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.
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
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
zcg said:
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
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