本論文針對利用差動訊號進行高速訊號傳輸之路徑，以及可應用於雙工通訊系統之I/O connectors，例如USB3.0，以及具有交替作用之USB Type-C，若在差動訊號傳輸時遭遇各種不理想效應，例如:時間延遲、振幅不相等，或是受到外界之無線頻率干擾，都容易在訊號傳輸過程中造成「共模雜訊」之產生，而若沒有加以受到抑制，則會進而輻射影響旁側電路架構，形成電磁干擾問題。
為了加以抑制共模雜訊則提出了「共模濾波器」之概念，主要分為反射型共模雜訊濾波器以及吸收型共模雜訊濾波器，而本論文主要設計為吸收型之共模雜訊濾波器，並針對與Wi-Fi頻段可能造成之頻率干擾，故將雙頻設定為2.4 GHz以及5.5 GHz，且因雙工通訊系統，共模雜訊可能由差動訊號之兩側出現，故希望可以達到雙頻且雙向吸收共模雜訊之效果，且在設計上提出了對稱式之電路架構，在電路面積上可大幅減少。
綜合上述，此論文提出之雙頻雙向吸收型共模雜訊濾波器，不但電路面積小，且架構相對簡單，並能夠維持良好之訊號完整性特性。

In this article,discusses the differential signals used approach for the transmission of high-speed digital signals,and can be applied to duplex communication systems,such as USB 3.0 and have alternate modes like USB Type-C.However,nonideal layouts,such as time skews ,asymmetry structures and interference from external wireless frequencies. These CM signals are seen as undesirable noise in differential signaling systems,which has become a severe electromagnetic interference(EMI) problem.Those EMI emissions may interfere wireless antennas nearby.
Therefore,developing a proper common mode filter(CMF) is an important issue for differential signaling systems.The one type of CMF is reflective-type common mode noise filter(RCMF),another is absorptive-type common mode noise filter(ACMF). The main design of this article is aimed at addressing frequencies interference that may be caused by the Wi-Fi bands.Therefore,dual-band are set to 2.4GHz and 5.5GHz,and because we want to apply to duplex communication systems,CM noise may appear on both sides of the differential signal.Therefore, it is hoped that the effect of bidirectional absorptive common mode noise and designed a symmetrical circuit architecture can significant reduce the circuit size.
In summary,this article proposes a bidirectional absorption and dual-band common mode noise filter that not only achieved a small circuit size and has a simple structure but also maintains well signal integrity characteristics.

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