A New, Low-Cost Common Mode RFI Suppression Technique for Switch Mode Power Supplies

This paper presents a new method to attenuate common-mode conducted radio frequency interference (RFI) fed back onto the ac power input leads of a high-frequency switching power supply. The technique uses a circuit to cancel the effect of the noise-generating sources. This method is also effective for reducing common mode noise on the output leads. The benefits and effectiveness of this low-cost RFI suppression technique are discussed.