高速數位系統的印刷電路板電磁相容分析

EMC Analysis on the PCB of High-Speed Digital Systems

邱建文(Chien-Wen Chiu)

《國立宜蘭大學工程學刊》 1期 (2005/02) Pp. 1-13

https://doi.org/10.6176/BCE.2005.01.11

摘要

資訊產品的硬體系統為因應多個電源電壓需求，印刷電路板層結構的金屬電源平面或接地平面經常被切割成為有限寬度平面；另外，由於數位訊號操作的時脈速度也逐漸提高，因此電磁相容（EMC）及干擾（EMI）問題逐漸嚴重。本論文的研究重點在於了解有限寬度電源或接地金屬平面的PCB結構，在包含非線性元件於高速傳輸下的EMI機制及影響。實驗設計上，製作高速時脈驅動的PCB電路板進行三米輻射場量測以了解輻射效應外，並考慮不同位置電源饋入所造成輻射場的改變。在理論方面，則以時域有限差分法（FDTD）進行模擬，以了解在處理此類PCB之EMI問題學理上的可行性。理論模擬上首先考慮有切割槽縫的金屬平面所造成的接地反彈（ground bounce）問題，然後再模擬利用差動訊號傳輸來連接主動元件，以降低不完整金屬平面所造成共模訊號輻射時的影響。

關鍵字

電磁干擾 ； 電磁相容 ； 時域有限差分法 ； 接地反彈

並列摘要

As clock speed is gradually increased, the EMC problems on the practical printed circuit board become more serious and sophisticated due to the demands of different power level or ground plane slitting. This paper will be emphasized on characterizing the radiation mechanism of PCB with imperfect ground and nonlinear load. A typical PCB structure with three layers and high-speed clock driver was designed and fabricated to investigate radiated electromagnetic field. Measurement was performed at an anechoic chamber room and E-field was measured at 3m away. By applying the FDTD approach, simulation program was established to validate its feasibility to solve the EMI problem of PCB in the high-speed digital systems with slit ground plane. Transmission line with differential signals will be recommended and demonstrated to reduce the common-mode radiation field as nonlinear driver or receiver is connected to the imperfect ground plane.

並列關鍵字

EMI ； EMC ； FDTD ； SPICE