Mitigating the threat of crosstalk and unwanted radiation when using electromagnetic bandgap structures to suppress common mode signal propagation in PCB differential interconnects

Common-mode noise in high-speed differential signaling results in significant signal integrity and EMI concerns. Past work has shown that common-mode filters based on electromagnetic bandgap (EBG) structures can be implemented using standard PCB technology and are effective in suppressing common mode transmission on differential interconnects. This common-mode energy, when filtered, can result in crosstalk or unintentional radiation. In the work described here, the radiation mechanisms in the electromagnetic bandgap structure are examined and a solution involving via stitching and via fences is proposed.