Research on Suppression Method of EMI Signal

In order to obtain higher insertion loss of the EMI filter in the frequency range of 0.15 to 30 MHz, and achieve the largest attenuation EMI signals, the insertion loss expression of impedance dismatch is deduced according to the basic definition of EMI filter insertion loss. And the impacts of EMI insertion loss and reflected loss resulted from impedance dismatch is analysed. The total principles of designing and choosing EMI filter structures are presented to diminish the impacts of impedance dismatch. It is verified by the experimental results. These conclusions are useful to the design and choosing of EM filter.