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.). -- Regards, Joerg http://www.analogconsultants.com/ _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user