The Chebyshev Type II Filter, also known as the Inverse Chebyshev Filter, exhibits a Butterworth style, or maximally flat, passband, a moderate group delay, and an equiripple stopband.
Like the Butterworth filter, the passband attenuation of the Chebyshev Type II is defined to be -3.01 dB. However, FilterSolutions allows the user the option of selecting any passband attenuation, (in dB), that will define the filters cut-off frequency.
Below are examples of 5th order Chebyshev Type II low-pass, high-pass, bandpass and bandstop filters and the low pass step response. The stop band ratio is 1.2 in all the examples. It is useful to compare the stop band attenuation and the group delay to that of the Hourglass and Elliptic Filters.