Troubleshooting EMI Issues Caused by Structural Resonances

Most EMI issues are caused by a resonance that is excited somewhere in the system. It may be a resonance of a cable acting as an antenna or a heatsink energized by the power electronics switches bolted to it, becoming a good radiator. In this article, we look at the indicators that signal the presence of structural resonances and provide techniques for fixing the EMI issues. Practical case studies are presented to demonstrate the techniques.

Use of Ferrites in PCB Reference Planes

Should the reference (i.e., ground) plane be split into two separate sections and a ferrite bead installed between them to prevent unwanted radio frequency emissions? Let’s examine why this practice is not a good idea and should be avoided at all costs.

PCB Return-Current Distribution in a Microstrip Line

This article discusses the distribution of a PCB return current underneath top trace for the microstrip configuration. Next month’s article will discuss the distribution for the stripline configurations.
article placeholder

Avoid Critical Signals in Edges of the PCB

When routing a printed circuit board (PCB), try to avoid critical signals in emissions or immunity close to the edge of the board to create a more robust system for EMI and EMC.