陷波滤波器工作原理和结构

陷波滤波器是一种特殊的带阻滤波器,其阻带在理想情况下只有一个频率点,因此也被称为点阻滤波器。这种滤波器主要用于消除某个特定频率的干扰,例如,在各种测量仪器和数据采集系统中用于消除电源干扰的工频陷波器。以下为matlab的实现代码：% Matlab code for plotting the frequency response of digital notch filter% Implemented as all pass filter sectionclear; close allfs = 1e6;fn = 200e3;fb = 50e3;omega0T = fn/(fs/2)*pi;deltaT  = fb/(fs/2)*pi;a2 = (1-tan(deltaT/2))。/(1+tan(deltaT/2));a1 = (1+a2)。*cos(omega0T);B = [1 -a1 a2];A = [a2 -a1 1];[H1 W1] = freqz(B,A,1024,'whole');[H2 W2] = freqz(1,1,1024,'whole');H3 = (H1+H2)/2;h = figure(1);subplot(2,1,1);plot([-512:511]/1024*fs/1e6,20*log10(fftshift(abs(H3))),'b-','LineWidth',4);grid on; ylabel('amplitude,dB'); title('notch filter,fs=1MHz,fn=200kHz,fb=50kHz');axis([-0。5 0。5 -50 10]);subplot(2,1,2);plot([-512:511]/1024*fs/1e6,(fftshift(angle(H3)*180/pi)),'m-','LineWidth',4);grid on; xlabel('freq,MHz'); ylabel('angle,deg'); title('phase response');axis([-0。5 0。5 -180 180]);