无源共模滤波器滤波性能的在线与离线测量

Online and offline measurements of passive common-mode filter performance

与有源共模滤波器相比,无源共模滤波器具有结构简单、成本低廉等优点,但其滤波性能易受元件寄生参数和饱和特性影响。该文针对一个LC二阶无源共模滤波器,分别基于离线测量和在线测量提取了其电感和电容的寄生参数,分析了离线参数与在线参数的异同。对插入损耗进行了离线测量和在线测量。结果表明:离线测量能反映磁心材料的频率特性,但不能反映饱和特性;而在线测量受制于测量仪器的性能,很难反映宽频率范围的频率特性。因此,对无源共模滤波器,离线测量所得滤波性能不能充分反映在线测量的滤波性能。

Passive common-mode filter （CMF） has the advantages of simple structure and low cost over active CMF,but its high frequency performance is vulnerable to parasitics and saturation. This paper focuses on a 2nd order LC passive CMF,with offline and online measurements respectively used to extract the parasitics of its components including inductors and capacitors. Offline and online parameters were compared with the insertion loss measured offline and online,respectively. The results show that the offline measurement can discover the frequency characteristics,but fails to reveal the saturation features of magnetic core materials while the online measurement fails to obtain wide-range frequency characteristics due to the instrument limitation. Therefore,filtering performance by the offline measurement cannot fully reflect the realistic filtering performance by the online measurement for a passive CMF.