[sdiy] Ground planes for mixed signal designs - to split or not to split

[Seb Francis]

Thank you Eric & Peter for your replies about this.

I've taken the plunge and redone the schematic with a single ground, and 
the PCB layout with a single ground plane.  Have just finished routing 
it and as it turns out the digital routing is so dense that it almost 
completely cuts the ground plane on the digital side from the analog 
side.  So I just added an extra cut to ensure no digital ground current 
flows through the analog zone, and a small no-plane area to ensure 
digital traces aren't running opposite the analog zone ground plane.

So I've kind of ended up with a split ground plane after all, but it's 
connected on the PCB so at least I know any inductance / potential 
difference between the 2 sides is going to be reasonably small.

I please that I managed to fit in a 4 channel DAC and buffer for CV 
outs, and keep the board 98x105mm to ensure compatibility will all types 
of modular cases.

Approx 2x actual size when viewed on a 96dpi monitor..
http://burnit.co.uk/sdiy/stuff/top.png
http://burnit.co.uk/sdiy/stuff/bottom.png

Thanks for all the help from the list so far .. can't wait to get it 
made & soldered up and get on with the software :)

Seb