使用防护布线减小差分传输线间的高频串扰噪声

随着高速电路的不断发展，差分传输线得到了越来越广泛的应用。它具有低辐射和较好的抗共模噪声能力。但是传统的差分线结构不能有效的降低邻近差分对之间的串扰噪声，这将影响到高速系统的信号完整性。文章针对使用防护布线的方法，讨论了三种不同结构的防护布线，在全波电磁仿真软件HFSS中建立了三维物理模型，利用混模S参数分析了它们对于减小串扰噪声的作用，从场的角度对比了它们的电磁屏蔽效果，并对如何使用防护布线提出了一些建议。

Using Guard Traces for Crosstalk Reduction between High Frequency Differential Lines

With the continuous development of high speed circuit, differential transmission lines are more and more widely used for layout. And they have low-radiation emission and high common-mode noise immunity. However, conventional differential line structures still suffers from crosstalk between neighboring differential pairs, thus affecting the signal integrity of high speed system. Aim at using guard trace, there are three kinds of guard trace structure which are discussed in this paper. 3-D physical models are established in a full wave EM Simulation software HFSS. Their effects for alleviating crosstalk are analyzed in mix-mode S-parameters, and then their impacts of electromagnetic shield are compared respectively. Some recommendations for using guard trace are proposed.