Iowa Hills Software Digital and Analog Filters
Chebyshev IIR Filters Home
The Chebyshev filter is well known and described in all the texts. Its transition band can be made narrower by adding ripple to the pass band. This also makes the group delay variation and subsequent distortion worse.
Here are is an example of Chebyshev IIR low pass response. Note the severe ringing in the step response.
A good way to judge the merits of the Chebyshev is to compare it to the Butterworth. Only 8 poles are needed for approximately the same stop band attenuation as a 14 pole Butterworth, but it has pass band ripple, and a peak math value of 78 as compared to 12 for the Butterworth.
The free Iowa Hills IIR Filter Designer will synthesize Chebyshev filters up to 20 poles.
The source code for generating Chebyshev low pass prototype filters is given on our Example C Code Page.
Chebyshev IIR Filters
Inverse Chebyshev IIR Filters
Elliptic IIR Filters