Analysis and Design for Suppressing Edge Radiation of Power/Ground Planes by Decoupling Capacitors

• Main Authors: Kuan-Wei Li, 李冠緯
• Other Authors: 吳瑞北
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/40507721230663164864

碩士 === 國立臺灣大學 === 電信工程學研究所 === 99 === This thesis focuses on the problem of Electromagnetic Interference（EMI）of Printed Circuit Board（PCB）power/ground planes, which is a crucial issue to the whole system stability in the high speed digital circuits. The ground bounce is the primary noise of power/ground planes which arises from the current flowing through a via or the signal trace crossing the slot lines. Bouncing back and forth from the edges of substrate, it will generate a standing wave, and give rise to the radiated emission, usually identified as EMI to the other circuits in the system. The thesis proposed the use of decoupling capacitors around the power/ground planes to suppress the edge radiation noise. A canonical problem simplified from the original structure is constructed, and based on which, the influence of decoupling capacitors on the electric field at the edge is analyzed. Analytical formulae are derived to design the decoupling capacitors with the lowest cost to achieve the best noise suppression. In addition, the analysis predicts the extremely low radiation at a certain frequency, which can be utilized to suppress the most critical noisy spectrum of the system by choosing the suitable capacitance value of decoupling capacitors. Finally, giving the illustrative examples, the design curves and flow charts are presented to facilitate the designers with the practical reference. Full-wave EM simulation and GTEM Cell measurement are used to validate the accuracy of the proposed analysis and design.