本論文主要目的為利用緩和折彎抑制折彎差動微帶線的共模雜訊，並且應用在印刷電路基板上。先藉由緩和折彎以降低內外線的不平衡，再把S參數轉換成ABCD矩陣，並且利用集總元件等效電路計算出各個緩和折彎後的等效電容值與等效電感值，再藉由公式計算出補償所需面積，並在使用最小面積來補償先前的不平衡，以減少共模雜訊的產生。在頻域分析上，其差模轉共模損耗從DC到高頻6GHz皆能比原本的90/135/150度與圓弧折彎差動微帶線來的好3dB 以上。在時域分析上能有效降低共模雜訊電壓，且從眼圖中得知此結構能夠維持良好的訊號品質。最後根據模擬與實驗結果可進一步證明本文所提出有限面積下利用緩和折彎結構能有效降低其共模雜訊，同時還能維持良好的差模訊號完整性。

In this paper, we propose to use moderated bend to suppress common mode noise in the bent differential transmission line in limited area. By moderated bend to reduce the imbalance between the inner and outer lines, and then converting the S parameter into the ABCD matrix. Using the equivalent circuit of the lumped element to calculate the equivalent capacitance and the equivalent inductance of each moderated bend, and then calculating the compensation area by using the formula. Using the minimum area to compensate for the previous imbalance to reduce the common-mode noise.In the frequency domain analysis, The differential mode common mode conversion loss from DC to high frequency 6GHz is higher than the original 90,135,150 degree and arc bend differential microstrip line of more than 3 dB. In the time domain analysis, the common mode noise voltage can be effectively reduced, and it is known from the eye diagram that the structure can maintain good signal quality. Finally, based on the simulation and experimental results, it can be further proved that the use of the moderate bending structure under the limited area proposed in this paper can effectively reduce the common mode noise and maintain good differential mode signal integrity.

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