顯著降低共模雜訊之不同佈線層弱耦合差模蛇形延遲微帶線

Significant Reduction of Common-Mode Noise in Weakly Coupled Differential Serpentine Delay Microstrip Lines Using Different-Layers-Routing Structure

廖桓毅(Huan-Yi Liao)

指導教授 ： 薛光華

中原大學/工學院/電子工程研究所/碩士(2014年)

https://doi.org/10.6840/cycu201400459

摘要

本論文提出新的弱耦合差模蛇形延遲微帶線結構，其目的在於減少共模雜訊。此新提出的結構中，主要藉由差模蛇形延遲微帶線結構在轉角處不同層的走線來代替傳統結構中的同層走線，所以新結構名稱為轉角換層式差模蛇形延遲微帶線，而此新結構又可分為兩種設計方案，一種是阻抗完全匹配的原始方案，另一種是含有縮減線寬高阻抗線段的改善方案。
本文所提出的轉角換層式差模蛇形延遲微帶線的改善方案在時域共模電壓峰對峰值抑制的比較中顯示，其抑制效果比一般傳統方案抑制共模雜訊超過將近90%左右。另外在頻域的差模與共模轉換結果顯示，在0.8GHz~16GHz 的頻率範圍中，轉角換層式差模蛇形延遲微帶線的改善方案抑制共模雜訊效果至少20dB 以上。經過分析後得知，具有高阻抗線段的改善方案相對於阻抗匹配的原始方案有較好的訊號完整性。以頻率的觀點來看，結構的不對稱性將會影響在低頻共模雜訊的抑制效果。因此差模蛇形延遲線的共模雜訊抑制方案中，結構的對稱性是非常重要的。模擬和測量結果之間的比較有利的證實了本文所提出的方案具有很好的共模雜訊減少效果。

關鍵字

差模與共模轉換 ； 共模雜訊 ； 訊號完整性 ； 差模反射損失 ； 差模蛇形延遲微帶線

並列摘要

This work proposes a new structure to reduce the common-mode noise (CMN) in weakly coupled differential serpentine delay microstrip lines (DSDMLs). The proposed CMN reduction structure uses different-layers-routing turned traces as a substitute for same-layer-routing coupled turned traces (CTTs) (as in the conventional scheme). Base on the different-layersrouting turned traces, the proposed reduction schemes include the original reduction scheme, in which all traces are impedance– match, and improved reduction scheme, in which all traces are associated with high impedance (reduced trace width). The proposed solutions yield a peak-to-peak amplitude of CMN in the time domain than is more than 90% less than that obtained suing the conventional scheme. The DSDMLs with improved reduction scheme reduces the differential-to-common mode conversion (|Scd21|) by more than 20dB in the range 0.8GHz~16GHz. An investigation of why DSDMLs with the improved reduction scheme yield greater signal integrity than one using the original reduction scheme is performed. With respect to the frequency domain viewpoint, the asymmetry can destroy the efficiency of CMN reduction at low frequencies. Symmetry is an important requirement for DSDMLs with the proposed CMN reduction scheme. Finally, a favorable comparison between simulated and measured results confirms the excellent CMN reduction provided.

並列關鍵字

common-mode noise ； differential-to-common mode conversion ； differential serpentine delay microstrip lines ； differential reflection loss ； signal integrity

參考文獻

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