I have designed a Butterworth highpass filter (HPF) of 4th order with cutoff frequency high enough to give a gain of $3$ at high frequencies. I want to find the inverse $z$-transform using MATLAB.
L=4;
OSR = 16;
[b,a] = butter(L,0.259,'high');
b = b/b(1);
fvtool(b,a);
H = tf(b,a,[],'variable','z^-1');
iztrans
doesn't seem to support tf
or zpk
.