Webinar: 7 habits to successfully pass EMC by Kenneth Wyatt

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Join us on February 7th for a webinar with @ken!

You can already post your questions in this thread.

What about the GND return vias near to the high-speed signal vias? is it worth it?

If the return path of the high-speed signal is changing planes, then you definitely need a via connecting those planes. If the signal is just changing from one side of the return plane to the other, adding a ground via won’t help.

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thanks for your answer, this helps a lot.

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What are the general filtering practices one should follow for filtering out the IO/Connector that are going out of the board? For our application, We have long cables connecting multiple PCBs and these cables carry power and signals that are switching. We are seeing good amount of radiation as there is no filtering present at the moment.

I wasn’t able to make the time slot. Is there a recording I can watch? Thanks!

Yes, I’ll send tomorrow.

Placing one (or two!) stitching vias (connecting two return planes) or a decoupling capacitor (if penetrating through return and power planes) is always a good idea for high speed digital signals.

In that case, it’s always best to filter at the source. For high speed digital signals (differential mode currents) the best bet is to ensure an adjacent solid return plane to minimize the loop area.

If the issue is common mode currents being generated on the board, the best technique is to eliminate or reduce the generation of these currents through proper PC board and circuit design. To filter common mode currents requires common mode chokes located as near as possible to the I/O or power connector. Additional differential mode filtering may also be required.