Improving the high-frequency performance of integrated EMI filter with multiple ground layers

In this paper, a novel structural winding arrangement is proposed to improve the high-frequency characteristics of the integrated EMI filter. Two ground winding layers are introduced to couple with common-mode (CM) choke winding to implement the CM capacitors so that the common mode EMI filter becomes a two-stage filter. Simulated by the Finite Element Analyze (FEA) software, the second resonance peak of transmission gain brought by the equivalent series inductance (ESL) is sharply decreased compared to the original structure to improve the high-frequency performance. In order to better analyze the proposed structure, the structural winding capacitance model of the planar spiral winding structure is given and the equivalent circuit is derived. Simulated and experimental results are included and they confirm the filtering effectiveness of the integrated planar EMI filter.