Re: [Discuss-gnuradio] CIC stop band

[Firas abbas]

Dear Hans,

I think you meant the frequency response of CIC+ HBF  filters. However, the USRP CIC decimation filter has 4 stages. I did MATLAB analysis for 4 stages CIC filter with decimation rate of 250 (as you requested) without the HBF. The spectrum analysis result is attached. The first plot is for entire range [0 to Fs/2]. The second one is zoomed near the interested band. You will see a huge theoretical gain (more than 190 dB) because of CIC bit growth.

Firas

Eric Blossom <address@hidden> wrote:
>  On Wed, May 16, 2007 at 04:00:24PM -0700, Hans Glitsch wrote:
> > Hello,
> > 
> > What is the stop band of the FPGA CIC filter?  How do I figure out the 
> > attenuation at a given frequency outside my bandwidth?
> > 
> > I'm decimating by 250.
> > 
> > Thanks,
> > Hans
>
> It's a
>  fourth order CIC.
> See http://users.snip.net/~donadio/cic.pdf for the transfer function.
>
> Eric
>
>
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