传输线耦合下的差分对共模特性分析  

Common mode characteristic analysis of differential pair with transmission line coupling

作　　者：丁同浩[1] 李玉山[1] 

机构地区：[1]西安电子科技大学电路CAD研究所,西安710071

出　　处：《仪器仪表学报》2011年第7期1485-1492,共8页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金(No.60672027;No.60871072)资助项目

摘　　要：基于差分信号奇模和偶模特性,分析和研究了传输线耦合对差分传输线的影响,研究表明由于传输线间的边缘场耦合,差分传输线的特性阻抗和传输时延均发生改变,从而引发阻抗不连续和信号错位,并最终导致共模噪声和EMI等信号完整性问题。传输线与差分传输线的耦合距离越小,耦合电容的不对称性就越大,引发的共模噪声也就越大。最后通过频域和时域实验验证了共模特性理论分析,实验结果表明,传输线与差分传输线间的两倍线宽间距将有效减小传输线与差分传输线耦合的差异,从而降低共模噪声和阻抗不连续以提高信号传输质量。The effect of transmission line coupling on differential transmission lines is investigated in terms of odd and even mode characteristics of differential signals.It is found that the characteristic impedance and delay time of the differential transmission lines are changed due to the fringe field coupling between transmission lines,so impedance mismatch and skew are induced,which result in common mode noise and EMI.The smaller the coupling space between transmission line and differential pair is,the larger the unbalance of capacitance coupling is,and larger common mode noise is produced.Finally,experiments in frequency domain and time domain are used to verify the analysis of common mode characteristics;experiment results validate that enlarging the space between transmission lines and differential transmission lines to twice the line width could effectively decrease the coupling difference,suppress common mode noise and impedance mismatch,and improve signal transmission quality.

关 键 词：奇模 偶模 差分传输线 共模噪声 

分 类 号：TN811[电子电信—信息与通信工程]