Prediction of Far-Field EMI from Printed Circuit Boards by Means of Near-Field Measurement

通过近场测量预测印刷电路板的远场 EMI

• 批准号: 11834008
• 负责人: WADA Osami
• 金额: $ 2.24万
• 依托单位: Okayama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11834008/
• 关键词: printed circuit board; near-field measurement; EMI; EMC; far-field; bus line; clock line; simulation

This research is to investigate prediction of far-field EMI (Electro-Magnetic Interference) from printed circuit board (PCB) by means of near-field measurement. Particularly, radiated emission from "bus lines" and "clock lines" on a high-speed digital PCB has been investigated.First, radiated emission from a single clock line with a finite ground plane is measures in far field. Each of the test boards has rectangular cuts on a ground plane, and ground width of a return path just under the clock line is altered. Radiated emission from the test boards is evaluated at a 3m distance from the board in a semi-anechoic room, and the corresponding common-mode current for each test line is also measured. As a result, common mode current and corresponding emission are theoretically predicted that are caused by the difference of unbalance factors of transmission lines. Reduction of common-mode current and emission due to the decrease of ground inductance agrees well with the theory. The results explains required width of the return path on a PCB ground, which can be used in practical design of digital printed circuits.Next, periodical and random signals on bus lines are investigated. Timing control of signals is proposed for the reduction of EMI, and it is examined with a pair of signal lines. The EMI reduction effect for both of PCBs with wide and narrow ground planes is explained with theoretical calculation and measurements. The technique is also effective for reduction of the common-mode current, near-field and far-field EMI.

本研究旨在探讨利用近场量测预测印刷电路板之远场电磁干扰。特别地，本文研究了高速数字PCB上的总线和时钟线的辐射发射。首先，在远场测量了具有有限接地层的单条时钟线的辐射发射。每个测试板在接地平面上具有矩形切口，并且改变时钟线正下方的返回路径的接地宽度。测试板的辐射发射在半消声室中距离板3 m处进行评估，并测量每条测试线的相应共模电流。从理论上预测了由于传输线不平衡系数的不同而引起的共模电流和相应的发射。由于接地电感的减小，共模电流和发射的减小与理论一致。该结果解释了PCB接地回路所需的宽度，可用于数字印刷电路的实际设计。其次，研究了总线上的周期性和随机性信号。为了减少电磁干扰，提出了信号的定时控制，并用一对信号线进行了检验。通过理论计算和测量，说明了宽接地面和窄接地面对PCB板的EMI抑制效果。该技术对减小共模电流、近场和远场电磁干扰也是有效的。

项目成果

Wada,Takahata,Toyota, et al. (第1筆者 : Osami Wada): "Power Current Model of Digital IC with Internal Impedance for Power Decoupling Simulation"Proceedings of 4th European Symposium on Electromagnetic Compatibility. Vol.2. 315-320 (2000)

Wada、Takahata、Toyota 等人（第一作者：Osami Wada）：“用于功率去耦仿真的数字 IC 的功率电流模型”第四届欧洲电磁兼容性研讨会论文集（2000 年）。 ）

Watanabe, Wada, Koga (第1著者:Tetsushi Watanabe): "Common Mode Current Prediction from Normal Mode Voltage with Limited Width Ground Pattern of Printed Circuit Board"1999 International Symposium on Electromagnetic Compatibility. 220-223 (1999)

Watanabe、Wada、Koga（第一作者：Tetsushi Watanabe）：“根据印刷电路板有限宽度接地图案的常模电压进行共模电流预测”1999 年国际电磁兼容性研讨会 220-223（1999 年）。

Watanabe, Wada,Miyashita, Koga (第1著者:Tetsushi Watanabe): "Common-Mode-Current Generation Caused by Difference of Unbalance of Transmission Lines on a Printed Circuit Board with Narrow Ground Pattern"IEICE Trans. Communications. E83-B・3(印刷中). (2000)

渡边、和田、宫下、古贺（第一作者：渡边哲志）：“窄接地图案印刷电路板上传输线不平衡差异引起的共模电流产生”IEICE Trans.3。 （正在出版）。

Wang, Wada, Takahata, Koga (第1筆者: Zhi Liang Wang): "Reducing Q-factors of Resonances in Power/Ground Planes of Multilayer PCBs by Using Resistive Metallic Layers"Proceedings of the 2000 Japan-China Joint Meeting on Optical Fiber Science and Electromagneti

Wang, Wada, Takahata, Koga（第一作者：王志良）：“Reducing Q-factors of Resonances in Power/Ground Planes of Multilayer PCBs by Usesive Resistive Metallic Layers”2000年中日光纤科学联席会议论文集和电磁

Wang,Wada,Toyota,Koga (第1筆者 : Zhi Liang Wang): "An Improved Closed-Form Expression for Accurate and Rapid Calculation of Power/Ground Plane Impedance in Multilayer PCBs"Proceedings of Symposium on Electromagnetic Theory. EMT-00-68. 17-23 (2000)

Wang, Wada, Toyota, Koga（第一作者：Zhi Liang Wang）：“一种改进的用于准确快速计算多层 PCB 中电源/接地平面阻抗的闭式表达式”EMT-00-68 电磁理论研讨会论文集。 17-23（2000）