眼图及眼图在信号测试中的运用.ppt

眼图及眼图在串行信号测试中的运用DMDM高级应用工程师高级应用工程师: :黄腾黄腾Email:thuang@Email:thuang@眼图分析的原始驱动通讯技术发展的需要 SONET和SDH的在广域传输中的广泛应用以及以太网技术的爆炸式应用和发展电子系统从传统的并行总线转为串行总线 Highly Scable,Serial Interface 采用当前许多最新的通讯行业成熟应用的技术: Point to Point Interconect,Switch-based Technology, Packetlized Protocol2024/8/192V1.0 Confidential高速串行总线和传统并行总线对比2024/8/193V1.0 Confidential高速串行总线－新兴标准和数据速率FibreChannel 4X 4.25 Gb/s 4.25Gb/s (1X)FBDIMM 4.8 Gb/s >500 Gb/s (14 lanes x 8 channels)2024/8/194V1.0 Confidential眼图定义2024/8/195V1.0 Confidential一般信号与眼图的区别2024/8/196V1.0 Confidential眼图特征定义 2024/8/197V1.0 Confidential眼图特征定义2024/8/198V1.0 Confidential眼图形成示意2024/8/199V1.0 Confidential眼图在示波器上的形成2024/8/1910V1.0 Confidential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.Tektronix RT-Eye软件即使用此方法.TDS8200 ET Scope (20GHz 80E03)TDS6154C RT w. DSP2024/8/1911V1.0 Confidential眼图与CLK－时钟速率提高,眼图质量下降125M CLK250M CLK500M CLK2024/8/1912V1.0 Confidential示波器上的眼示波器上的眼图图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2024/8/1913V1.0 Confidential眼图与系统速率水平时域上关联因素 Transition (rise) time Aperture timeTiming uncertainty, skew and jitter垂直域 幅度损耗和噪声Unimpared bit edge2024/8/1914V1.0 Confidential眼图和传输质量Larger eye opening means greater tolerance to amplitude and timing variationsLarger eye opening translates to simpler system design and better reliabilityWider transition region indicates greater jitter and higher bit error rateBest error rate obtained when decision point is near center of the eye2024/8/1915V1.0 ConfidentialP ValuesPTopmean , the mean value of PTopPTopsigma , the standard dev of PTopPBasemean , mean value within aperturePBasesigma , std dev of PBase in aperturePcrossmean , vertical mean of crossing pt.T ValuesTcrossmean , horiz mean of crossing pt.Tcrosssigma , horiz std dev of crossing pt.Tcrosspk-pk , horiz pk-pk of crossing pt.The Eye Aperture defaults to the center 20% of the interval from TCross1 to TCross2 but is settable from 0 to 100%眼图测量特征量TCross1TCross2PCross1PCross2Eye AperturePBasePTop2024/8/1916V1.0 Confidential4 Jitter RMS = TCross1sigma4 Jitter Pk-Pk = TCross1pk-pk4 Extinction Ratio = PTopmean /PBasemean (ER also in dB and %)4 Quality Factor = (PTopmean-PBasemean)/(PTopsigma+PBasesigma)4 Eye Height = (PTopmean-3*PTopsigma)-(PBasemean+3*PBasesigma)4 Eye Width = (TCross2mean-3*TCross2sigma)-(TCross1mean+3*TCross1sigma)4 Crossing Percent, Duty Cycle Distortion, Noisepk-pk, NoiseRMS, SNR眼图测量特征量眼图测量特征量TCross1TCross2PCross1PCross2Eye AperturePBasePTop2024/8/1917V1.0 Confidential眼图的测量近端近端远端远端采样点 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2024/8/1918V1.0 Confidential串行串行总线总线:￿Basicasic￿ ￿blocksblocksTransmittersInterconnects (paths)ReceiversTx+-path+-+-path+-+-path+-+-+-RcvDifferential TransmitterDual-coax differential cableTwisted-pair differential cableCoupled-pair traces on circuit board (backplanes)Differential Receiver2024/8/1919V1.0 Confidential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+-+-+-+-RcvDifferential serial data is sent without any clock signal across the interconnect to the receiverCDRDATADATACLOCKA clock is “recovered” from the incoming data at the receiver through a clock and data recovery circuit (CDR).2024/8/1920V1.0 Confidential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+-+-Transition points often involve combinations of solder joints, circuit board vias, and connectors: these all can have substantial effect on the total link performance.2024/8/1921V1.0 Confidential高速串行总线－损耗￿速率越高互连距离越长,损耗越大Reference Maxim Note HFDN-27.0 (Rev. 0, 09/03)Tx+-+-Rcvpath+-+-Clean, open, logical 1 & 0 at launch from transmitterSmeared edges at end of long interconnect.Logical 1 & 0 can be hard to distinguish at end of long interconnects; (this is often called a “closed eye”)Fast, sharp, edges at transmitter launch2024/8/1922V1.0 Confidential高速串行总线－串扰 path+-+-Rcv+-+-Rcv+-+-Rcv+-+-RcvSerial data can be a single differential signal…Tx+-Tx+-Tx+-Tx+-Tx+-+-+-+-Rcv…but generally there are multiple “lanes” of serial data running side by side; these can CROSSTALK with each other.2024/8/1923V1.0 Confidential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/s at Tx launch into backplane6.25Gb/s at 17in (43cm) of backplane6.25Gb/s after 34in (86cm) of backplaneSmall differences in levels being measured2024/8/1924V1.0 Confidential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(Dielectric Loss),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.2024/8/1925V1.0 Confidential眼图与BER8究竟这个眼睛有多开究竟这个眼睛有多开? (…这却与你观察多久有关这却与你观察多久有关)?2024/8/1926V1.0 Confidential眼图与BERpdf 1pdf 2cdf 20.5UI12ABC0UI1UIEye open for BER @ 1.0E-12- 0.5UI1.5UIcdf 1110眼睛眼睛睁开度睁开度 vs 误误码率码率2024/8/1927V1.0 Confidential眼图与BER利用眼图分析抖动得到浴盆曲线(Bath Tub),从而进行误码率的估算。

2024/8/1928V1.0 Confidential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2024/8/1929V1.0 Confidential硬件时钟恢复TDS6000B 系列系列, TDS7704B 和和 CSA7404B 显示器显示器锗化硅触发锗化硅触发 系统系统放大器放大器/衰减器衰减器数据数据采集采集系统系统Golden PLLFbd/166720 dB/dec来自被来自被 选中的选中的通道通道恢复恢复时钟时钟Ch2 Ch3Ch4从1Mbit/s到 3.125Gbit/s的所有电接口和光接口速率独有的 锗化硅触发锗化硅触发系统系统2024/8/1930V1.0 Confidential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2024/8/1931V1.0 Confidential新型新型测试方法方法RT-Eye™方法生成眼图新兴标准要求新型工具TDS RT-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2024/8/1932V1.0 Confidential新型新型测试方法方法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2024/8/1933V1.0 Confidential新型新型测试方法方法RT-Eye™方法生成眼图低抖动本底噪声–在TDS6604 或 TDS7704B上为700 fs RMS–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<0.1 UI的抖动本底噪声2024/8/1934V1.0 ConfidentialRT-Eye眼图示例－TDS6804B和下一代标准2.5Gb/s5Gb/s6.25Gb/s2024/8/1935V1.0 Confidential新型新型测试方法方法RT-Eye™方法生成眼图－分析结果2024/8/1936V1.0 Confidential新型新型测试方法方法RT-Eye™方法生成眼图－抖动一致性测量T TX-EYE-MEDIAN-to-MAX-JITTERTTX-EYE-MEDIAN-MAX-JITTER2024/8/1937V1.0 Confidential新型新型测试方法方法RT-Eye™方法生成眼图－抖动一致性测量抖动眼图张开 + 总抖动 = 1UI2024/8/1938V1.0 Confidential采样示波器眼图生成When a clock signal is used to trigger the equivalent-time 8200 scope the sampled DATA signals generally create EYE PATTERNS (between clock triggers the sampled DATA could be either a logical 1 or 0)DatavoltagetimePrecision variable delayA clock trigger can be user-supplied or recovered from the data to trigger the equivalent time samplerClockEye patterns are the common result of clock-triggering in Equivalent time sampling: vectors are not drawn since adjacent samples can jump from logical 1 to 0 frequentlyMask test2024/8/1939V1.0 ConfidentialCSA8200 with 20GHz 80E03采样示波器比较DRT示波器有更好的信号保真度A fast <15ps rising edge stimulus into an ET system and RT system;Averaging On. aberrations are listed

, step.DSP ONtR 10-90=22psaberrPkPk=0%, 6.1%tR 10-90=30.3psaberrPkPk=9.5%, 7.2%TDS6154C, DSP On.Averaging on2024/8/1940V1.0  ConfidentialCSA8200 with 20GHz 80E03采样示波器比较DRT示波器有更好的信号保真度 A fast <15ps rising edge stimulus into an ET system and RT system. aberrations are listed 
, step.TDS6154C, DSP On.DSP ONtR 10-90=21psaberrPkPk=0%, 5.5%tR 10-90=22.5psaberrPkPk=10.4%, 11.3%Averaging off2024/8/1941V1.0  ConfidentialTDS8200 ET Scope (20GHz 80E03)采样示波器与DRT示波器眼图对比TDS6154C RT w. DSPAn Advantest 12Gb BERT (D3186) was used to differentially drive two channels and also supplied a reference clock.LEFT:CHA-CHB on an TDS8200 with 80E03 20GHz sampler and an 82A04 Phase Reference moduleRIGHT:CH2-CH3 on a TDS6154A (TDS6154C) realtime scope; eye generated using RT-Eye.2024/8/1942V1.0  ConfidentialTDS8200 ET 80E04采样示波器与DRT示波器眼图对比TDS6154C RTO, DSP OnSlow Eye Diagram (4GFC, cca. 80ps edges, 600mV full swing)(TDS6154 comparison is a composition)Mask Margin=80%Mask Margin=47%Mask_MarginCSA is about 1.7x Mask_MarginTDS2024/8/1943V1.0  Confidential应用对比选择TDS6154C–DebugTriggeringProbing–Signal AcquisitionSingle shot capableNon-repetitive signals–Superior Advanced AnalysisJitterSerial Data ApplicationsPower, etc.TDS8200–Signal FidelityBandwidthNoiseAberrationsVertical & Horizontal resolution–TDR & TDR probing–Future Extendibility (Modular)–Optical Support2024/8/1944V1.0  ConfidentialYour TurnQuestions?Concerns?Suggestions?2024/8/1945V1.0  ConfidentialThank You For Attending!Mobile Phone:(0)13761684620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(Optic Modulation Amplitude)和ER(Extinction Ratio)          Q(Quality)          OSNR(Optic Signal to Noise Ratio)          Eye Opening/Eye Opening Penalty          Bit Error Rate          Reciver Sensitivity2024/8/1947V1.0  Confidential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:Optical Modulation Amplitude            逻辑1和逻辑0光功率差:            OMA=P1-P0            有时也定义成:ER:Extinction Ratio,消光比2024/8/1948V1.0  Confidential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-Noise Ratio)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.2024/8/1949V1.0  Confidential光通信基础知识介绍-性能参数OSNR:Optical Singal-to-Noise Ratio                                 对RZ编码传输系统,亦可定义如下:                                                                        和        定义如右图示EOP:Eye Opening Penalty      测量系统的垂直方向的眼图      张开度,公式定义如下:2024/8/1950V1.0  Confidential光通信基础知识介绍-性能参数BER:Bit Error Rate             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.2024/8/1951V1.0  Confidential光通信基础知识介绍-SDH/SONETSONET:Synchronous Optical Network.北美标准.SDH:Synchronous Digtial Hierarchy.欧洲标准.中国采用SDH标准.2024/8/1952V1.0  Confidential光通信基础知识介绍-SDH/SONET2024/8/1953V1.0  Confidential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/s OC-3STS-3SDH-1STM-1155.52Mbit/s OC-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/s2024/8/1954V1.0  Confidential光通信基础知识介绍-SDH/SONET 眼图模板RatesX1X2Y1STM-1OC-1 & OC-3STM-4OC-9 to OC-240.150.350.200.250.400.20 STM-1,  STM-4  OC-1 to OC-24NormalizedAmplitudeTime (UI) X1X21-X21-X11+Y11-Y110.5Y10-Y12024/8/1955V1.0  Confidential光通信基础知识介绍-SDH/SONET-Transmit Power LevelsRate (Mb/s)ApplicationMean Launch Power (dBm)StandardSDHSDHSDHSONETSONETFC6222488248862224881063S-4.1S-16.1L-16.1SR OC-12IR-1 OC-48100-M5-SL-I-8-80-801.3MaximumMinimum-15-15-5-15-5-7GE12501000Base-SX0-102024/8/1956V1.0  Confidential光通信基础知识介绍-SDH/SONET-Measuring Transmit PowerOscilloscope with OE Converter–Limited Dynamic Range (0 to -35 dBm)–Accuracy adequate for some tests (error 6%, about ± 0.25dB)–Useful for troubleshooting functionalityOptical Power Meter–Extremely wide Dynamic Range (+10 dBm to -80 dBm)–Very accurate (error < 3%, about ± 0.1 dB)–Calibrated for multiple wavelengths–Useful for device calibration and accurately setting power levels2024/8/1957V1.0  Confidential光通信基础知识介绍-SDH/SONET-测试连接图Pattern GeneratorOptical SwitchOptical Power MeterO/EReference Receiver OscilloscopeApparatus:  Transmitter EvaluationData OutClock OutTrigger InSDUT2024/8/1958V1.0  Confidential光通信基础知识介绍-SDH/SONET Extinction RatiosRate (Mb/s)ApplicationExtinction Ratio (dB)StandardSDHSDHSDHSONETSONETFC6222488248862224881063S-4.1S-16.1L-16.1SR OC-12IR-1 OC-48100-M5-SL-I8.28.2108.28.26GE12501000Base-SX92024/8/1959V1.0  ConfidentialOptical Bandwidth (unfiltered)CSA7404BElectrical BandwidthMaximum Real-time Sample RateTelecom/Datacom Bit Rates (max, filtered)Optical SensitivityWavelength RangeBase Price (USD)2.4 GHz4 GHz20 GS/s2.5 Gb/s-17 dBm700-1650 nm$63,250(AP504 CN Price)光通信测量-CSA7000B2024/8/1960V1.0  Confidential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.2024/8/1961V1.0  Confidential光通信测量-CSA7000B-ORR2024/8/1962V1.0  Confidential光通信测量-CSA7000B-ORR四阶Bessel-Thomson Filter 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.2024/8/1963V1.0  Confidential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Bit Rate即1.5倍Bit Frequency.对RZ编码而言,Bit Frequency等于Bit Rate,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Bit Frequency.这是由RZ编码的特点决定的.2024/8/1964V1.0  Confidential光通信测量-CSA7000B-Optical/Electrical System (ORR)WaveformMemoryf O/Ef CH 1Optical TXCSA7000 FiberAcquisitionAmp/AttenuatorO to EMicro-processorO/E to CH1 InterconnectCH 1f ORRDigital Filtering ApplicationFilterCoefficients2024/8/1965V1.0  Confidential光通信测量-CSA7000B -Digital Filters -in the Optical Reference ReceiverO/EAcquisitionOC-3 Filter CoefficientsOC-12 Filter CoefficientsOC-48 Filter CoefficientsFC2125 Filter CoefficientsFilter Computation SoftwareCalibrationKnown Optical ImpulseCSA7000OperationO/EAcquisitionOC-48 Filter CoefficientsCSA7000 as OC-48 ORRWaveform Database2024/8/1966V1.0  Confidential光通信测量-CSA7000B-ORR – Performance and SimplicityIntegrated Optical Reference Receiver (ORR)Broad-wavelength, multimode O/E700 to 1650 nm, calibrated at 780, 850, 1310,1550 nmLibrary of ORR Digital Filters–4th-Order Bessel-Thompson filters–Easily disabled to provide full-bandwidth analysis on optical signals.–Eliminates the need for reconfiguring external accessories, modules or plug-insAllows easy optical/electrical Conformance Testing on a wide range of Comm standards up to 2.5 Gb/s with one instrumentInternal calibration ensures the accuracy and repeatability of results = confidence in measurements and design margins2024/8/1967V1.0  Confidential一个典型的SONET/SDH光纤传输系统收发单元示意图. The receiver's output interface provides regenerated data in a serialor parallel (deserialized) bit stream, along with the recovered clock.光通信测量-CSA7000B-Clock Recovery4在系统没有主时钟有效分布时需要采用在系统没有主时钟有效分布时需要采用Clock Recovery.0系统主时钟可以在研究室或机房等有效分配或布置系统主时钟可以在研究室或机房等有效分配或布置.0分布式系统时钟分布式系统时钟(不同地点不同地点)可以用可以用GPS接收机或时间接收机或时间-码产生机码产生机(time-code generators)进行同进行同步步(网络同步网络同步)  –称为称为1层时钟层时钟(Stratum 1 clocks) (highest level accuracy, synchronization).0Clock Recovery提供相对精度低点提供相对精度低点,低级别的同步低级别的同步(抖动抖动, PLL 相关相关).2024/8/1968V1.0  Confidential光通信测量-CSA7000B-Clock RecoveryClock and Data Recovery (CDR) circuit functions:–First to recover the clock signal (CR) from the received data stream (input signal).–Use the CR to perform timing and amplitude-level decisions on the incoming signal.–Regenerate the data stream (DR), with timing and amplitude characteristics, synchronized with the recovered clock (CR) or regenerated system clock. 4Phase-Locked Loop (PLL) necessary for clock recovery:0Fully integrated and does not require an external reference clock. 0Ensure alignment of the clock with the middle of a data word.0Monitors the CR and provides a Loss-of-Lock (LOL) alarm when the PLL loses lock.0for Optimized bit error rate (BER) – adjust clock phase relative to the data signal.4Jitter specifications – the real challenge for integrated CDRs:0Jitter specifications are recommended by the ITU/ Bellcore – e.g.  The OC-48, 2.488 Gb/s specs transmitter jitter-generation of 0.01 UIRMS (4 psRMS) and receiver jitter tolerance of 0.15 UIPk-Pk (60 psPk-Pk).  One bit Unit-Interval (UI) = 1/2.488Gb/s = 400 ps.0“Eye diagrams" best illustrate the signal quality of a serial data stream – this can be done directly (Measurements) or referenced to an "eye mask“ (Mask Test).2024/8/1969V1.0  Confidential光通信测量-CSA7000B-Clock RecoveryCSA7404B – Built-in CR for optical and electrical serial data streams from 1.5 Mb/s to 2.5 Gb/sIntegrated CR in an oscilloscope–Provides single-connection convenience–Can be used internally for trigger pick-off–Improves internal jitter performanceEye diagram analysis and mask test with more confidence–Jitter and pattern dependencies are not hidden by triggering on the data streamCR and DR Outputs (on CSA7000s only) –Max 1.25 Gb/s CR and DR on outputs–Recovered Clock Out (CR) and Regenerated Data Out (DR) from specified channel, available on SMA front-panel connectors for use with other test equipment (e.g. BER analyzers)2024/8/1970V1.0  Confidential。