Routing differential I/O signals across split ground planes at the connector for EMI control

Abstract

Routing single-ended signals across split ground and power planes disturb the return currents that normally flow adjacent to the signal trace, creating high common mode currents, increase crosstalk between adjacent traces that are routed across the split, and distortions in the signal wave shape (signal integrity). For differential signals, however, the normal mode signal return currents flow on an adjacent trace, rather than through the ground plane, minimizing the impact of the split plane.