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高速数字电路设计和EMC
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目 录
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（coaxial cable）...........................................................................................6
1.2.5 双绞线（twisted-pair cable） ....................................................................................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
1.3.1 ECL（Emitter Coupled Logic）电路..........................................................................8
1.3.2 CML（Current Mode Logic）电路.............................................................................9
1.3.3 GTL（Gunning Transceiver Logic）电路..................................................................10
1.3.4 BTL（Backplane Transceiver Logic）电路...............................................................10
1.3.5 TTL（Transistor Transistor Logic）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，与实际使用的位置有一定差别。19
1.5.11 ringing, crosstalk, radiated noise —— 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：FR4 PCB，outer trace: 140180 ps/inch inner trace: 180 ps/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
1.5.16 ECL 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（noise immunity）：以10H189 器件为例...............................................22
1.5.21 地反弹（ground bounce）.............................................................................23
1.5.22 寄生电容Stray Capacitance 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.......................................................................................23
1.5.24 21:1 探针：..........................................................................................................25
1.5.25 趋肤效应（skin effect）：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
1.5.30 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） ................................
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
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
4
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 .................................................45
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
【文件名】:0886-HSBD&EMC.pdf
【目 录】:
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（coaxial cable）...........................................................................................6
1.2.5 双绞线（twisted-pair cable） ....................................................................................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
1.3.1 ECL（Emitter Coupled Logic）电路..........................................................................8
1.3.2 CML（Current Mode Logic）电路.............................................................................9
1.3.3 GTL（Gunning Transceiver Logic）电路..................................................................10
1.3.4 BTL（Backplane Transceiver Logic）电路...............................................................10
1.3.5 TTL（Transistor Transistor Logic）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，与实际使用的位置有一定差别。19
1.5.11 ringing, crosstalk, radiated noise —— 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：FR4 PCB，outer trace: 140180 ps/inch inner trace: 180 ps/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
1.5.16 ECL 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（noise immunity）：以10H189 器件为例...............................................22
1.5.21 地反弹（ground bounce）.............................................................................23
1.5.22 寄生电容Stray Capacitance 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.......................................................................................23
1.5.24 21:1 探针：..........................................................................................................25
1.5.25 趋肤效应（skin effect）：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
1.5.30 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） ................................
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
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
4
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 .................................................45
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
【文件名】:0886-HSBD&EMC.pdf
【目 录】:
谢谢楼主
谢谢呀，！
多谢 顶
xiexie
很不错的哦
支持免费！
顶！谢谢楼主
谢谢lz，总结的很经典，还是免费。
ding
好东西,谢谢啊
thanks！
thanks！
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