IIR filter

IIR FILTER DESIGN

clc;

close all;

clear all;

rp=input('enter the pass band ripple');

rs=input('enter the stop band ripple');

wp=input('enter the pass band freq');

ws=input('enter the stop band freq');

fs=input('enter the sampling feq');

w1=2*wp/fs;

w2=2*ws/fs;

[h,wn]=buttord(w1,w2,rp,rs);

[b,a]=butter(h,wn);

w=0:.01:pi;

[h,om]=freqz(b,a,w);

m=20*log10(abs(h));

an=angle(h);

subplot(2,1,1);

plot(om/pi,m);

ylabel('gain in db....>');

xlabel('(a) normalised frequency>');

subplot(2,1,2);

plot(om/pi,an);

xlabel('(b) normalised frequency');

ylabel('phase in radian');