%積分梳狀濾波器的設計
clear;
clc;
%積分濾波器的響應

b1=1;
a1=[1 -1];
% freqz(b1,a1,'whole');

hold on;
%梳狀濾波器的響應
D=9;
b2=[1 zeros(1,D-1) -1];
a2=1;
% freqz(b2,a2,'whole');

%積分梳狀濾波器響應
b3=b2;
a3=a1;
% freqz(b3/D,a3,'whole')

%兩只內插因子為9的CIC級聯響應
b4=conv(b3,b3);
a4=conv(a3,a3);
% freqz(b4/D^2,a4,'whole')

%三只內插因子為9的CIC級聯響應
b5=conv(b4,b3);
a5=conv(a4,a3);
% freqz(b5/D^3,a5,'whole');

%四只內插因子為9的CIC級聯響應
b6=conv(b4,b4);
a6=conv(a4,a4);
freqz(b6/D^4,a6,'whole');

%五只內插因子為9的CIC級聯響應
b7=conv(b6,b3);
a7=conv(a6,a3);
freqz(b7/D^5,a7,'whole');