以HU形狀之缺陷式接地面設計高速差模訊號中 寬頻共模濾波器研究

Abstract

本論文提出一種新型的共模濾波器，此共模濾波器是利用新型式缺陷式接地面(Defected Ground Structure)結構所組成。透過共振器之間的耦合關係，可以縮減缺陷式接地面結構的尺寸面積且適用於高頻訊號及具有寬頻雜訊抑制效果。另外，此共模濾波器設計在印刷電路版中，不同於傳統共模扼流圈(Common-modechoke)必須外接於電路架構之外。 本文將針對缺陷式接地面結構的各物理尺寸參數與特性變化作分析，進而分析其耦合結構特性，並建立出等效電路模型與實驗結果比較。在時域分析中，此共模濾波器對共模電壓的抑制效果達到了60％以上。而在電磁干擾的量測中，此共模濾波器在所設計的抑制頻帶上可抑制共模訊號輻射達到10dB以上。

A broadband common-mode suppression filter for Gbps differential signals using a novel defected ground structure is proposed in this thesis. Unlike traditional common-mode choke using ferrite material, this kind of common mode filter with high frequency and broadband common-mode noise suppression capability can be embedded in printed circuit board without increasing any extra cost. We focus on the study of the physical size parameters, characteristic behavior of the defected ground structure, and coupling effect between DGS resonators. The equivalent circuit model is also proposed and presents good consistency with the measurement result. In time domain analysis and measurement of the DGS common-mode filter, the common-mode noise due to the differential signal skew can be suppressed more than 60% for the proposed filter. In EMI measurement, it is verified that common-mode filter can suppress common-mode noise more than 10 dB within the stop-band.