PCB Inductor With Integrated Shielding to Contain Switching Electric Field and Reduce CM Noise

Abstract

Continued improvements in power semiconductor technology have allowed power supplies to become increasingly miniaturized and integrated. However, care must be taken to ensure the converter's switching noise does not interfere with its sensing circuitry, gate drivers, or electromagnetic interference (EMI) filter. Prior works have shown how switching noise can capacitively couple to the EMI filter and significantly increase conducted common mode (CM) noise. This article aims to contain the switching electric field of a front-end power factor correction (PFC) converter by integrating conductive shielding around the switches and PCB-winding inductor. A novel planar inductor structure is proposed to shield the inductor's electric field without adding significant eddy losses. The proposed shielding effectively contains the switching electric field of a GaN-based totem-pole PFC converter, which reduces its CM noise up to 28 dB with minimal impact on converter loss ( $\Delta \eta$ = 0.06%). A detailed design procedure is provided for the proposed inductor shielding based on parametric studies with 3-D finite element analysis (FEA) simulation tools.