I went looking to see if the Analog Device book was available electronically. Here are the links.
Steve Meier High Speed System Applications Table of Contents High Speed System Applications Section 1: High Speed Data Conversion Overview High Speed System Applications Section 2: Optimizing Data Converter Interfaces High Speed System Applications Section 3: DAC, DDS, PLL's, and Clock Distribution High Speed System Applications Section 4: PC Board Layout and Design Tools On Tue, 2008-10-28 at 13:44 -0700, Steve Meier wrote: > I won't argue this point. I will refer every one to an Analog Device > publication "High Speed System Applications" copyright 2006 ISBN-10: > 1-56619-909-3 or ISBN-13: 978-1-56619-909-4 > > In particular if you get a copy of this book (and they gave me mine) > look at pages 4.15 and 4.16 > > There AD recommends connecting both of the A/D grounds "digital" and > "analog" to the analog ground plane "this is because it causes less > problems for the relatively small amount of digital return current to be > returned through the analog ground than it would to connect the > converter to the much noisy digital ground. > > There is a lot more talked about then just that one blurb. > > Steve Meier > > > > On Tue, 2008-10-28 at 11:22 -0700, Joerg wrote: > > Stefan Salewski wrote: > > > Sometimes it is necessary/recommended to partition (separate) power or > > > ground planes, i.e. for ADC or DC/DC-Converters, see page 16 and 17 in > > > > > > http://focus.ti.com/lit/ug/slwu028c/slwu028c.pdf > > > > > > We can do this in pcb program with (adjoining) polygons. > > > Disadvantage is, that if we change the size of one of the polygons we > > > have to manually adjust the other sizes. A other method may be so divide > > > a large polygon by copper clearing traces (with trace width zero). > > > > > > This is related to my question from > > > > > > http://archives.seul.org/geda/user/Sep-2008/msg00387.html > > > > > > but not identical. > > > > > > What is the best way to handle this? > > > > > > > I can't speak to that but just one word of caution: In my 20+ years in > > engineering I have yet to see one case where splitting a ground plane > > under high-speed ADCs has worked. Regardless of what application notes > > say. Usually it didn't work, lots of noise. Or it kind of worked but > > fell apart the instant somebody whipped out a GSM cell phone or BlackBerry. > > > > Myself, I never spilt a ground place. OTOH the industry practice of > > splitting planes is providing part of my income :-) > > > > The only time I split is where required for safety, for example patient > > isolation per 60601 (ECG, ultrasound etc.). > > > > > > _______________________________________________ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user