Let me clarify.....
Howard Johnson has described a "ground Plane" effect where the high
speed signal tends to travel on the surface of the plane closest to the
trace.
The skin effect is a matter of current density. In the skin effect case,
the current density is higher along the edge of the trace and lower in
the middle of the trace. The ground plane (or proximity) effect means
that the current density will be higher on the surface closer to the
other conducting surface.
What I was looking for is this: Is the current density higher on both
the top AND bottom surfaces of the plane, and lower at the midpoint of
the plane. OR... is it highest on the top surface and it declines down
to the opposite surface?
Doug
Ben Jordan wrote:
Is this some kind of trick question? Skin effect exists in any conductor
carrying AC. Including GND. In fact, why not just call the trace ground and
the plane the signal... isn't it all relative? ;-)
Curious to hear your response...
On Fri, Dec 6, 2019 at 10:34 AM Doug Brooks <dbrooks9@xxxxxxxxxxxxxxx>
wrote:
We all know what the skin effect is on a trace. And we all know the
return signal path is on the plane directly under the trace.
The question is, is there a corresponding skin effect on the ground plane?
Doug Brooks
--
*************************************************************
See Doug's latest books, available on Amazon. "PCB Trace and
Via Currents and temperatures; The Complete Analysis,
2nd Edition." and "PCB Trace Current/Temperature Curves,
0.25 Oz. to 5.0 Oz., The Complete Set."
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