I have no problem In cascading filters, but I do not think I can cascade 2 x 8 poles filters. I don't think it worksAlthough you did not give a clue of the selectivity, it is unlikely to be able to implement an analog filter in such an order. Consider cascading lower-order filters.
I suppose, a high order active filter will be implemented by cascaded second order building blocks (Bi-quads) anyway.Consider cascading lower-order filters.
I need to have a stopband around 2kHz (to be defined exactly), and a falloff of ~90dB/octave.TI online filter design tool can calculate higher order filters. Chebyshev filter coefficients can be also calculated with matlab. For steepest transition band, you might prefer an elliptical (Cauer) filter.
Can you give a full pass- and stop band specification to better explain your requirements?
Unfortunately I need at least 90dB/octave, perhaps a bit more. 80 is not enough. How do I implement 9 or 10th order? I have never seen an implementation8th order 1dB Chebyshev gives already around -80 dB at 0.5 fc.
9th order -90 dB.
This statement is far away from truth.Unfortunately all the tables available do not go beyond 8 poles.
How do I implement 9 or 10th order? I have never seen an implementation
I don't think so.so if you combine two identical 2nd order butterworth filters, with the buffer stage between,
the result is a fourth order filter with an unchanged cutoff frequency
Danadakk:
I don't like to hi-jack threads, so I will keep this short.
Based on your multiple postings, your knowledge of PSoC seems to be very extensive.
Hopefully you will open someday a thread "PSoC for Dummies"
Sorry for replying after such a long time, but I have been traveling and I had some issue so that I could not connect.This statement is far away from truth.
Transfer function of N-order filter consists N-order polynomial. Chebyshev filter uses Chebyshev polynomials, Butterworth uses Butterworth polynomials and so on.
We know how to generate such polynomials. Hint - look for Chebyshev polynomials in the web.
As above, cascade of 1st order or 2nd order well known stages, which poles/zeros following polynomials zeros.
Well.. the answer is not simple.One significant issue is component tolerances.
Out of curiosity why not a digital filer ?
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