A review of EMI problems in switch mode power supply design

Switch mode power supplies (SMPSs) have rapidly gained popularity in recent years because of their high-efficiency and relatively small size and weight. Although SMPSs may not be operated at a very high frequency, the associated square pulses are full of high frequency components that may cause electromagnetic interference (EMI) to other electronic products. Methods have been derived to reduce interference, such as snubbering, filtering and spreading switching spectrum. This article gives a review on the various aspects of EMI problems related to the design of SMPSs and in particular discusses the sources and victims of interference and some controlling methods.