Butterworth n-th order lowpass filter implementation using cascaded second-order sections (SOS).
Computed SOS are identical to the general MATLAB design result:
[z, p, k] = butter(order, cutoffFreq*2*pi, 'low', 's'); [zd, pd, kd] = bilinear(z, p, k, samplingFreq); [sos, g] = zp2sos(zd, pd, kd);
Step response and SOS matrix of an 11-th order Butterworth lowpass filter