Whitepaper explains how to design cost-effective EMC filtering

06 June 2018

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Choosing the right filter for an application is considered by many design and electrical engineers to be something of a dark art. Fortunately, help is at hand – a new whitepaper from EMC Standards. The whitepaper provides design engineers with a guide to designing the right filters for their products, and is available for download in the member’s area of the EMC Standards website.

The whitepaper, by global EMC specialist Keith Armstrong, offers guidance on choosing the correct specifications and style of a filter. Armstrong states that the guidance is akin to taking “anti-Murphy” precautions – referring to the adage that “anything that can go wrong will go wrong”. The advice aims to pre-empt Murphy’s Law from affecting filters, through better specification in the design process.

Correct filter specification is critical in ensuring the rest of the design process is completed with minimal project cost, with the remainder of the process often being a matter of trialling different filters and measuring emissions and/or immunity.

Armstrong also offers a range of tips to help engineers improve the effectiveness of their designs. One such tip is for engineers to understand that filtering and shielding should be designed together, because neither will achieve anything like their full performance, without the other being designed correctly. Another tip is that the full specification of a filter will not be achieved without careful design of its assembly in the product.

Keith Armstrong explains: “EMC filtering is a gripe of many electrical and electronics design engineers. This is because it’s difficult to accurately predict the performance a filter will deliver when installed in a product, which means that experimenting with different filters is often necessary. Good initial design and specification ensures that this experimentation stage does not cause unacceptable delays in the product entering the market and does not significantly increase production costs.

“With this whitepaper, engineers can get a greater understanding of the importance of proper filter specification at the right time in the design process. I also provide a brief overview of other factors to consider, such as RF shielding and the often-optimistic impedance specifications of filters, to help ensure safe and reliable products can be designed more quickly and cost-effectively.”

The whitepaper is available for download for members of the EMC Standards website. Engineers interested in accessing the whitepaper and a wealth of other EMC resources and cost-effective courses can do so by registering with EMC Standards. Go to for further information.

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