User`s guide

Filter Realization Wizard
5-185
Example 1: Direct Form II
Design an fourth-order, quarter-band, lowpass Butterworth filter:
1 At the MATLAB command line, compute the filter coefficients by entering
[b,a] = butter(4,.25);
2 Launch the Filter Realization Wizard by double-clicking on the icon in the
Filter Realizations library.
3 Configure the Wizard to use b and a as the numerator and denominator of a
Direct-Form II structure:
- Select
Direct-Form II from the Type menu.
- Type
b in the Numerator text field.
- Type
a in the Denominator text field.
4 Type a name for the new filter subsystem in the Block Name field. The
example uses
Butter LPF.
The GUI with these settings is shown below.
5 Press the Build button to create the specified filter subsystem in a new
model window.