g_bilinear.m

butterworth+chebcv的matlab 程序

%实现Butterworth模拟滤波器的去归一化并且进行双线性变换子程序u_buttap.m
function[b,a]=g_bilinear(N,Omegac,fs)
z = [];
p =exp(j*((2*(1:2:N-1)-1+N)/(2*N))*pi)
p=[p;conj(p)];
p = p(:);
if rem(N,2)==1   % n is odd
    p = [p; -1];
end
k = real(prod(-p));
p=p*Omegac;k=k*Omegac^N;
%B=real(poly(z));
%b0=k;
%b=k*B;
fs=2*fs;
ad=(fs+p)./(fs-p);
zd=(fs+z)./(fs-z);
kd=(prod(fs-z)./prod(prod(fs-p)));

bd=[zd;-ones(length(p)-length(z),1)];
a=poly(ad);
b=poly(bd);
b=b*kd*k;