On Tue, Oct 28, 2008 at 02:49:37PM -0400, DJ Delorie wrote: > > > In my 20+ years in engineering I have yet to see one case where > > splitting a ground plane under high-speed ADCs has worked. > > What about high precision ADCs? I'm working on a design using ADE7753 > power monitor chips (16-bit ADCs) , and their own app note (AN564) > shows a ferrite isolating analog ground, and a 10R resistor isolating > AVdd.
In my 30+ years in engineering, I see much more trouble caused by splitting ground planes than solved by them. App notes and example designs are special cases: there is only one chip straddling the analog and digital divide. If you have more than one (e.g., both an ADC and a DAC) all those ideas pretty much go out the window, and you're better off with a single ground plane. I have seen exactly one case where a "split" (very carefully done) on the ground plane was needed to avoid a source of ground return crosstalk. - Larry _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user