Avoid Routing in Reference Planes

Avoid routing high-speed signals in a reference plane. If it is absolutely necessary, route them over a solid GND reference plane and not across a split plane.

Figure 1. Avoid Route High-Speed Signals across a Split Plane

If you cannot avoid routing over a split plane, place stitching capacitors across the split to provide a return path for the high-frequency current. These stitching capacitors minimize the current loop area and any impedance discontinuity created by crossing the split.

These capacitors should be 1 μF or lower.
Place capacitors as close to the crossing planes as possible.

Figure 2. Use Stitching Capacitors across Split Planes