Programs of IIR Filters

Dear All Students,

  Here I am providing the required Matlab Program to execute IIR - Filters i.e. Butterworth, Chebshev Type-I, Chebshev Type-II. Unlike Previously stated, write these programs in some book/paper. Don't write these programs directly in observations. After executing the programs you have to write in observations.

So, the following are the Programs:

1) Butterworth IIR Low-Pass Filter

2) Butterworth IIR High-Pass Filter

3) Chebshev Type-I IIR Low-Pass Filter

4) Chebshev Type-II IIR High-Pass Filter

5) Chebshev Type-II IIR Low-Pass Filter

6) Chebshev Type-II IIR High-Pass Filter

The respective code's are as follows:

IIR Filters

Program 1:

%Program to find frequency respnse of butterworth IIR analog Low-pass Filter

wp=input('enter passband cuttoff frequency:');

ws=input('enter stopband cuttoff frequency:');

rp=input('enter passband ripple in db:');

rs=input('enter stop band ripple in db:');

fs=input('enter the sampling frequency:');

w1=2*wp/fs;

w2=2*ws/fs;

[n,wn]=buttord(w1,w2,rp,rs,'s');

[b,a]=butter(n,wn,'s');

w=0:0.01:pi;

[h,omega]=freqs(b,a,w);

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

an=angle(h);

subplot(2,1,1);

title('magnitude response of LPF');

plot(omega/pi,gain);

xlabel('normalized frequency');

ylabel('phase in radians');

subplot(2,1,2);

title('phase in radians');

plot(omega/pi,an);

xlabel('normalized frequency');

ylabel('phase in radians');

Program 2:

%Program to find frequency respnse of butterworth IIR analog High-pass Filter

wp=input('enter passband cuttoff frequency:');

ws=input('enter stopband cuttoff frequency:');

rp=input('enter passband ripple in db:');

rs=input('enter stop band ripple in db:');

fs=input('enter the sampling frequency:');

w1=2*wp/fs;

w2=2*ws/fs;

[n,wn]=buttord(w1,w2,rp,rs,'s');

[b,a]=butter(n,wn,'high','s');

w=0:0.01:pi;

[h,omega]=freqs(b,a,w);

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

an=angle(h);

subplot(2,1,1);

title('magnitude response of LPF');

plot(omega/pi,gain);

xlabel('normalized frequency');

ylabel('phase in radians');

subplot(2,1,2);

title('phase in radians');

plot(omega/pi,an);

xlabel('normalized frequency');

ylabel('phase in radians');

Program 3:

%Program to find frequency respnse of Chebyshev Type-I IIR analog Low-pass Filter

wp=input('enter passband cuttoff frequency:');

ws=input('enter stopband cuttoff frequency:');

rp=input('enter passband ripple in db:');

rs=input('enter stop band ripple in db:');

fs=input('enter the sampling frequency:');

w1=2*wp/fs;

w2=2*ws/fs;

[n,wn]=cheb1ord(w1,w2,rp,rs,'s');

[b,a]=cheby1(n,wn,'s');

w=0:0.01:pi;

[h,omega]=freqs(b,a,w);

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

an=angle(h);

subplot(2,1,1);

title('magnitude response of LPF');

plot(omega/pi,gain);

xlabel('normalized frequency');

ylabel('phase in radians');

subplot(2,1,2);

title('phase in radians');

plot(omega/pi,an);

xlabel('normalized frequency');

ylabel('phase in radians');

Program 4:

%Program to find frequency respnse of Chebyshev Type-I IIR analog High-pass Filter

wp=input('enter passband cuttoff frequency:');

ws=input('enter stopband cuttoff frequency:');

rp=input('enter passband ripple in db:');

rs=input('enter stop band ripple in db:');

fs=input('enter the sampling frequency:');

w1=2*wp/fs;

w2=2*ws/fs;

[n,wn]=cheb1ord(w1,w2,rp,rs,'s');

[b,a]=cheby1(n,wn,'high','s');

w=0:0.01:pi;

[h,omega]=freqs(b,a,w);

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

an=angle(h);

subplot(2,1,1);

title('magnitude response of LPF');

plot(omega/pi,gain);

xlabel('normalized frequency');

ylabel('phase in radians');

subplot(2,1,2);

title('phase in radians');

plot(omega/pi,an);

xlabel('normalized frequency');

ylabel('phase in radians');

Program 5:

%Program to find frequency respnse of Chebyshev Type-II IIR analog Low-pass Filter

wp=input('enter passband cuttoff frequency:');

ws=input('enter stopband cuttoff frequency:');

rp=input('enter passband ripple in db:');

rs=input('enter stop band ripple in db:');

fs=input('enter the sampling frequency:');

w1=2*wp/fs;

w2=2*ws/fs;

[n,wn]=cheb2ord(w1,w2,rp,rs,'s');

[b,a]=cheby2(n,wn,'s');

w=0:0.01:pi;

[h,omega]=freqs(b,a,w);

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

an=angle(h);

subplot(2,1,1);

title('magnitude response of LPF');

plot(omega/pi,gain);

xlabel('normalized frequency');

ylabel('phase in radians');

subplot(2,1,2);

title('phase in radians');

plot(omega/pi,an);

xlabel('normalized frequency');

ylabel('phase in radians');

Program 6:

%Program to find frequency respnse of Chebyshev Type-II IIR analog High-pass Filter

wp=input('enter passband cuttoff frequency:');

ws=input('enter stopband cuttoff frequency:');

rp=input('enter passband ripple in db:');

rs=input('enter stop band ripple in db:');

fs=input('enter the sampling frequency:');

w1=2*wp/fs;

w2=2*ws/fs;

[n,wn]=cheb2ord(w1,w2,rp,rs,'s');

[b,a]=cheby2(n,wn,'high','s');

w=0:0.01:pi;

[h,omega]=freqs(b,a,w);

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

an=angle(h);

subplot(2,1,1);

title('magnitude response of LPF');

plot(omega/pi,gain);

xlabel('normalized frequency');

ylabel('phase in radians');

subplot(2,1,2);

title('phase in radians');

plot(omega/pi,an);

xlabel('normalized frequency');

ylabel('phase in radians');

Do execute these programs and then write in observations. And get it corrected as early as possible.

with regards,

B V K