EMI Suppression Filters (EMC and Noise Suppression)Noise Suppression Basic Course Section 1
Chapter 5 Conductor conduction and common mode

5-4. Summary of Chapter 5

Chapter 5 has described conductor conduction and common mode. This chapter has presented relatively precise explanations for common mode noise, mechanism of its occurrence, and means for prevention.

In terms of noise emission problems of electronic devices, it is very difficult to take measures for common mode noise. Electronic devices are designed to make the loop area of circuit current as small as possible so that the wiring does not work as an antenna for noise. Although it is effective for the normal mode current, it is not so effective of the common mode current. In addition, the common mode noise often flows via floating electrostatic capacitance. It is hard to figure out this capacitance (due to dependence on cable layout) and is difficult to design as a circuit. Furthermore, if common mode noise occurs somewhere in a circuit, the entire system is contaminated via the ground. Such a characteristic is making it difficult to take measures for common mode noise. Common mode noise often occurs from incomplete grounding. It is effective to enforce grounding for reducing common mode noise. Common mode choke coil is effective as an EMC measure component.

[Reference]

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赤尾保男
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[Japanese]電磁妨害波の基本と対策
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Introduction to Electromagnetic Compatibility
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EMI Suppression Filters (EMIFIL ) for AC Power Lines
Murata Manufacturing Co., Ltd. Catalog C09E, 2014

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[Japanese]EMC設計技術 -基礎編-
(社)エレクトロニクス実装学会, 電磁特性技術委員会編 2004

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Investigation of fundamental EMI source mechanisms driving common-mode radiation from printed circuit boards with attached cables
D. M. Hockanson, J. L. Drewniak, T. H. Hubing, T. P. Van Doren, F. Sha, M. J. Wilhelm
IEEE Transaction on Electromagnetic Compatibility, Vol. 38, No. 4, pp. 557-566, November 1996

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PCB Design for Real-World EMI Control
Bruce R. Archambeault
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EMC and the Printed Circuit Boad: Design, Theory, and Layout Made Simple
Mark I. Montrose
Wiley-IEEE Press, 1998

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Noise Reduction Techniques in Electronic Systems Second Edition
Henry W. Ott
John Wiley & Sons, Inc. 1988

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