Dispersion Analysis and Design of Planar Electromagnetic Bandgap Ground Plane for Broadband Common-Mode Suppression

A planar electromagnetic bandgap (EBG) structure designed for broadband common-mode suppression is proposed. A uniplanar compact photonic-bandgap (UC-PBG) structure with periodic center slots is etched on the ground plane to obtain broadband common mode suppression while minimally disturbing the differential signal within the designed bandwidth. Dispersion analysis has been conducted for both common (even) and differential (odd) mode signals. Good signal integrity is observed in both simulated and measured results. The fractional bandwidth of the proposed EBG ground plane is around 70% with common-mode suppression below -20 dB. The proposed EBG ground planes may be applicable for systems requiring low-cost and simple solutions in designing high-speed differential interlinks operating above 5 Gbps.