Often stupid partitioning of GND in digital and analog can generate
much
trouble, so one single low impedance ground plane can be a simple and
not too bad solution.
Yep. But a single plane *may* lead to stray currents flowing near
sensitive analog stuff, like
ADC and DAC. I don't want to degrade the performance of these parts.
In fact, my analog gnd
plane is sectioned as well, in order to isolate the high-current section
from the low signal portion.
Now that it's not 2 AM, and maybe I'm thinking a little more clearly,
the ADC and DAC can
be contained in one area, where the digital and analog gnd plane
connects. Don't know
why I didn't think of that before - that takes care of most of the high
speed digital signals that
transition between the two domains. That leaves some others, like I2C
and pseudo-static
control lines, which I am at a loss on the best routing methodology.
Good luck with your design. The addage "follow the currents" works
pretty well in figuring
out if you will have trouble. Sort of like pretending your the
electron, and see where you go.
gene
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