Design and implementation of planar EMI filter under the condition of impedance mismatching

A novel integration structure of EMI filter based on multilayer ceramic is proposed in this paper. The inductors and capacitors of the new structure can be designed separately, which is advantageous to manufacture. Besides, the Insertion Loss(IL) is usually measured under the condition of the source impedance and load impedance are both 50Ω, which is different from the actual situation. In the process of design novel EMI filter, the noise impedance is taken into consideration in this paper. And, the prototype is made and applied to the 100w switching power supply. The effectiveness of the developed EMI filter is verified.