1. Introduction – why a small change can make great differences in the plot Did this happen to you. You go to the testing lab. you do a full RE scan and the scan looks great. Then you Rotate the EUT 90° Lift a cable Move the EUT by 20 cm Change cable routing And the emissions plot changes. This is not randomness. It is physics. Radiated EMC measurements are strongly influenced by how the product couples to its environment. I want to discuss this today, so, next time, when you are in a chambe...

When I debug EMC problems on a DC/DC converter, I use a very simple test to understand whether the dominant mechanism is Differential Mode (DM)  or Common Mode (CM) . The test is simple: I increase the load and observe what happens to the emissions. If: The peak frequencies stay the same, But the amplitude increases with load, then the behaviour is consistent with differential-mode emissions . This is aligned with what TI explains in their EMI material: Differential-mode noise increases with...

Introduction In switch‑mode DC‑DC converters, not all currents are equal from an EMC, signal integrity, or reliability perspective. A critical distinction must be made between low di/dt current paths  and high di/dt current paths . Misidentifying these paths is one of the most common root causes of excessive EMI, poor efficiency, unstable switching behaviour, and failed compliance tests. This article focuses on: How to correctly identify high di/dt and low di/dt current loops in DC‑DC...