眼圖及眼圖在信號測試中的運(yùn)用

眼圖及眼圖在串行信號測試中的運(yùn)用DM高級應(yīng)用工程師:黃騰

Email:thuang@

2024/6/171V1.0Confidential眼圖分析的原始驅(qū)動通訊技術(shù)發(fā)展的需要

SONET和SDH的在廣域傳輸中的廣泛應(yīng)用以及以太網(wǎng)技術(shù)的爆炸式應(yīng)用和發(fā)展電子系統(tǒng)從傳統(tǒng)的并行總線轉(zhuǎn)為串行總線HighlyScable,SerialInterface采用當(dāng)前許多最新的通訊行業(yè)成熟應(yīng)用的技術(shù):

PointtoPointInterconect,Switch-basedTechnology,PacketlizedProtocol2024/6/172V1.0Confidential高速串行總線和傳統(tǒng)并行總線對比2024/6/173V1.0Confidential高速串行總線－新興標(biāo)準(zhǔn)和數(shù)據(jù)速率FibreChannel4X4.25Gb/s4.25Gb/s(1X)FBDIMM4.8Gb/s

>500Gb/s

(14lanesx8channels)2024/6/174V1.0Confidential眼圖定義2024/6/175V1.0Confidential一般信號與眼圖的區(qū)別2024/6/176V1.0Confidential眼圖特征定義

2024/6/177V1.0Confidential眼圖特征定義2024/6/178V1.0Confidential眼圖形成示意2024/6/179V1.0Confidential眼圖在示波器上的形成2024/6/1710V1.0Confidential眼圖的CLK采樣示波器的CLK通常可能是用戶提供的時鐘,恢復(fù)時鐘,或者與數(shù)據(jù)信號本身同步的碼同步信號.實(shí)時示波器通過一次觸發(fā)完成所有數(shù)據(jù)的采樣,不需附加的同步信號和觸發(fā)信號.通常通過軟件PLL方法恢復(fù)時鐘.TektronixRT-Eye軟件即使用此方法.TDS8200ETScope(20GHz80E03)TDS6154CRTw.DSP2024/6/1711V1.0Confidential眼圖與CLK－時鐘速率提高,眼圖質(zhì)量下降125MCLK250MCLK500MCLK2024/6/1712V1.0Confidential示波器上的眼圖提供串行總線數(shù)據(jù)的豐富信息:通過比較發(fā)送端和接收端的眼圖質(zhì)量可以分析出信號傳輸?shù)膯栴}

眼高,眼底,眼寬上升時間下降時間模板測試2024/6/1713V1.0Confidential眼圖與系統(tǒng)速率水平時域上關(guān)聯(lián)因素

Transition(rise)timeAperturetimeTiminguncertainty,skewandjitter垂直域幅度損耗和噪聲Unimparedbitedge2024/6/1714V1.0Confidential眼圖和傳輸質(zhì)量LargereyeopeningmeansgreatertolerancetoamplitudeandtimingvariationsLargereyeopeningtranslatestosimplersystemdesignandbetterreliabilityWidertransitionregionindicatesgreaterjitterandhigherbiterrorrateBesterrorrateobtainedwhendecisionpointisnearcenteroftheeye2024/6/1715V1.0ConfidentialPValuesPTopmean

,themeanvalueofPTopPTopsigma,thestandarddevofPTopPBasemean,meanvaluewithinaperturePBasesigma,stddevofPBaseinaperturePcrossmean,verticalmeanofcrossingpt.TValuesTcrossmean,horizmeanofcrossingpt.Tcrosssigma,horizstddevofcrossingpt.Tcrosspk-pk,horizpk-pkofcrossingpt.TheEyeAperturedefaultstothecenter20%oftheintervalfromTCross1toTCross2butissettablefrom0to100%眼圖測量特征量TCross1TCross2PCross1PCross2EyeAperturePBasePTop2024/6/1716V1.0Confidential

JitterRMS=TCross1sigmaJitterPk-Pk=TCross1pk-pk

ExtinctionRatio=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眼圖測量特征量TCross1TCross2PCross1PCross2EyeAperturePBasePTop2024/6/1717V1.0Confidential眼圖的測量近端遠(yuǎn)端采樣點(diǎn)

串?dāng)_

隨機(jī)抖動

確定性抖動碼間干擾(ISI)占空比失真(DCD)正弦抖動(SJ)無關(guān)聯(lián)的

幅度損耗2024/6/1718V1.0Confidential串行總線:

Basic

blocksTransmittersInterconnects(paths)ReceiversTx+-path+-+-path+-+-path+-+-+-RcvDifferentialTransmitterDual-coax

differentialcableTwisted-pairdifferentialcableCoupled-pairtracesoncircuitboard(backplanes)DifferentialReceiver2024/6/1719V1.0Confidential高速串行總線－信號線上不僅包含數(shù)據(jù)信息還包含時鐘信息pathTx+-+-+-+-RcvDifferentialserialdataissentwithoutanyclocksignalacrosstheinterconnecttothereceiverCDRDATADATACLOCKAclockis“recovered”fromtheincomingdataatthereceiverthroughaclockanddatarecoverycircuit(CDR).2024/6/1720V1.0Confidential高速串行總線－數(shù)據(jù)傳輸過程中干擾因素增多path+-+-path+-+-Tx+-path+-+-+-RcvTx+-path+-+-+-Rcvpath+-+-Tx+-path+-+-+-Rcvpath+-+-Transitionpointsofteninvolvecombinationsofsolderjoints,circuitboardvias,andconnectors:theseallcanhavesubstantialeffectonthetotallinkperformance.2024/6/1721V1.0Confidential高速串行總線－損耗速率越高互連距離越長,損耗越大ReferenceMaximNoteHFDN-27.0(Rev.0,09/03)Tx+-+-Rcvpath+-+-Clean,open,logical1&0atlaunchfromtransmitterSmearededgesatendoflonginterconnect.Logical1&0canbehardtodistinguishatendoflonginterconnects;(thisisoftencalleda“closedeye”)Fast,sharp,edgesattransmitterlaunch2024/6/1722V1.0Confidential高速串行總線－串?dāng)_

path+-+-Rcv+-+-Rcv+-+-Rcv+-+-RcvSerialdatacanbeasingledifferentialsignal…Tx+-Tx+-Tx+-Tx+-Tx+-+-+-+-Rcv…butgenerallytherearemultiple“l(fā)anes”ofserialdatarunningsidebyside;thesecanCROSSTALKwitheachother.2024/6/1723V1.0Confidential高速串行總線－精度

設(shè)計(jì)者要更加精確的掌控設(shè)計(jì)Tx+-path+-+-6.25Gb/satTxlaunchintobackplane6.25Gb/sat17in(43cm)ofbackplane6.25Gb/safter34in(86cm)ofbackplaneSmalldifferencesinlevelsbeingmeasured2024/6/1724V1.0Confidential如何獲得張開的眼圖走線長度短走線并非始終能夠滿足.短走線意味低損耗.走線寬度寬走線可以降低趨膚效應(yīng).減小板材的介電常數(shù)即降低介電損耗(DielectricLoss),但將增加成本.信號預(yù)加重和均衡處理通過對跳變位預(yù)加重(Pre-Emphasis)處理補(bǔ)償線路上因信號跳變產(chǎn)生的針對高頻分量的損耗.

其它接收端均衡處理等.2024/6/1725V1.0Confidential眼圖與BER究竟這個眼睛有多開?(…這卻與你觀察多久有關(guān))?2024/6/1726V1.0Confidential眼圖與BERpdf

1pdf

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20.5UI12ABC0UI1UIEyeopenforBER@1.0E-12-0.5UI1.5UIcdf

1110眼睛睜開度

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誤碼率2024/6/1727V1.0Confidential眼圖與BER利用眼圖分析抖動得到浴盆曲線(BathTub),從而進(jìn)行誤碼率的估算。2024/6/1728V1.0Confidential泰克提供的眼圖測量方案從數(shù)據(jù)恢復(fù)時鐘(CDR),眼圖模板測試硬件CDR(PLL)軟件CDR(PLL+其它)測量繪圖抖動:趨勢,頻譜,

直方圖,浴盆曲線2024/6/1729V1.0Confidential硬件時鐘恢復(fù)TDS6000B系列,

TDS7704B和CSA7404B顯示器鍺化硅觸發(fā)

系統(tǒng)放大器/衰減器數(shù)據(jù)采集系統(tǒng)GoldenPLLFbd/166720dB/dec來自被

選中的通道恢復(fù)時鐘Ch2Ch3Ch4從1Mbit/s到

3.125Gbit/s的所有電接口和光接口速率獨(dú)有的

鍺化硅觸發(fā)系統(tǒng)2024/6/1730V1.0Confidential硬件時鐘恢復(fù)產(chǎn)生的眼圖TDS6804B/P7380SMADSP增強(qiáng)功能XAUI超過3.125Gb/s眼圖測量和統(tǒng)計(jì)2024/6/1731V1.0Confidential新型測試方法

RT-Eye?方法生成眼圖新興標(biāo)準(zhǔn)要求新型工具TDSRT-Eye(選項(xiàng)RTE)基于泰克在軟件領(lǐng)域的專家經(jīng)驗(yàn)，創(chuàng)建了一個交鑰匙式的一致性測試和分析解決方案2024/6/1732V1.0Confidential新型測試方法

RT-Eye?方法生成眼圖軟件時鐘恢復(fù)眼圖全系列標(biāo)準(zhǔn)專用參數(shù)測量，包括幅度、定時和抖動多種格線圖，進(jìn)行補(bǔ)充數(shù)據(jù)分析標(biāo)準(zhǔn)專用模塊作為插件提供用戶可定制的波形模板、測量極限和報(bào)告功能，支持專有標(biāo)準(zhǔn)和新興標(biāo)準(zhǔn)生成報(bào)告2024/6/1733V1.0Confidential新型測試方法

RT-Eye?方法生成眼圖低抖動本底噪聲在TDS6604或TDS7704B上為700fsRMS單觸發(fā)事件，而不是ET方法中的多觸發(fā)事件支持不同的時鐘恢復(fù)模型鎖相環(huán)(PLL)相位內(nèi)插重復(fù)取樣(恒定時鐘,連續(xù)位)數(shù)據(jù)相關(guān)分析把跳變位與非跳變位分開碼型長度檢測，進(jìn)行抖動分析(Rj/Dj分離)恢復(fù)高達(dá)10Gb/s的時鐘高達(dá)5Gb/s的眼圖高達(dá)10Gb/s的抖動分析<0.1UI的抖動本底噪聲2024/6/1734V1.0ConfidentialRT-Eye眼圖示例－TDS6804B和下一代標(biāo)準(zhǔn)2.5Gb/s5Gb/s6.25Gb/s2024/6/1735V1.0Confidential

新型測試方法

RT-Eye?方法生成眼圖－分析結(jié)果2024/6/1736V1.0Confidential

新型測試方法

RT-Eye?方法生成眼圖－抖動一致性測量TTX-EYE-MEDIAN-to-MAX-JITTERTTX-EYE-MEDIAN-MAX-JITTER2024/6/1737V1.0Confidential

新型測試方法

RT-Eye?方法生成眼圖－抖動一致性測量抖動眼圖張開+總抖動=1UI2024/6/1738V1.0Confidential采樣示波器眼圖生成Whenaclocksignalisusedtotriggertheequivalent-time8200scopethesampledDATAsignalsgenerallycreateEYEPATTERNS(betweenclocktriggersthesampledDATAcouldbeeitheralogical1or0)DatatriggervoltagetimePrecisionvariabledelayAclocktriggercanbeuser-suppliedorrecoveredfromthedatatotriggertheequivalenttimesamplerClockEyepatternsarethecommonresultofclock-triggeringinEquivalenttimesampling:vectorsarenotdrawnsinceadjacentsamplescanjumpfromlogical1to0frequentlyMasktest2024/6/1739V1.0ConfidentialCSA8200with20GHz80E03采樣示波器比較DRT示波器有更好的信號保真度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.Averagingon2024/6/1740V1.0ConfidentialCSA8200with20GHz80E03采樣示波器比較DRT示波器有更好的信號保真度

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

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

aberrPkPk=10.4%,11.3%Averagingoff2024/6/1741V1.0ConfidentialTDS8200ETScope(20GHz80E03)采樣示波器與DRT示波器眼圖對比TDS6154CRTw.DSPAnAdvantest12GbBERT(D3186)wasusedtodifferentiallydrivetwochannelsandalsosuppliedareferenceclock.LEFT:CHA-CHBonanTDS8200with80E0320GHzsamplerandan82A04PhaseReferencemoduleRIGHT:CH2-CH3onaTDS6154A(TDS6154C)realtimescope;eyegeneratedusingRT-Eye.2024/6/1742V1.0ConfidentialTDS8200ET80E04采樣示波器與DRT示波器眼圖對比TDS6154CRTO,DSPOnSlowEyeDiagram(4GFC,cca.80psedges,600mVfullswing)(TDS6154comparisonisacomposition)MaskMargin=80%

MaskMargin=47%

Mask_MarginCSAisabout1.7xMask_MarginTDS2024/6/1743V1.0Confidential應(yīng)用對比選擇TDS6154CDebugTriggeringProbingSignalAcquisitionSingleshotcapableNon-repetitivesignalsSuperiorAdvancedAnalysisJitterSerialDataApplicationsPower,etc.TDS8200SignalFidelityBandwidthNoiseAberrationsVertical&HorizontalresolutionTDR&TDRprobingFutureExtendibility(Modular)OpticalSupport2024/6/1744V1.0ConfidentialYourTurnQuestions?Concerns?Suggestions?2024/6/1745V1.0ConfidentialThankYouForAttending!MobilePhone:(0)137616846202024/6/1746V1.0Confidential光通信基礎(chǔ)知識介紹-性能參數(shù)光通信眼圖比較關(guān)注的性能參數(shù)

OMA(OpticModulationAmplitude)和ER(ExtinctionRatio)Q(Quality)OSNR(OpticSignaltoNoiseRatio)EyeOpening/EyeOpeningPenaltyBitErrorRateReciverSensitivity2024/6/1747V1.0Confidential光通信基礎(chǔ)知識介紹-性能參數(shù)邏輯1和邏輯0:

光功率高的狀態(tài)是邏輯1，反之則為邏輯0.

光功率常用:dBm=10log10(Power(mW)/1(mW))OMA:OpticalModulationAmplitude

邏輯1和邏輯0光功率差:

OMA=P1-P0

有時也定義成:ER:ExtinctionRatio,消光比2024/6/1748V1.0Confidential光通信基礎(chǔ)知識介紹-性能參數(shù)另外一個重要術(shù)語就是Q.理論上系統(tǒng)的誤碼率BER是完全由光纖的信噪(Signal-to-NoiseRatio)比決定的,也就是Q.一般主要在光纖放大器和接收端進(jìn)行測量.2024/6/1749V1.0Confidential光通信基礎(chǔ)知識介紹-性能參數(shù)OSNR:OpticalSingal-to-NoiseRatio

對RZ編碼傳輸系統(tǒng),亦可定義如下:

和定義如右圖示EOP:EyeOpeningPenalty

測量系統(tǒng)的垂直方向的眼圖張開度,公式定義如下:2024/6/1750V1.0Confidential光通信基礎(chǔ)知識介紹-性能參數(shù)BER:BitErrorRate

與Q和OSNR或光功率相關(guān),是衡量傳輸系統(tǒng)性能的最直觀的特征.

當(dāng)前光通信系統(tǒng)要求的BER一般在1E-9到1E-12之間.2024/6/1751V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONETSONET:SynchronousOpticalNetwork.北美標(biāo)準(zhǔn).SDH:SynchronousDigtialHierarchy.歐洲標(biāo)準(zhǔn).中國采用SDH標(biāo)準(zhǔn).2024/6/1752V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONET2024/6/1753V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONET-光速率光載波級別幀格式SDH級別幀格式速率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/s2024/6/1754V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONET眼圖模板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-Y12024/6/1755V1.0Confidential光通信基礎(chǔ)知識介紹-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-SX0-102024/6/1756V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONET-MeasuringTransmitPowerOscilloscopewithOEConverterLimitedDynamicRange(0to-35dBm)Accuracyadequateforsometests(error6%,about±0.25dB)UsefulfortroubleshootingfunctionalityOpticalPowerMeterExtremelywideDynamicRange(+10dBmto-80dBm)Veryaccurate(error<3%,about±0.1dB)CalibratedformultiplewavelengthsUsefulfordevicecalibrationandaccuratelysettingpowerlevels2024/6/1757V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONET-測試連接圖PatternGeneratorOpticalSwitchOpticalPowerMeterO/EReferenceReceiverOscilloscopeApparatus:TransmitterEvaluationDataOutClockOutTriggerInSDUT2024/6/1758V1.0Confidential光通信基礎(chǔ)知識介紹-SDH/SONETExtinctionRatiosRate(Mb/s)ApplicationExtinctionRatio(dB)StandardSDHSDHSDHSONETSONETFC6222488248862224881063S-4.1S-16.1L-16.1SROC-12IR-1OC-48100-M5-SL-I8.28.2108.28.26GE12501000Base-SX92024/6/1759V1.0ConfidentialOpticalBandwidth(unfiltered)CSA7404BElectricalBandwidthMaximumReal-timeSampleRateTelecom/DatacomBitRates(max,filtered)OpticalSensitivityWavelengthRangeBasePrice(USD)2.4GHz4GHz20GS/s2.5Gb/s-17dBm700-1650nm$63,250(AP504CNPrice)光通信測量-CSA7000B2024/6/1760V1.0Confidential光通信測量-CSA7000B主要產(chǎn)品有CSA7154B,CSA7404B.目前支持的最高速率為2.5Gb/s.2024/6/1761V1.0Confidential光通信測量-CSA7000B-ORR2024/6/1762V1.0Confidential光通信測量-CSA7000B-ORR四階Bessel-ThomsonFilter頻響圖,CSA7000B內(nèi)嵌四階Bessel-Thomson數(shù)字濾波器.可以保證用戶在不同速率之間平滑切換.而無需更換模塊進(jìn)行不同速率信號的測量.2024/6/1763V1.0Confidential光通信測量-CSA7000B-ORR對NRZ編碼光通信系統(tǒng)即通常的10Gb/s以下低速系統(tǒng)在接收端通常被設(shè)計(jì)成忽略高頻上的細(xì)節(jié),因?yàn)樵诟哳l上沒有描述信號的重要參數(shù).為了保持和真實(shí)接收端的一致性,內(nèi)嵌的ORR帶寬為0.75倍BitRate即1.5倍BitFrequency.對RZ編碼而言,BitFrequency等于BitRate,則根本沒有ORR標(biāo)準(zhǔn).甚至無法確定應(yīng)該在什么頻率上進(jìn)行濾波,雖然看起來象應(yīng)該高于BitFrequency.這是由RZ編碼的特點(diǎn)決定的.2024/6/1764V1.0Confidential光通信測量-CSA7000B-Optical/ElectricalSystem(ORR)WaveformMemoryfO/EfCH1OpticalTXCSA7000FiberAcquisitionAmp/AttenuatorOtoEMicro-processorO/EtoCH1InterconnectCH1fORRDigitalFilteringApplicationFilterCoefficients2024/6/1765V1.0Confidential光通信測量-CSA7000B-DigitalFilters-intheOpticalReferenceReceiverO/EAcquisitionOC-3FilterCoefficientsOC-12FilterCoefficientsOC-48FilterCoefficientsFC2125FilterCoefficientsFilterComputationSoftwareCalibrationKnownOpticalImpulseCSA7000OperationO/EAcquisitionOC-48FilterCoefficientsCSA7000asOC-48ORRWaveformDatabase2024/6/1766V1.0Confidential光通信測量-CSA7000B-ORR–PerformanceandSimplicityIntegratedOpticalReferenceReceiver(ORR)Broad-wavelength,multimodeO/E

700to1650nm,calibratedat780,850,1310,1550nmLibraryofORRDigitalFilters4th-OrderBessel-ThompsonfiltersEasilydisabledtoprovidefull-bandwidthanalysisonopticalsignals.Eliminatestheneedforreconfiguringexternalaccessories,modulesorplug-insAllowseasyoptical/electricalConformanceTestingonawiderangeofCommstandardsupto2.5Gb/swithoneinstrumentInternalcalibrationensurestheaccuracyandrepeatabilityofresults=confidenceinmeasurementsanddesignmargins2024/6/1767V1.0Confidential一個典型的SONET/SDH光纖傳輸系統(tǒng)收發(fā)單元示意圖.

Thereceiver'soutputinterfaceprovidesregenerateddatainaserial orparallel(deserialized)bitstream,alongwiththerecoveredclock.光通信測量-CSA7000B-ClockRecovery在系統(tǒng)沒有主時鐘有效分布時需要采用Clock

Recovery.系統(tǒng)主時鐘可以在研究室或機(jī)房等有效分配或布置.分布式系統(tǒng)時鐘(不同地點(diǎn))可以用GPS接收機(jī)或時間-碼產(chǎn)生機(jī)(time-codegenerators)進(jìn)行同步(網(wǎng)絡(luò)同步)

–稱為1層時鐘(Stratum1clocks)(highestlevelaccuracy,synchronization).ClockRecovery提供相對精度低點(diǎn),低級別的同步(抖動,

PLL

相關(guān)).2024/6/1768V1.0Confidential光通信測量-CSA7000B-ClockRecoveryClockandDataRecovery(CDR)circuitfunctions:Firsttorecovertheclocksignal(CR)fromthereceiveddatastream(inputsignal).UsetheCRtoperformtimingandamplitude-leveldecisions