- 學位論文
抑制次世代高速差動介面的電磁暨射頻干擾之微型化共模濾波器
Miniaturized Common-Mode Filters for EMI/RFI Mitigation in Next-Generation High-Speed Differential Interfaces
摘要
本文提出三種新穎的共模雜訊抑制電路，以解決差動數位信號通過傳輸介面時造成的共模雜訊輻射干擾。由於電磁及射頻干擾問題易發於高整合度的電路系統，除了達成需求的電氣特性外，微型化的電路設計技術亦是設計者追求的目標。透過對稱電路的分析技巧，本文提出的三種新型且微小的電路架構均被完善的分析，並詳述其電路設計流程。 有別於週期性的設計概念，本文首先使用單一單元的結構來設計微型化共模濾波器，再透過兩個共模傳輸零點達成寬頻的抑制效果，且控制零點的關鍵參數也由等效電路分析找出。藉由本文提出的最佳化設計流程，此概念被實現於多層的印刷電路板中，其電氣尺寸僅有0.11 λg × 0.11 λg，是基板內埋式共模濾波器中尺寸最小的。同時，此結構的共模雜訊抑制頻寬超過100%，並對於5 Gb/s的高速數位信號維持良好的眼圖特性。 為了更進一步地縮小電路尺寸，本文再提出一新型集總式電路架構來實現共模濾波器。根據奇偶模分析，差模態電路具有全通響應，而共模態電路為一具有兩傳輸零點的帶止濾波器，任意兩傳輸零點的合成設計公式亦在本文中提出，並將此集總式電路架構實現於被動積體電路製程中，藉由先進封裝製程的幫助，此電路可製作成極微小的表面貼片式元件，物理尺寸僅有1 mm × 0.95 mm。 最後，鑒於被共模濾波器反射的共模雜訊可能再度誘發未知的輻射干擾，一種全新的共模吸收電路設計概念亦在本文中提出。適當的設計電阻於電路中，電路可在共模態達成寬頻的吸收特性；在差模態中，此電路則為一個具有極高截止頻率的低通濾波器。因吸收特性成立的條件嚴格，對於集總元件的寄生效應非常敏感，故此電路亦建議實現於被動積體電路製程，此電路的物理尺寸僅有1 mm × 1 mm。值得注意的是，本文是第一個提出使用雜訊吸收概念來解決電磁干擾問題。
並列摘要
Three novel common-mode noise suppression circuits are proposed in this dissertation for addressing noise emission from high-speed digital differential input/output (I/O) interfaces. Because electromagnetic interference (EMI) or radio-frequency interference (RFI) is a common issue in highly integrated systems, the miniaturization is a crucial technique, except the required electrical specifications. By symmetrical network analysis techniques, three novel and compact CMFs are analyzed completely and the corresponding design procedures are demonstrated in detail as well. At first, a miniaturized CMF is designed by using single-cell structure, instead of periodic structures. Two common-mode transmission zeros are found by circuit analysis, and key parameters to control the zeros are also presented. A testing sample is realized in multilayer printed circuit board (PCB) with the optimized design procedures. The electrical size is the smallest one in packaged-embedded CMFs, which is only 0.11λg square. Meanwhile, the common-mode suppression bandwidth can be beyond 100%. Good signal integrity is also preserved well for 5 Gb/s data rate. Next, a new lumped circuit topology is proposed for further shrinking the size of CMF. Based on even/odd mode analysis, it has a all-pass response for differential mode, and a bandstop response with two transmission zeros for common mode. In this dissertation, two arbitrary transmission zeros can be synthesized by proposed design formulas. It is implemented by Integrated Passive Device (IPD) process and is available to be a surface mounted device (SMD) component. The fabricated sample is only 1 mm × 0.95 mm. Finally, a novel concept of common-mode noise absorption is proposed because the reflected common-mode noise due to CMFs may cause unexpected emission. The absorptive CMF (A-CMF) possesses a feature of wideband absorption for common mode by properly using resistors. For differential mode, it is a low-pass filter with an ultra-wideband cut-off frequency. Owing to strict requirements for holding the condition of absorption, the result is very sensitive to the parasitic effects of lumped elements. It is suggested to be fabricated by IPD process, which has a slight parasitic effects below 10 GHz. The circuit size is only 1 mm square. It is worth noting that it is the first article to employ noise absorption concept for solving EMI issues.
參考文獻
延伸閱讀
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