Man, you guys are taking me to town on this one.
Not that I mind.  I just don't want to be the only
one squawking here. :)

---> Nothing but a 4-layer board <---

I would follow one of the rules about avoiding at
all costs slicing up the ground plane.  It doesn't
say anything about the power plane.  Again, this
is a hypothetical case, so I personally would reduce
the size of the power plane as much as possible.
Better to leave intact as much ground plane as you
can and reduce only the size of the power plane to
the specific areas that need it.  But you have to
be careful doing that for you can really screw things
up.

---> Nothing but a double-sided board <---
Carry the above thought to a single layer board and
justify every single trace, placement of parts,
partitioning of circuits, use passive gnd traces as
a gnd reference for controlled impedance traces, etc ...

I don't want to put on the wrong impression here.
Personally, I'd have difficulty doing a high-speed
mixed family double-sided board single-layer board.

I have seen it done.  And I know that there have
got to be some real artists out there.  But, I
think, unless given a lot of time and resources,
a high speed single layer board is just about
at my limit.

Doug

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