Note: This page has been translated by MathWorks. Click here to see

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

Chebyshev Type II filter design

`[b,a] = cheby2(n,Rs,Ws)`

`[b,a] = cheby2(n,Rs,Ws,ftype)`

`[z,p,k] = cheby2(___)`

`[A,B,C,D] = cheby2(___)`

`[___] = cheby2(___,'s')`

`[`

designs
a lowpass, highpass, bandpass, or bandstop Chebyshev Type II
filter, depending on the value of `b,a`

] = cheby2(`n`

,`Rs`

,`Ws`

,`ftype`

)`ftype`

and the
number of elements of `Ws`

. The resulting bandpass
and bandstop designs are of order 2`n`

.

**Note:** See Limitations for information about numerical issues that affect
forming the transfer function.

`[`

designs
a lowpass, highpass, bandpass, or bandstop digital Chebyshev Type II filter and returns its zeros, poles, and gain. This
syntax can include any of the input arguments in previous syntaxes.`z,p,k`

] = cheby2(___)

Chebyshev Type II filters are monotonic in the passband and equiripple in the stopband. Type II filters do not roll off as fast as Type I filters, but are free of passband ripple.

`cheby2`

uses a five-step algorithm:

It finds the lowpass analog prototype poles, zeros, and gain using the function

`cheb2ap`

.It converts poles, zeros, and gain into state-space form.

If required, it uses a state-space transformation to convert the lowpass filter into a bandpass, highpass, or bandstop filter with the desired frequency constraints.

For digital filter design, it uses

`bilinear`

to convert the analog filter into a digital filter through a bilinear transformation with frequency prewarping. Careful frequency adjustment the analog filters and the digital filters to have the same frequency response magnitude at`Ws`

or`w1`

and`w2`

.It converts the state-space filter back to transfer function or zero-pole-gain form, as required.

Was this topic helpful?