Efficient EMI reduction in multilayer PCB using novel wideband electromagnetic bandgap structures

Electromagnetic interference is a significant problem in high-speed circuits. To minimize its effect and improve the electrical characteristics of circuits such as signal integrity and electromagnetic compatibility, the application of an electromagnetic isolation structure with electromagnetic bandgap (EBG) is considered. In this paper, a novel wideband EBG structure is proposed for EMI reduction in multilayer printed circuit boards (PCB), in which a kind of improved L-bridge is used as additional series inductance, and the equivalent inductance can be increased significantly. Compared to the traditional mushroom-liked EBG structure with the same parameters, the L-bridge structure can broaden the relative bandwidth to nearly 250%, with a significant decline of the center frequency. The effectiveness and accuracy of this structure are verified by both simulations and measurements.