by Timothy Hegarty, Texas Instruments, Phoenix, Ariz., How2Power Today, Aug 14 2020
Focus:
EMI modeling usually involves the characterization of noise sources and the essential coupling
paths, and these models can be physics-based or behavioral models. The latter enable faster and
more stable simulations. Part 14 of this series provides an introduction to and overview of
behavioral EMI models, where a compact association of noise sources and impedances identifies
the dc-dc converter and its external EMI behavior. This article will discuss two types of
behavioral models—two-terminal (one-port), decoupling-mode models and three-terminal (two-port)
models. Since the latter type provides greater accuracy, details on how to extract parameters
for the three-terminal models will be presented. There are two methods for extracting these
parameters—one involves taking measurements across the converter’s input terminals with shunt
impedances attached and power applied to the converter, the other involves measurement of
converter input impedances with power removed. Both methods will be described
here. The article concludes by comparing DM and CM noise predictions obtained for a three-
terminal model of a 50-W buck converter with bench measurements.
What you’ll learn:
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