% ladder example

fp = 10e6;
fs = 20e6;
rp =  2;
rs = 25;

[N, Wn] = buttord(2*pi*fp, 2*pi*fs, rp, rs, 's');
N

[b, a] = butter(N, Wn, 's');
H = tf(b, a);

bodemaghz(H);
fixfig;