近年來單端傳輸電路已經逐漸被差動傳輸電路所取代，主要的原因是差動傳輸電路有低雜訊產生且高共模雜訊抑制的能力，但差動傳輸電路對於電路的品質要求也相對的較高，差動傳輸電路之兩條訊號線必須等長且對稱，然而實際的電路板受限於空間必然會經過繞線或是彎折的情形，造成訊號不連續而產生信號完整性及電磁輻射問題。
在本論文中，提出了一個新穎的差動訊號傳輸結構，可抑制因轉折所產生的共模雜訊，跟傳統的邊緣耦合轉角傳輸線比較，在頻率10GHz內可以抑制共模轉換雜訊超過20dB，並且可以保持差模訊號的插入損失不會因為經由轉折而產生過大的損耗，並且在TDT共模雜訊分析中與傳統轉折邊緣耦合微帶線相較之下可抑制共模雜訊電壓達91%，最後的量測與模擬結果也吻合。但由於此結構沒有一個參考的接地面迴流路徑不完全，使得電流容易輻射出去，故最後吾人設計了防護線去降低此結構的電磁輻射效應。

In recent year, the single-end transmission line is instead by differential transmission line . Differential signaling has been generally used in the high speed digital interconnection on the PCBs. The advantages of the differential signal with a low noise and high common-mode noise suppression, but the differential mode transmission signal is a very high quality requirements of circuit, the two line should have same length and symmetry, but in the practical package the circuit is not this case, In the limit space ,the differential signal should through the bend, it would lead to the phase skew and produce the differential to common mode conversion noise on the signal integrity and electromagnetic interference(EMI) problem.
In this paper a new type of bend is proposed that reduces differential -to-common mode conversion noise for high speed digital circuit. This novel structure can reduce the mode conversion over 20dB at DC to 10GHz, and the differential insertion loss remains low. Also time domain the TDT common mode noise from 0.09V to 0.008V as compared with the bended differential transmission line using the edge couple bend. Moreover, the measurement on proposed structure show a close match with the full-wave simulation result. However, this structure does not have a reference plane, the return path is not complete, the current is easy to radiate out, so I design a guard trace to reduce the radiation in this structure.

摘要 i
Abstract ii
目錄 iii
表目錄 iv
圖目錄 v
第 1 章 序論 1
1-1 研究目的與動機 1
1-2 論文大綱 2
第 2 章 差動傳輸線之特性 3
2-1 差動訊號線 3
2-2奇模與偶模的傳輸原理 5
2-3 混合模態散射參數 10
第 3 章 共模雜訊之抑制 17
3.1不對稱之傳輸線導致模態轉換 17
3.1.1共模阻抗的影響 18
3.2新式差動傳輸結構設計改善共模雜訊 22
3.3模擬與實驗之驗證 29
3.3.1 TDT共模雜訊分析 33
3.3.2眼圖分析 35
第 4 章 新式差動對結構之電磁輻射效應與改進 39
4.1利用混合模態探討電磁輻射效應 40
4.2利用防護線改善電磁輻射效應 41
第 5 章 結論 48

[1] S. Connor, B. Archambeault, and M. Mondal, “The Impact of Common Mode Currents on Signal Integrity and EMI in High-Speed Differential Data Links,” in IEEE Int. Symp. Electromagn. Compatibil., Aug. 2008,pp. 680–684.

[2] Ding-Bing Lin; Ji-Liang Pan , “Analysis and Improvement on Propagation Efficiency of High-speed Asymmetric Differential Transmission System,” in IEEE 2004 Asia-Pacific Conference on pp329-332 vol 1

[3] G.-H. Shiue, W.-D. Guo, C.-M. Lin, and R.-B. Wu, “ Noise reduction using compensation capacitance for bend discontinuities of differential transmission lines,”IEEE Trans. Adv. Packag., vol. 29, no. 3, pp.560–569, Aug. 2006.

[4] S.-J. Wu, C.-H, Tsai, T.-L. Wu, and T. Itoh, "A Novel Wide Band Common mode Suppression Filter for Gigahertz Differential Signals Using Coupled Patterned Ground Structure," IEEE Trans. Microw. Theoy. and Tech.,vol. 57, no.4, pp. 848-855, Apr. 2009.

[5]　 D. M. Pozar, Microwave Engineering, 3rd ed., John Wiley & Sons, New York,
2005.

[6] 　W. Fan, A. Lu, L. L. Wai, and B. K. Lok, “Mixed-mode S-parameter characterization of differential structures,” in Proc. IEEE 5th Electronics
Packaging Technology Conf., pp. 533-537, Dec. 2003.

[7]　H. Howard, H. Stephen, H. Bryce, and L. Tao, “Modeling and mitigating
AC common mode conversion in multi-Gb/s differential printed　circuit boards,” in Proc. IEEE 13th Topical Elect. Performance Electron Packag., Oct. 2004, pp. 29–32.

[8] ADS 2005A,Agilent Technologies (www.agilent.com)

[9] Orhanovic, N., Raghuram, R., Matsui, N., “ Signal propagation and radiation of single and differential microstrip traces over split image planes, ” 2000 International symposium on Electromagnetic compatibility,pp. 339-343, vol.1, 2000.


[10] 　薛光華,“差模轉角與信號線跨槽不連續結構之模型化、分析與設計,”國立台灣大學電機工程學系博士論文, 2006.

[11] 　黃志億,“封裝基板上差動對繞線設計之研究,” 國立中山大學電機工程學系碩士論文, July 2007.

[12] D. E. Bockelman and W. R. Eisenstadt, “Pure-mode network analyzer for onwafer measurements of mixed-mode s-parameters of differential circuits,” IEEE
Trans. Microwave Theory Tech., vol. 45, pp. 1071–1077,July 1997.

[13] 　Gazda, C.; Vande Ginste, D.; Rogier, H.; Ruey-Beei Wu; De Zutter, ”A Wideband Common-Mode Suppression Filter for Bend Discontinuities in Differential Signaling Using Tightly Coupled Microstrips”IEEE Transactions on Advanced Packaging, Vol. 33, NO. 4, November 2010.

[14] 　Dong Gun Kam; Heeseok Lee ; Joungho Kim,”Twisted Differential Line Structure on High-Speed printed Circuit Boards to Reduce Crosstalk and radiated Emission”IEEE Transactions on Advanced Packaging, Vol. 27, NO. 4, November 2004

[15] 　C. R. Paul, Introduction to Electromagnetic Compatibility, 2ed ed., John Wiley &Sons,2006.

[16] 　M.R. Burford, P.A. Levin and T.J. Kazmierski,　”Temporal skew and mode conversion management in differential pairs to 15 GHz”Electron. Lett., 3rd January 2008 Vol. 44 No. 1

[17]　Matsushima, T.; Watanabe, T.; Toyota, Y.; Koga, R.; Wada, O.,”Prediction of EMI from Two-Channel Differential Signaling System Based on Imbalance Difference Model”,IEEE Electromagnetic Compatibility, pp413-418, 2010

[18]　施政宏,”差模傳輸線在LPC-EBG 結構SI和EMI的影響””國立台灣大學電機工程學系博士論文, 2008.

[19]　Bockelman, D.E.; Eisenstadt, W.R, ”Combined Differential and Common-Mode Scattering Parameters: Theory and Simulation”Transactions on Microwave Theory and Techniques, Vol. 43, NO. 7, July 1995

[20]　張盛富,戴明鳳,”無線通信之射頻被動電路設計”, 2003.

[21]　Spadacini, G.; Pignar, S.A.,”Impact of Common-to-Differential Mode Conversion on Crosstalk in Balanced Twisted Pairs”IEEE Electromagnetic Compatibility, vol.1. ,pp145-150 ,2006

[22]　 J. E. Schutt-Aine, “Time-domain characterization of coupled microstrip
lines,” IEEE Trans. Comp., Hybrids, Manuf. Technol., vol. 15, pp.
231-235, April 1992.

[23]　蔡政憲,”防護線對高速數位信號在板級的電磁干擾影響探討”, 國立交通大學電機與控制學系碩士論文2009

[24] Howard Johnson, Martin Graham,”High-Speed Signal Propagation: Advanced Black Magic”February 24, 2003

[25]　 Ansoft, High Frequency Structure Simulator, Version 11 (www.ansoft.com).