The application of multi-stage EMI filter design method in planar EMI filter

The planar EMI filter has great engineering significance to power electronic systems integration and miniaturization. However, for some special occasion like the EMI noise is serious, the single-stage EMI filter can not meet the demand of noise suppression, and the multi-stage EMI filter is an important choice to solve this trouble at this time. This paper proposes a design method of multi-stage EMI filters. The two-stage EMI filter topology is taken as an example to introduce the method of using the voltage attenuation (G) instead of insertion loss (IL) to evaluate the effect of EMI filter. To reduce the volume of multi-stage EMI filter, the application of multi-stage EMI filter design method in planar EMI filter is presented. Finally, the differences between the passive discrete EMI filter and planar EMI filter are pointed out, and the matters needing attention in designing multi-stage planar EMI filter is given.