jimlux at earthlink.net
Tue Jun 21 14:49:41 UTC 2011
It just came to me..
You're not using CORDIC as a replacement for both the phase accumulator
and cos LUT, but JUST instead of the LUT, so you ARE doing the "give me
cos(theta)" on every sample.
So then, it's a trade between a big ROM LUT or a bunch o'gates for
CORDIC. And for big N the bunch o'gates is probably going to be easier:
16 bit phase and wanting 16 bits out would be a 64kbit ROM (assuming you
didn't do the usual thing of only needing 1/4 cycle)..
I suppose, too, if you're building a digital up/down converter or mixer,
rather than a LUT feeding a pair of multipliers for I/Q, the CORDIC
scheme lets you essentially do it on the fly.
More information about the time-nuts