Technology of splitting PCB conductors to weaken the parasitic parameters for planar EMI filter

EMI filter has been more and more attention because of its suppression of the effectiveness of the conducted EMI in switching power supply. Compared to the filter of discrete components, planar EMI filter has the advantages of small size and high-frequency performance. However, the inductance of the equivalent parallel capacitance (EPC) and equivalent series resistance (ESR) of such filters has its special requirements. Based on the basic principles of the EMI filter, the affect of the PCB conductor cross-section design of the common mode inductor performance is analyzed in this paper; Under the conditions of the existing technology, a kind of planar integrated LC unit based on split parallel structure is proposed and the EPC and ESR of common-mode inductance of split parallel structure of LC unit is analyzed. Some corresponding experiments are done and the result is compared with single-stranded structure.