IIR滤波器FPGA源码(4阶级联型)

FilterOrder = 4; data_width = 13; % Data input bit width max_data = 2^(data_width-1)-1; min_data = -max_data; biquad_number = floor((FilterOrder+1)/2); % Filter Coefficients %FeedForward = [0.2958 0.5876 0.2958]; %FeedBack = [1.0000 0.2138 0.4518]; [FeedForward,FeedBack] = ellip(FilterOrder,3,50,300/500); figure(1); freqz(FeedForward,FeedBack); title('Frequency Response (full precision coefficients)'); figure(2); zplane(FeedForward,FeedBack); title('Zero-pole plot using full precision coefficients'); [z,p,k] = tf2zp(FeedForward,FeedBack); SecOrd = zp2sos(z,p,k); %Impulse response Inp = zeros(300,1); Inp(10) = max_data; %Impulse Response Plotting figure(3); biquad_output=zeros(biquad_number,min(length(Inp),300)); biquad_output(1,:) = iir_biquad(SecOrd(1,:), Inp * 2^4); for i=1: biquad_number - 1; biquad_output(i+1,:) = iir_biquad(SecOrd(i+1,:), biquad_output(i,:)/2^10); end output = biquad_output(biquad_number,:) / 2^14; i_output = filter(FeedForward, FeedBack, Inp); impulse_output = output; sz = size(output); max_x = max(sz); xline = linspace (0, max_x - 1, max_x); plot (xline, output,'r'); title ('Time Display of Impulse Response'); grid on; zoom on; outfile1 = fopen('imp_in.txt','w'); fprintf(outfile1, '%d\n', Inp); fclose(outfile1); outfile1 = fopen('m_Inpulse_out.txt','w'); fprintf(outfile1, '%d\n', output); fclose(outfile1); % Frequency Domain Plotting to_plot = output; figure(4); freqdat = fft(to_plot); absdat = abs(freqdat); maxdat = max (absdat); logdat = 20*log10(absdat); sz = size(to_plot); numpts = max(sz); freq_res = 1/numpts; xline = linspace (0, ( (1/2)- freq_res ), round(numpts/2) ); plot (xline, logdat(1: round(numpts/2) ), 'b'); title ('Frequency Display of Impulse Response'); grid on; zoom on; xlabel ('Frequency'); ylabel ('Magnitude - dB'); %Step Response step= zeros(300,1); for i=10:300 step(i) = max_data; end; %step Response Plotting figure(5); biquad_output=zeros(biquad_number,min(length(step),300)); biquad_output(1,:) = iir_biquad(SecOrd(1,:), step * 2^4); for i=1: biquad_number - 1; biquad_output(i+1,:) = iir_biquad(SecOrd(i+1,:), biquad_output(i,:)/2^10); end output = biquad_output(biquad_number,:) / 2^14; s_output = filter(FeedForward, FeedBack, step); step_output = output; sz = size(output); max_x = max(sz); xline = linspace (0, max_x - 1, max_x); plot (xline, output,'r'); title ('Time Display of Step Response'); grid on; zoom on; outfile2 = fopen('step_in.txt','w'); fprintf(outfile2, '%d\n', step); fclose(outfile2); outfile2 = fopen('m_Step_out.txt','w'); fprintf(outfile2, '%d\n', output); fclose(outfile2); % Frequency Domain Plotting to_plot = output; figure(6); freqdat = fft(to_plot); absdat = abs(freqdat); maxdat = max (absdat); logdat = 20*log10(absdat); sz = size(to_plot); numpts = max(sz); freq_res = 1/numpts; xline = linspace (0, ( (1/2)- freq_res ), round(numpts/2) ); plot (xline, logdat(1: round(numpts/2) ), 'b'); title ('Frequency Display of Step Response'); grid on; zoom on; xlabel ('Frequency'); ylabel ('Magnitude - dB'); %Ramdom Input random = round((rand(1, 100)-0.5)*(2^data_width-2)-1); int_random = round(random); zero_init = zeros(10,1); zero_init = zero_init'; int_random = [zero_init int_random]; % Saturating Input Value a_in = find (int_random > max_data); b_in = find (int_random < min_data); if (~isempty(a_in)|~isempty(b_in)) lenax = length (a_in); lenbx = length (b_in); for i = 1:lenax int_random(a_in(i)) = max_data; end for i = 1:lenbx int_random(b_in(i)) = min_data; end end %Random Response Plotting % This is the stimulus used in random.vwf int_random = [0 0 0 0 0 0 0 0 0 0 -3508 -1735 48 3635 -3176 1837 -930 -545 240 2686 3670 -3578 -3903 3414 -3543 0 0 0 0 0 0]; figure(7); biquad_output=zeros(biquad_number,min(length(int_random),300)); biquad_output(1,:) = iir_biquad(SecOrd(1,:), int_random * 2^4); for i=1: biquad_number - 1; biquad_output(i+1,:) = iir_biquad(SecOrd(i+1,:), biquad_output(i,:)/2^10); end output = biquad_output(biquad_number,:) / 2^14; r_output = filter(FeedForward, FeedBack, int_random); random_output = output; sz = size(output); max_x = max(sz); xline = linspace (0, max_x - 1, max_x); plot (xline, output,'r'); title ('Time Display of random Response'); grid on; zoom on; outfile3 = fopen('rand_in.txt','w'); fprintf(outfile3, '%d\n', int_random); fclose(outfile3); outfile3 = fopen('m_Random_out.txt','w'); fprintf(outfile3, '%d\n', output); fclose(outfile3); % Frequency Domain Plotting to_plot = output; figure(8); freqdat = fft(to_plot); absdat = abs(freqdat); maxdat = max(absdat); logdat = 20*log10(absdat); sz = size(to_plot); numpts = max(sz); freq_res = 1/numpts; xline = linspace (0, ( (1/2)- freq_res ), round(numpts/2) ); plot (xline, logdat(1: round(numpts/2) ), 'b'); title ('Frequency Display of Random Response'); grid on; zoom on; xlabel ('Frequency'); ylabel ('Magnitude - dB');