EMI troubleshooting

Full-wave EMC simulation tools are powerful — but often too slow, too costly, and too complex for real-world troubleshooting. Dr. Min Zhang makes the case for free SPICE-based tools, walking through three field scenarios where quick models helped isolate failures, validate test setups, and guide next-generation designs.

A 140 MHz radiated emissions failure led straight back to a 10 MHz clock — but not the way anyone expected. Near-field probing revealed the real culprit was current, not voltage, doubling the frequency where it mattered most. A practical reminder to measure both when chasing down EMI.

Audio rectification is a common EMI problem in which high-frequency RF signals interfere with low-frequency audio circuits, producing audible noise or distortion. This article explains the causes of audio rectification, demonstrates TDMA/GSM effects on speakers, and offers practical EMI mitigation techniques for designers.

When testing EMI performance, substituting real loads with "equivalent" resistors can mislead you by up to 20dB—enough to turn a passing design into a costly failure. This practical guide demonstrates why fans, motors, and other non-linear loads behave dramatically differently than resistors, and why authentic testing matters for accurate results.