24NormalizedAmplitudeTime(UI)

X1X21-X21-X11+Y11-Y110.5Y10-Y1第54页/共72页2023/4/2055光通信基础知识介绍-SDH/SONET-TransmitPowerLevelsRate(Mb/s)ApplicationMeanLaunchPower(dBm)StandardSDHSDHSDHSONETSONETFC6222488248862224881063S-4.1S-16.1L-16.1SROC-12IR-1OC-48100-M5-SL-I-8-80-801.3MaximumMinimum-15-15-5-15-5-7GE12501000Base-SX0-10第55页/共72页2023/4/2056光通信基础知识介绍-SDH/SONET-MeasuringTransmitPowerOscilloscopewithOEConverterLimitedDynamicRange(0to-35dBm)Accuracyadequateforsometests(error6%,about±0.25dB)UsefulfortroubleshootingfunctionalityOpticalPowerMeterExtremelywideDynamicRange(+10dBmto-80dBm)Veryaccurate(error<3%,about±0.1dB)CalibratedformultiplewavelengthsUsefulfordevicecalibrationandaccuratelysettingpowerlevels第56页/共72页2023/4/2057光通信基础知识介绍-SDH/SONET-测试连接图PatternGeneratorOpticalSwitchOpticalPowerMeterO/EReferenceReceiverOscilloscopeApparatus:TransmitterEvaluationDataOutClockOutTriggerInSDUT第57页/共72页2023/4/2058光通信基础知识介绍-SDH/SONETExtinctionRatiosRate(Mb/s)ApplicationExtinctionRatio(dB)StandardSDHSDHSDHSONETSONETFC6222488248862224881063S-4.1S-16.1L-16.1SROC-12IR-1OC-48100-M5-SL-I8.28.2108.28.26GE12501000Base-SX9第58页/共72页2023/4/2059OpticalBandwidth(unfiltered)CSA7404BElectricalBandwidthMaximumReal-timeSampleRateTelecom/DatacomBitRates(max,filtered)OpticalSensitivityWavelengthRangeBasePrice(USD)2.4GHz4GHz20GS/s2.5Gb/s-17dBm700-1650nm$63,250(AP504CNPrice)光通信测量-CSA7000B第59页/共72页2023/4/2060光通信测量-CSA7000B主要产品有CSA7154B,CSA7404B.目前支持的最高速率为2.5Gb/s.第60页/共72页2023/4/2061光通信测量-CSA7000B-ORR第61页/共72页2023/4/2062光通信测量-CSA7000B-ORR四阶Bessel-ThomsonFilter频响图,CSA7000B内嵌四阶Bessel-Thomson数字滤波器.可以保证用户在不同速率之间平滑切换.而无需更换模块进行不同速率信号的测量.第62页/共72页2023/4/2063光通信测量-CSA7000B-ORR对NRZ编码光通信系统即通常的10Gb/s以下低速系统在接收端通常被设计成忽略高频上的细节,因为在高频上没有描述信号的重要参数.为了保持和真实接收端的一致性,内嵌的ORR带宽为0.75倍BitRate即1.5倍BitFrequency.对RZ编码而言,BitFrequency等于BitRate,则根本没有ORR标准.甚至无法确定应该在什么频率上进行滤波,虽然看起来象应该高于BitFrequency.这是由RZ编码的特点决定的.第63页/共72页2023/4/2064光通信测量-CSA7000B-Optical/ElectricalSystem(ORR)WaveformMemoryfO/EfCH1OpticalTXCSA7000FiberAcquisitionAmp/AttenuatorOtoEMicro-processorO/EtoCH1InterconnectCH1fORRDigitalFilteringApplicationFilterCoefficients第64页/共72页2023/4/2065光通信测量-CSA7000B-DigitalFilters-intheOpticalReferenceReceiverO/EAcquisitionOC-3FilterCoefficientsOC-12FilterCoefficientsOC-48FilterCoefficientsFC2125FilterCoefficientsFilterComputationSoftwareCalibrationKnownOpticalImpulseCSA7000OperationO/EAcquisitionOC-48FilterCoefficientsCSA7000asOC-48ORRWaveformDatabase第65页/共72页2023/4/2066光通信测量-CSA7000B-ORR–PerformanceandSimplicityIntegratedOpticalReferenceReceiver(ORR)Broad-wavelength,multimodeO/E

700to1650nm,calibratedat780,850,1310,1550nmLibraryofORRDigitalFilters4th-OrderBessel-ThompsonfiltersEasilydisabledtoprovidefull-bandwidthanalysisonopticalsignals.Eliminatestheneedforreconfiguringexternalaccessories,modulesorplug-insAllowseasyoptical/electricalConformanceTestingonawiderangeofCommstandardsupto2.5Gb/swithoneinstrumentInternalcalibrationensurestheaccuracyandrepeatabilityofresults=confidenceinmeasurementsanddesignmargins第66页/共72页2023/4/2067一个典型的SONET/SDH光纤传输系统收发单元示意图.

Thereceiver'soutputinterfaceprovidesregenerateddatainaserial orparallel(deserialized)bitstream,alongwiththerecoveredclock.光通信测量-CSA7000B-ClockRecovery在系统没有主时钟有效分布时需要采用ClockRecovery.系统主时钟可以在研究室或机房等有效分配或布置.分布式系统时钟(不同地点)可以用GPS接收机或时间-码产生机(time-codegenerators)进行同步(网络同步)–称为1层时钟(Stratum1clocks)(highestlevelaccuracy,synchronization).ClockRecovery提供相对精度低点,低级别的同步(抖动,PLL相关).第67页/共72页2023/4/2068光通信测量-CSA7000B-ClockRecoveryClockandDataRecovery(CDR)circuitfunctions:Firsttorecovertheclocksignal(CR)fromthereceiveddatastream(inputsignal).UsetheCRtoperformtimingandamplitude-leveldecisionsontheincomingsignal.Regeneratethedatastream(DR),withtimingandamplitudecharacteristics,synchronizedwith