ElEctric_EyE wrote:
Garth, I interpreted your 'jagged' comment to mean diagonal so I tried to come up with a better layout:
I'm not sure what you mean by 'jagged' unless you're referring to the term "chainsaw" which just means there are cuts (regardless of shape) in what otherwise looks like a plane layer, in this case a power plane. As long as this layer doesn't get between your signal traces and the continuous ground plane, you'll be fine. Remember that any given signal trace's return current through the plane tries to run directly under that trace, taking the shape of the trace, but that if there's a cut in the trace, the return current has to take a different path and you end up with what amounts to an inductor or a stub depending on the length and width of the cut, and it degrades signal integrity. Actually, sometimes a cut in the plane, running perpendicular to the trace, is intentionally used to print an antenna on the board, something you don't want in this case. I really have no way of evaluating the effects for the particular application, so, since you're dealing with sub-nanosecond rise times for the fast, hi-res video stuff, I just shoot for next best, which we give the nebulous term "good engineering practice."