On Sep 4, 2008, at 12:37 PM, Matt Ettus wrote:
Re CIC gain, there's a also a decimation specific shifter involved in
the path. Please take a look at
Yes. You guys have the R^4 formula right, but the shifter takes
back most of the gain. The actual gain from the CIC decimator once
you include the shifter is:
R^4 / ( 2^ ceiling(log2(r^4)))
I hope that is readable. Basically, if R is a power of 2, then the
gain is exactly 1. If R is not a power of 2 then the gain is in the
range of (0.5,1).
Matt
Well, if the gain is really in (0.5, 1), that makes my missing gain
situation worse. I would be hunting for more than 20,000 in that case.
Also, it is inconsistent with my measurements that show that the gain
increases by a total of 26 dB as the decimation rate
is changed from 96 to 256.
---
Where is the shifter you are referring to? Is it in a non-recursive
implementation of the CIC filter?
Dick...
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