User`s guide

Filter Realization Wizard
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6 Double-click the new Butter LPF block to see the Direct-Form II filter
realization that the Wizard created.
Example 2: Second Order Sections
Design an eighth-order, quarter-band, lowpass Butterworth filter using
second-order sections (SOS):
1 At the MATLAB command line, compute the second-order sections by
entering
[a,b,c,d] = butter(4,.25);
sos = ss2sos(a,b,c,d);
2 Configure the Wizard to use sos as the numerator of a Direct-Form II
structure:
- Select
Direct-Form II from the Type menu.
- Type
sos in the Numerator text field.
- Leave the
Denominator text field blank.