Design Techniques for EMC Part 0 — Introduction and Part 1 — Circuit design and choice of components

Eur Ing Keith Armstrong CEng MIEE MIEEE Partner, Cherry Clough Consultants, www.cherryclough.com, Member EMCIA Phone/Fax: +44 (0)1785 660247, Email: keith.armstrong@cherryclough.com This is the first in a series of six articles on basic good-practice electromagnetic compatibility (EMC) techniques in electronic design, to be published during 2006. It is intended for designers of electronic modules, products and equipment. To avoid having to write modules/products/equipment throughout – everything that is the result of a design process will be called a ‘product’. This series is an update of the series first published in the UK EMC Journal in 1999 [1], and includes basic good EMC practices relevant for electronic, PCB and mechanical designers in all applications areas (household, commercial, entertainment, industrial, medical and healthcare, automotive, railway, marine, aerospace, military, etc.). Safety risks caused by electromagnetic interference (EMI) are not covered here, see [2] for more on this issue. These articles deal with the practical issues of what EMC techniques should generally be used and how they should generally be applied. Why they are needed or why they work is not covered, but they are well understood academically and well proven over decades of practice. A good understanding of the basics of EMC is a great benefit in helping to prevent underor over-engineering, but goes beyond the scope of these articles. The techniques covered in these six articles will be: 1) Circuit design (digital, analogue, switch-mode, communications), and choosing components 2) Cables and connectors 3) Filters and transient suppressors 4) Shielding 5) PCB layout (including transmission lines) 6) ESD, surge, electromechanical devices, power factor correction, voltage fluctuations, supply dips and dropouts Many textbooks and articles have been written about all of the above topics, so this magazine article format can do no more than introduce the various issues and point to the most important of the basic good-practice EMC design techniques. References are provided for further study and more in-depth EMC design techniques.