Wideband Suppression of Radiated Emissions from a Power Bus in High-Speed Printed Circuit Boards

We present experimental demonstrations of electromagnetic bandgap (EBG) structures for the wideband suppression of radiated emissions from a power bus in high-speed printed circuit boards (PCBs). In most of the PCB designs, a parallel plate waveguide (PPW) structure is employed for a power bus. This structure significantly produces the wideband-radiated emissions resulting from parallel plate modes. To suppress the parallel plate modes in the wideband frequency range, the power buses based on the electromagnetic bandgap structure with a defected ground structure (DGS) are presented. DGSs are applied to a metal plane that is connected to a rectangular EBG patch by using a via structure. The use of the DGS increases the characteristic impedance value of a unit cell, thereby substantially improving the suppression bandwidth of the radiated emissions. It is experimentally demonstrated that the DGS–EBG structure significantly mitigates the radiated emissions over the frequency range of 0.5 GHz to 2 GHz as compared to the PPW.