CIC decimation function: integrator, downsample, comb filter

[Usman Hai]

cic decimation

I m working on DDC.

plz briefly describe the function of
Integrator
downsample
comb filter.

for CIC decimation. I know each block but I dont have idea y integrator and comb is used with each other.

Thanks
USMAN HAI

 

[yeewang]

cic comb canada

in short, integrator and comb are used in pairs to keep the spectrum intact thru decimation.

 

[brmadhukar]

Re: CIC decimation

Hi,
I feel it is quite difficult to explain in a forum like this. However refer the book
Uwe Meyer Baese -- Digital Signal Processing With FPGAs Chapter 5.
It is an excellant book and I think I had written about this before.

BRMadhukar

 

[blueteeth]

Re: CIC decimation

If you check the impulse response function,you can find cic is really a fir,so if comb's number is different to Integrator,the function will not be like that.
You can refer this article:
https://www.dspguru.com/info/tutor/cic.htm
or find the ieee paper to get more information:
Hogenauer, EB, "An Economical Class of Digital Filters for Decimation and Interpolation," IEEE Transactions
on Acoustics, Speech and Signal Processing, ASSP-29(2): pp. 155-162, 1981

 

[zcg]

Re: CIC decimation

you wrong . cic comb filter is IIR(one tap) not FIR


Can someone tell me the relationship of CIC decimation and GAIN?

Which part efect the final GAIN? (integrator or decimation or IIR?)

 

[altivec]

Re: CIC decimation

I suggest you read the paper from Matthew Donadio ( link given by blueteeth )

Can someone tell me the relationship of CIC decimation and GAIN?

Gain is to be said as G = (RxM)^N where :
- R is the rate change
- M the delay introduced in the IIR filters
- N the numbers of integrators and decimators

Which part efect the final GAIN? (integrator or decimation or IIR?)

well, the gain from CIC is strongely dependant from all the parameters (R,M,N), that makes hard to predict its behavior
there's also issue with bandwidht to deal with

regards

 

[Ansunamu]

Re: CIC decimation

CIC is not IIR . It is FIR

You can find lots of paper dicuss about CIC on the IEEE Xplore !

I am implementing the CIC for decimation and interpolation either .

 

[altivec]

Re: CIC decimation

CIC is not IIR . It is FIR

no CIC works with IIR and FIR filters
the integrators blocks are IIR filters, otherwise they would'nt integrate anything.
the comb blocks are FIR filters

regards

 

[bamboo]

Re: CIC decimation

Maybe this article may give you some idea about CIC

 

[sigma]

Re: CIC decimation

Hi
Try xilinx coregen documentation on CIC filters.

Thanks

 

[sanwolf]

CIC decimation

integrator is very easy implement.you can let ouput value is saved in a delay-register,than add it to input now