PC Board Design for Low EMI

by Kenneth Wyatt

As a consultant for over 10 years, I’ve had a chance to perform design reviews or help troubleshoot hundreds of products. In so doing, I’ve realized the root cause of many design issues revolves around the circuit board design. Poor board designs can result in radiated emissions, radiated immunity, and electrostatic discharge (ESD) compliance failures, among others. Bad board designs often result in endless cycles of trial and error mitigation - compliance testing - board spins - and more troubleshooting/mitigation/spins. This drags out the schedule and is very costly.

I’ll explain why reducing circuit loop areas is only part of the solution and to understand proper board design for lowest EMI requires understanding how signals propagate in boards. Once you understand signals move via electromagnetic fields, then board stack-up and trace routing should become very clear and you should be able to design a low-EMI board the first time!

Kenneth Wyatt, Wyatt Technical Services LLC