Filter Design Toolbox™

butter - Butterworth IIR filter design using specification object

Syntax

hd = design(d,'butter')
hd = design(d,'butter',designoption,value...)

Description

hd = design(d,'butter') designs a Butterworth IIR digital filter using the specifications supplied in the object d.

hd = design(d,'butter',designoption,value...) returns a Butterworth IIR filter where you specify a design option and value.

To determine the available design options, use designopts with the specification object and the design method as input arguments as shown.

designopts(d,'method')

For complete help about using butter, refer to the command line help system. For example, to get specific information about using butter with d, the specification object, enter the following at the MATLAB prompt.

help(d,'butter')

Examples

The first example constructs a default lowpass filter specification object and uses it to design a Butterworth filter.

d = fdesign.lowpass;
designopts(d,'butter')

ans = 

    FilterStructure: 'df2sos'
       MatchExactly: 'stopband'
hd = design(d,'butter','matchexactly','stopband');

Example 2 constructs a highpass filter specification object with order (n) and cutoff frequency (fc) specifications, and then designs a Butterworth filter from the object.

d = fdesign.highpass('n,fc',8,.6);
design(d,'butter');

See Also

cheby1, cheby2, ellip

block

ca2tf