參考層C型挖槽之差模訊號共模濾波器

Common-Mode Filter of Differential Signals with C-shaped Slot Line in Reference Plane

李智翔(ZHI-XIANG LI)

指導教授 ： 薛光華

中原大學/電機資訊學院/電子工程學系/碩士(2022年)

https://doi.org/10.6840/cycu202201377

摘要

本文以業界在使用的共模濾波器為原形並改善其結構，以達到更有效降低共模雜訊的目的。在業界實務中，使用參考層槽線(Slot)設計共模濾波器(Common-Mode Filter)，其設計為一對橫向差模訊號線跨越一開口向下的C型槽線結構，但該共模濾波器結構缺乏對稱性，這會使得共模雜訊增生，為解決結構的不對稱性，文中提出兩種改善結構，這兩種結構皆有效增加共模濾波效果和抑制不對稱結構造成的共模雜訊，透過模擬結果可知，改良後結構的時域共模雜訊值減少約98%，且能預測其抑制頻率點的位置，另外，訊號線跨槽線會使訊號線的阻抗不連續，造成反射並破壞訊號的完整性，本文也將一併分析呈現。

關鍵字

共模濾波器 ； 槽線 ； 訊號完整性

並列摘要

This paper takes the common mode filter used in the industry as the prototype and improves its structure to achieve the purpose of reducing common mode noise more effectively. In practice, it had been found that slot line in reference layer is used to design a common- mode filter, which was designed as a pair of horizontal differential signal lines crossed an opening downward C-shaped slot line. But, the common-mode filter structure which was used in practice lacks symmetry, it would increase common noise. In order to solve the structural asymmetry, two types of improved structures are proposed in the paper. Both of these structures effectively increase the common-mode filtering effected and suppress common-mode noise caused by asymmetric structures. The simulation results showed that the time-domain common-mode noise value of the improved structure was reduced about 98%, and the position of the suppressed frequency point could be predicted. In addition, the signal line crossing the slot line that will cause the impedance of the signal line to be discontinuous; it cause reflection and destroy the integrity of the signal. This paper will also analyze and present it.

並列關鍵字

Common-Mode Filter ； Slot ； Signal Integrity

參考文獻

[1] Stephen H. Hall, Garrett W. Hall, and James A. McCall, High-Speed Digital System Design – A Handbook of Interconnect Theory and Design Practices, New York: John Wiley & Sons, Inc, 2000.

[2] Spartaco Caniggia and Francescaromana Maradei, Signal Integrity and Radiated Emission of High-Speed Digital Systems, John Wiley & Sons, Ltd, 2008, pp. 284-287.

[3] Stephen H. Hall, HOWARD L. HECK, Advanced Signal Integrity for High-Speed Digital System Design, Hoboken, New Jersey: John Wiley & Sons, Inc, 2009.

[4] S. Lee, "Reduce Radiation of PCIe Gen3 / 4 Signal by Common Mode Filter Design," 2019 Joint International Symposium on Electromagnetic Compatibility, Sapporo and Asia-Pacific International Symposium on Electromagnetic Compatibility (EMC Sapporo/APEMC), 2019, pp. 424-427.

[5] David M. Pozar, Microwave Engineering, New York: John Wiley & Sons, Inc, 2012, pp. 48-50.