设计一个模拟带通滤波器,其Ap=1dB,As=34dB,通带从200HZ到300HZ,阻带在100HZ-400HZ,设计满足上述条件的巴特沃斯滤波器 切比雪夫1 切比雪夫2 椭圆滤波器 。
參考答案:wp1=0.45*pi; wp2=0.65*pi;
ws1=0.3*pi; ws2=0.75*pi;
Rp=1; Rs=40;
Wp=[wp1/pi,wp2/pi]; Ws=[ws1/pi,ws2/pi];
[N,Wn]=cheb1ord(Wp,Ws,Rp,Rs);
[B,A]=cheby1(N,Rp,Wn);
[h,omega]=freqz(B,A,64);
subplot(2,2,3);stem(omega/pi,abs(h));
xlabel('\omega/\pi');ylabel('|H(z)|');
subplot(2,2,4);stem(omega/pi,20*log10(abs(h)));
xlabel('\omega/\pi');ylabel('增益.dB');