piclist 1998\10\26\120209a >
Thread: Crystal Tutorial
face BY : Dave VanHorn email (remove spam text)

If this is achieved, circuit power
> consumption will be minimized, and so will EMI emissions
> (since the two caps will be trying to feed roughly equal
> and opposite currents through their ground returns).

That's an interesting note indeed. I'm sure that the phase will be 180
out, but I'm not sure the amplitude will be the same, so they may not
cancel entirely.

> The biggest question I'd still have, then, would be how to
> select the best value for the caps from among all those that
> produce the perfect 180 degree phase shift.  Would the ideal
> value be one where the ratio of the caps roughly matched the
> ratio of the signal strengths (so as to best balance out the
> ground currents)?

The xtal is cut for a specific loading cap value. Start a bit less than
that, allowing for the stray C on the board.

<3634AA88.6EA0B87D@cedar.net> 7bit

See also: www.piclist.com/techref/index.htm?key=crystal+tutorial
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Subject (change) Crystal Tutorial

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