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<DIV class=quote><B>以下是引用<I>h09721</I>在2006-12-31 10:20:32的发言：</B>
??1.高速数字电路设计..........................................................................................................................5
??1.1何谓高速数字信号？..................................................................................................................5
??1.2微带线、带状线的概念..............................................................................................................5
??1.2.1微带线（Microstrip）......................................................................................................5
??1.2.2带状线（Stripline）.........................................................................................................6
??1.2.3经验数据...........................................................................................................................6
??1.2.4同轴线（coaxialcable）..................................................................................................6
??1.2.5双绞线（twisted-paircable）..........................................................................................7
??1.2.6等间隔的电容负载的影响...............................................................................................7
??1.3常见高速电路.............................................................................................................................8
??1.3.1ECL（EmitterCoupledLogic）电路...............................................................................8
??1.3.2CML（CurrentModeLogic）电路.................................................................................9
??1.3.3GTL（GunningTransceiverLogic）电路.....................................................................10
??1.3.4BTL（BackplaneTransceiverLogic）电路...................................................................10
??1.3.5TTL（TransistorTransistorLogic）电路......................................................................11
??1.3.6模数转换电路—线接收器............................................................................................12
??1.4常见电路匹配措施...................................................................................................................12
??1.4.1反射................................................................................................................................12
??1.4.2终端匹配.........................................................................................................................13
??1.4.3始端匹配.........................................................................................................................15
??1.5高速电路设计一般原则和调试方法.......................................................................................16
??1.5.1同步逻辑设计.................................................................................................................16
??1.5.2了解选用器件的输入、输出结构，选用恰当的匹配电路；在考虑节省功耗，电路又能容许的情况下，可适当地引入失配。..............................................................................19
??1.5.3对极高速率（300MHz以上）的信号，一般建议选用互补逻辑，以降低对电源的要求。.........................................................................................................................................19
??1.5.4了解每一根高速信号电流的流向（电流环）.............................................................19
??1.5.5信号的布线、电源和地层的分割，是否符合微带线、带状线的要求？高速信号要有回路地相配（不是屏蔽地）..............................................................................................19
??1.5.6电源滤波.........................................................................................................................19
??1.5.7对很高速度的信号要估算其走线延迟。.....................................................................19
??1.5.8在满足速度要求的前提下，尽量选用工作速率低的器件。.....................................19
??1.5.9差分线尽量靠近走线.....................................................................................................19
??1.5.10测试方法：选择有50Ω输入的高速示波器，一般自制一个探头，测量点应尽量靠近所观察的位置或者需要该信号的实际位置。一般不建议测输出端的信号波形，与实际
??2
??使用的位置有一定差别。......................................................................................................19
??1.5.11ringing,crosstalk,radiatednoise——数字系统的三种噪声....................................19
??1.5.12数字信号的绝大部分能量（功率谱密度）集中在fknee之内.....................................19
??1.5.13延时：FR4PCB，outertrace:140~180ps/inchinnertrace:180ps/inch..........20
??1.5.14集总参数与分布参数系统..........................................................................................20
??1.5.15互感、耦合电容的作用（干扰）..............................................................................20
??1.5.16ECL电路的上升时间、下降时间的计算..................................................................20
??1.5.17在数字系统中，耦合电容引起的串扰比起互感引起的串扰要小。......................21
??1.5.18传输通道包括器件封装、PCB布局、连接器，至少在fknee的范围内要有平坦的频响，以保证信号不失真，否则信号在收端可能会遇到上升时间劣化、过冲、振铃、lump等现象。.................................................................................................................................21
??1.5.19阻容负载对电流变化的作用......................................................................................21
??1.5.20噪声容限（noiseimmunity）：以10H189器件为例................................................22
??1.5.21地反弹（groundbounce）.......................................................................................23
??1.5.22寄生电容StrayCapacitance的影响：对于高输入阻抗电路影响尤为严重...........23
??1.5.23示波器探针的电气模型..............................................................................................24
??1.5.2421:1探针：...................................................................................................................25
??1.5.25趋肤效应（skineffect）：在高频时导线表面附近的电流密度加大，而中心部分的电流密度减小。趋肤效应使得导线对高频信号的衰减增大。趋肤效应的频率与导体的材料有关。.................................................................................................................................25
??1.5.26对低频信号，电流流经电阻最小的路径；对高频信号，回流路径的电感远比其电阻重要，高频电流流经电感最小的路径，而非电阻最小的路径。最小电感回流路径正好在信号导线的下面，以减小流出和流入电流通路间的环路面积。..................................25
??1.5.27负载电容对上升时间的影响......................................................................................26
??1.5.28直流匹配和交流匹配的功耗比较..............................................................................27
??1.5.29电源系统设计原则......................................................................................................27
??1.5.30TTL和ECL的混合系统要注意.................................................................................27
??1.5.31电源线上的电磁辐射防护..........................................................................................28
??1.5.32旁路电容的选取和安装：..........................................................................................28
??1.5.33连接器对高速系统的影响..........................................................................................28
??1.5.34总线：..........................................................................................................................30
??2、电磁兼容性（ElectromagneticCompatibility）...........................................................................32
??2.1关于电磁兼容性的基本原理...................................................................................................32
??2.1.1下面的电路布局有什么问题？.....................................................................................32
??2.1.2走线可穿过回流平面的缝隙吗？No！.......................................................................33
??2.1.3走线的电感和电容.........................................................................................................33
??2.1.4接地的作用：.................................................................................................................34
??2.1.5信号参考点应在何处接至基底(chassis)......................................................................35
??2.1.6周期信号........................................................................................................................36
??3
??2.1.7EMC三要素...................................................................................................................36
??2.1.8共模和差模.....................................................................................................................38
??2.1.9减小噪声的措施............................................................................................................39
??2.2信号完整性――减小串扰和信号畸变...................................................................................39
??2.2.1.........................................................................................................................................39
??2.2.2屏蔽................................................................................................................................40
??2.2.3信号畸变........................................................................................................................41
??2.3通过滤波减小直流电源噪声...................................................................................................41
??2.3.1.........................................................................................................................................42
??2.3.2IfDCpowerplanescan’tbeused,thenlumpeddecouplingcapacitorsmustbesizedandplacedcorrectly.......................................................................................................................42
??2.3.3多层PCB、表贴电容，串联电感在何处？...............................................................43
??2.3.4HowtodistributeDCpowerfromasinglesupply to both analog and digital circuits?..43
??2.4 元件放置与信号层分配...........................................................................................................44
??2.5 Reducing conducted & radiated emission & susceptibility........................................................46
??2.6 电路板EMC准则总结............................................................................................................48
??2.6.1 Component Placement....................................................................................................48
??2.6.2 DC Power Distribution....................................................................................................48
??2.6.3 Routing of Signal Output and Return Paths....................................................................49
??2.6.4 Signal Integrity – Reducing Crosstalk and Distortion.....................................................49
??2.6.5 High Frequency Transmission Lines...............................................................................50
??2.6.6 Reducing Conducted and Radiated Emissions................................................................50
??4
??【文件名】:061231@52RD_高速数字电路设计及EMC设计(1).pdf
??【格 式】:pdf
??【大 小】:773K
??【简 介】:
??【目 录】:
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