IIR.rar_iir 巴特沃斯_巴特沃斯滤波器

用 matlab 设计的 IIR 滤波器源程序

（1）IIR 一阶低通滤波器 P576

clear;

fi=1;fs=10;Gc2=0.9;

wc=2*pi*fi/fs;

omegac=tan(wc/2);

alpha=(sqrt(Gc2)/sqrt(1-Gc2))*omegac;

a=(1-alpha)/(1+alpha);

b=(1-a)/2;

clear;

fi=1;fs=10;Gc2=0.5;

wc=2*pi*fi/fs;

omegac=tan(wc/2);

alpha=(sqrt(1-Gc2)/(sqrt(Gc2)))*omegac;

a=(1-alpha)/(1+alpha);

b=(1+a)/2;

w=0:pi/300:pi;

Hw2=(tan(w/2).^2)./(alpha^2+(tan(w/2)).^2);

clear;

Gb2=0.5;

w0=0.35*pi;

deltaw=0.1*pi;

b=1/(1+tan(deltaw/2)*(sqrt(1-Gb2)/sqrt(Gb2)));

clear;

Gb2=10^(-Ac/10);

w0=0.35*pi;

deltaw=0.1*pi;

b=1/(1+tan(deltaw/2)*(sqrt(Gb2)/sqrt(1-Gb2)));

w=0:pi/500:pi;

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clear;

fs=20;fpass=4;fstop=5;

omega0=omegap/ep^(1/N);

K=floor(N/2);

for i=1:K

theta(i)=pi*(N-1+2*i)/(2*N);

end

for i=1:K

G(i)=omega0^2/(1-2*omega0*cos(theta(i))+omega0^2);

end

for i=1:K

a1(i)=2*(omega0^2-1)/(1-2*omega0*cos(theta(i))+omega0^2);

for i=1:K

a2(i)=(1+2*omega0*cos(theta(i))+omega0^2)/(1-2*omega0*cos(theta(i))+omega0^2);

end

if K<(N/2)

G0=omega0/(omega0+1);a0=(omega0-1)/(omega0+1);

end

w=0:pi/300:pi;

clear;

fs=20;fpass=5;fstop=4;

ep=sqrt(10^(Ap/10)-1);

es=sqrt(10^(As/10)-1);

N=ceil(log(es/ep)/log(omegas/omegap));

omega0=omegap/ep^(1/N);