EMC Design In Practice - Conducted Emissions
Categories: EMI - Short Post
One of the final tests for your electronic design before it becomes available on the market will be the conducted emissions test.
Although many factors will influence the test's outcome, one of the most critical factors that will have the greatest impact is the wiring layout of the system, particularly the Printed Circuit (PC) layout of the board.
Here are some of the factors determining the board's performance:
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Board partitioning into separate sections (Not separate return reference planes!)
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Poor stackup choices (Not designed with Electromagnetic fields and return currents in mind)
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Crosstalk between signals, including ground bounce (Not considering fields and proximity)
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Poor component placement (Resulting in large current loops, significant trace inductance between decoupling capacitors, and so forth)
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Impedance Discontinuities (Not considering Impedance, its role, and reflections)
And the list goes on...
All of these factors can easily lead to unwanted signal coupling to the power cords.
Before you know it, these unwanted signals sneak their way into the power distribution network and radiate!
The next time you're routing your PCB, keep these factors in mind.
I hope this helps,
Dario