高速数字电路设计及EMC

h09721

??

??【文件名】:061021@52RD_高速数字电路设计及EMC设计.rar

??【格　式】:rar

??【大　小】:655K

??【简　介】:

??【目　录】:1.高速数字电路设计..........................................................................................................................51.1何谓高速数字信号？..................................................................................................................51.2微带线、带状线的概念..............................................................................................................51.2.1微带线（Microstrip）......................................................................................................51.2.2带状线（Stripline）.........................................................................................................61.2.3经验数据...........................................................................................................................61.2.4同轴线（coaxialcable）..................................................................................................61.2.5双绞线（twisted-paircable）..........................................................................................71.2.6等间隔的电容负载的影响...............................................................................................71.3常见高速电路.............................................................................................................................81.3.1ECL（EmitterCoupledLogic）电路...............................................................................81.3.2CML（CurrentModeLogic）电路.................................................................................91.3.3GTL（GunningTransceiverLogic）电路.....................................................................101.3.4BTL（BackplaneTransceiverLogic）电路...................................................................101.3.5TTL（TransistorTransistorLogic）电路......................................................................111.3.6模数转换电路—线接收器............................................................................................121.4常见电路匹配措施...................................................................................................................121.4.1反射................................................................................................................................121.4.2终端匹配.........................................................................................................................131.4.3始端匹配.........................................................................................................................151.5高速电路设计一般原则和调试方法.......................................................................................161.5.1同步逻辑设计.................................................................................................................161.5.2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。..............................................................................191.5.3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。.........................................................................................................................................191.5.4了解每一根高速信号电流的流向（电流环）.............................................................191.5.5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）..............................................................................................191.5.6电源滤波.........................................................................................................................191.5.7对很高速度的信号要估算其走线延迟。.....................................................................191.5.8在满足速度要求的前提下，尽量选用工作速率低的器件。.....................................191.5.9差分线尽量靠近走线.....................................................................................................191.5.10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。......................................................................................................191.5.11ringing,crosstalk,radiatednoise——数字系统的三种噪声....................................191.5.12数字信号的绝大部分能量（功率谱密度）集中在fknee之内.....................................191.5.13延时：FR4PCB，outertrace:140~180ps/inchinnertrace:180ps/inch..........201.5.14集总参数与分布参数系统..........................................................................................201.5.15互感、耦合电容的作用（干扰）..............................................................................201.5.16ECL电路的上升时间、下降时间的计算..................................................................201.5.17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。......................211.5.18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。.................................................................................................................................211.5.19阻容负载对电流变化的作用......................................................................................211.5.20噪声容限（noiseimmunity）：以10H189器件为例................................................221.5.21地反弹（groundbounce）.......................................................................................231.5.22寄生电容StrayCapacitance的影响：对于高输入阻抗电路影响尤为严重...........231.5.23示波器探针的电气模型..............................................................................................241.5.2421:1探针：...................................................................................................................251.5.25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。.................................................................................................................................251.5.26 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 1.5.30 TTL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（Electromagnetic Compatibility）...........................................................................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

??2.1.7 EMC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 2.3.2 If DC power planes can’t be used, then lumped decoupling capacitors must be sized and placed correctly.......................................................................................................................42 2.3.3 多层PCB、表贴电容，串联电感在何处？...............................................................43 2.3.4 How to distribute DC power from a single supply 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................................................................

??【文件名】:061021@52RD_高速数字电路设计及EMC设计(1).rar

??【格　式】:rar

??【大　小】:655K

??【简　介】:

??【目　录】:

??

??

??