>I am designing cic filter and compensation filter. Fs
is the signal sample rate and R is the down sample rate with cic filter.I search
most of articles about cic+compensation filter design. And most of Amplitude to
Frequence feature for cic+compensation filter is shown in the Fs frequency but
not Fs/R.
>In my understanding of cic+compensation filter, the Amplitude to Frequence
feature should be shown in Fs/R frequency. Because after cic filter, sample rate
has been down to Fs/R and compensation filter work at Fs/R frequency. So I think
Amplitude to Frequence feature for cic+compensation filter should be in Fs/R
frequency. Am I right?
>I really hope to listen to your idear and appreciate your reply.
>
Another way to look at it is from the normalized sample rate. This way we
don't need to be confused about the sample rate. You can take the results
from any paper/book and normalize.
It is valid to look at the response from either Fs or Fs/R perspective in
absolute terms. You should notice that even though it is from the original Fs
perspective there should be nothing of interest above the new Nyquist, Fs/(2*R).
But most will feel more comfortable from the Fs/R perspective which you should
easily be able to convert the axis units.
.chris