一用於兆赫層級差動信號傳輸兼具寬頻共模濾波特性之新穎差模等化器

Abstract

在運用各種耦合傳輸線的高速差動信號傳輸系統中，維持差模信號的傳輸品質以及有效地抑制共模雜訊是確保接收端具有良好信號完整度的決定性因素。為此，我們提出了一個結合共模濾波器效果的新式被動等化器，其除了能夠等化差模信號外亦能過濾共模雜訊，名為「VCPW-R」。所提出之等化器可製作於封裝或印刷電路基板上，其具有價格低廉、體積小以及適用於不同傳輸速率之優點。 本論文將會先介紹幾種常見的耦合傳輸線，之後再描述所提出結構(即VCPW-R)的整體架構與相應的等效電路模型。此結構於差模及共模的傳輸特性分別利用奇模和偶模半電路進行分析。此外，我們也對此結構提出一個兼顧差模與共模傳輸特性之共設計流程，利用此設計流程針對8 Gb/s差動傳輸找出一組設計參數並用於實作測試電路板。根據實作板的頻域及時域量測結果，所提出結構之差模等化及共模濾波效果成功地獲得驗證。

In high-speed differential signal transmission using various kinds of coupled lines, good signal integrity (SI) at the receiving end is mainly attributed to high quality of the transmitted differential-mode signal and effective suppression of the generated common-mode noise. In view of this, an innovative passive equalizer able to not only equalize differential-mode signals but also filter common-mode noise, named “VCPW-R”, is proposed so that the two modes can be well treated with a low cost, compact and adaptable structure on a package or PCB substrate. After the discussion of the characteristic of typical coupled lines, the configuration and corresponding equivalent model of the proposed VCPW-R is described. The characteristics of the proposed structure under differential-mode and common-mode transmission are discussed separately with the corresponding half-circuit models. Based on the proposed co-design flow, which takes both modes into consideration, a set of the design parameters are determined for 8 Gb/s differential transmission and utilized in the fabrication of test boards. The frequency-domain and time-domain measurements of the test board successfully demonstrate the effectiveness of the proposed structure.