Re: gEDA-user: analog/digital partitioning

[Steven Michalske <smichalske@xxxxxxxxx>]

On Jul 22, 2010, at 9:50 AM, Eric Brombaugh <ebrombaugh1@xxxxxxx> wrote:

> On 07/22/2010 09:37 AM, DJ Delorie wrote:
>> 
>> One idea to consider is to start with a solid plane, and cut slots
>> around the sensitive analog parts, like big C shaped moats, squares
>> open on one side.  You retain the "big ground plane" conductivity, but
>> you prevent stray currents from using your analog area as a short-cut.
>> 
>> Each analog "chunk" can have it's own moat this way, too.  If they're
>> near the edge, just cut a thin slot from the edge in.
> 
> I've used this approach on some relatively high-speed digital/analog/RF boards. Seems to work pretty well.
> 
> Just make sure that if you've got high-speed digital lines that cross into the 'cubicles' they have gnd plane underneath them where they enter - don't let fast signals cross the cuts because then the return currents have to take a different path and that will screw up the signal integrity.
> 
The question is "how fast?". Because you loops may not even matter.  But just remember to keep them small. :-)


> Eric
> 
> 
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