Iowa Hills Software Digital and Analog Filters
Inverse Chebyshev IIR Filters Home
The Inverse Chebyshev filter allows for narrower transition bands by limiting the attenuation in the stop band as shown here.
This shows how the overshoot and ringing are affected by the stop band attenuation setting.
The Inverse Chebyshev shows it's merits when compared to a Butterworth. Depending on the number of bits in the ADC, it may not be possible to get more than 60 dB of attenuation, so in this case, the Inverse Chebyshev does the same task with 8 poles as a 14 pole Butterworth. Both filters have a peak math register value of slightly less than 13.
The free Iowa Hills IIR Filter Designer will synthesize Inverse Chebyshev filters up to 15 poles.
The source code for generating Inverse Chebyshev low pass prototype filters is given on our Example C Code Page.
Chebyshev IIR Filters
Inverse Chebyshev IIR Filters
Elliptic IIR Filters