Study on Radiated Emission Factors and Their Effects in a Boost Switched Mode Power Supply

The physical radiated emission sources and main radiated structures of a Boost converter are identified according to equivalent radiation antenna in this paper. The turn-off voltage of MOSFET and the recovery current of diode are found as the sources for their oscillation frequencies are coincidence with radiation curve measured. The influence of the converter's metal enclosure is analyzed on two aspects, its role on main circuit working state and its change on radiation structure. CST circuit simulation and far field calculation tools are adapted to validate above analyses. Low impedance grounding and CM choke methods are used to restrain the radiated emission of this converter in the end.