[sdiy] analog or digital ground?

[Seb Francis]

Hi,

I'm just routing the PCB for my MIDI2CV, and I've been pondering which ground plane to connect the S&H MUX to.

It's a MAX306 (+/-V supply and analog signal range, TTL/CMOS compatible digital inputs).  Digital inputs come direct from a PIC (so they're pretty noisy).

My first thought was to wire the GND pin to the digital ground (assuming there might be a bit of coupling to ground from the digital inputs), but the datasheet doesn't give much clue whether GND is in any way internally connected with the analog signal - the digital ground plane is itself a source of noise.

Any thoughts?

Seb