[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: gEDA-user: analog/digital partitioning



On 07/22/2010 09:57 AM, Steven Michalske wrote:
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. :-)

Good point - that's left as an exercise for the engineer. In my case these were 16-bit DAC data buses running at 250MHz, so a few extra inches in the return path could cause some noticeable distortion in the higher harmonics and splatter the edges.

OTOH, this board has a 5-bit async attenuator control bus that pops about once an hour and we didn't give those any priority.

Eric


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user