Bypass cap's

[jhaible]

> Ironically, some digital circuits built on power/ground plane boards need
no
> bypass
> caps at all.  I was informed that the stored energy exists due to the
> topology of
> the planes.  Something about the "H" field, but I'm no expert in these
> matters, so
> perhaps a lurking physicist may care to comment.

Make that "E-Field", and it makes sense.
C = epsilon * A / d,
epsilon being the dielectric constant of the PCB material,
A being the area, and d being the distance between the planes.
This only makes sense when you have two planes in close
proximity - surely not with the 1mm or more of a double sided board.

JH.