仿真分析在时钟电路电磁兼容设计中的应用

从抑制时钟电路电磁辐射出发，介绍了时钟电路电磁兼容设计时线条阻抗设计方法，以及传输线延迟的计算、减小时钟电路电磁辐射的几种方法，仿真分析了时钟电路电磁辐射值与线条长度、信号上升沿以及保护线的关系，并计算了保护线的屏蔽效能。结果表明在整个频谱范围内，电磁辐射值随时钟信号上升沿减小而增大；随时钟线条长度增加，辐射尖峰相对于短线条的辐射增多；保护线对时钟电路的电磁辐射有明显抑制作用。

Application of simulation analysis in electromagnetic compatibility design of clock circuit

The electromagnetic compatibility design of the impedance of clock line, the calculating method of delaying time of transmission line, and the ways to decrease electromagnetic radiation are introduced based on restraining electromagnetic radiation of clock circuit. The shielding effect of the protective line is calculated, and the electromagnetic radiation of the clock circuit line in different lengths and different rising time are analysed by simulation. The results indicate that the electromagnetic radiation is increasing with the decreasing of rising time of clock signal, while the radiated peaks are increasing with the increasing of the length of clock line, and the protective line can restrain the electromagnetic radiation of clock circuit remarkably.