Oakley Re: [sdiy] analog or digital ground?

[Cynthia Webster]

Hi!

The best information That I've found about isolating these grounds
is at Tony Allgood's Oakley Synthesizer website

http://www.oakleysound.com/

he really explains it quite thoroughly!

Hope this helps

Cynthia


> on 11/10/02 3:15 PM, Trevor Page at t at introspectiv.org wrote:

> Seb,
> 
> An interesting question this, for which I'm sure many will offer a much
> better answer than I can. My thoughts are, however, that the MUX GND
> terminal will itself be 'noisy' due to the internal logic decoder/driver
> circuitry, and therefore should be kept well away from the analogue
> ground for starters. I also expect that there will be a high degree of
> isolation between the GND (together with associated noise) and analogue
> signals with a good MUX chip, so I'd feel safer using the digital
> ground. Either that, or give the MUX a separate ground track back to
> star ground maybe?
> 
> Trev
> 
> 
> . .  .   .    .     .
> t at introspectiv.org
> http://introspectiv.org/
> 
> 
> 
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Seb Francis
> Sent: 10 November 2002 21:25
> To: synth diy
> Subject: [sdiy] analog or digital ground?
> 
> 
> 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
> 
> 
> 
> 
>