Optimization calculation of the common mode insertion loss of EMI filters under impedance-mismatch conditions

To consider the optimization calculation of the common mode Insertion loss of EMI filters under impedance-mismatch Conditions, the effects of the source and load impedances on the insertion loss of filters are analyzed in detail. A method to calculate the minimum insertion loss of electromagnetic interference (EMI) filters under impedance-mismatch conditions is presented. The result indicates that the parasitic capacitance and parasitic inductance cause deviation of insertion loss measurements from theoretical calculation results in high frequency. The model of a typical kind of EMI filter is modified by optimization method. Finally, the modified model in high frequency and the method to calculate the minimum insertion loss is verified to be valid.