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The best way to address (or prevent) EMI issues is at their source.
As electronic designers, we should view EMI problems as challenges related to containing electromagnetic fields.
This means there are several things I need to ensure before sending my project for production, or if it’s already failing an EMC test.
One of the most critical factors is keeping the signal’s reference as electrically close as possible to the signal conductor.
This must be maintained not only during horizontal propagation (along traces) but also during vertical propagation (when the signal transitions between layers through vias).
Another key point to consider is the impedance the signal encounters throughout its entire path.
Think of impedance as the ratio of voltage to current.
If this changes, the signal’s characteristics change too, and that’s something we want to avoid.
A shift in impedance can lead to signal reflections or even convert the signal from differential-mode propagation to common-mode propagation.
When this happens, you’re in trouble.
Common-mode currents are highly efficient at generating emissions, which can quickly turn into major EMC headaches.
Hope this helps.
-Dario
P.S. Want to dive deeper into mastering these EMC strategies?
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