Matalb-models-for-sigma-delta-ADC

simulink models of ctsdm and dtsdm ADC

Simulink models

ctsdm

3rd order 1 bit quantizer fir dac

1. 3rd order loopfilter
2. 1 bit quanntizer
3. 4 tap fir dac/3 tap firc dac

dtsdm

Script

1. fft_ex.m

%FFT

Nfft = 2^20;
xfft = fs*(0:Nfft/2)/Nfft

win = blackman(n);
win = win';

v = out.v
v = v'
v1 = v.*win

Y = fft(v1,Nfft);
%Y = fft(X,n) 返回 n 点 DFT。如果未指定任何值，则 Y 的大小与 X 相同。
%如果 X 是向量且 X 的长度小于 n，则为 X 补上尾零以达到长度 n
P2 = abs(Y/Nfft);
P1 = P2(1:Nfft/2+1);
P1(2:end-1) = P1(2:end-1)*2;

V1 = Y(1:Nfft/2+1);

figure;
semilogx(xfft,20*log10(abs(V1/max(V1))));

% semilogx(xfft,P1);
hold on;

legend('before the digital filter');
grid on;

xlabel('Frequency [Hz]');
ylabel('Normalized magnitude [dB]');
title(['3th-order SDM with 1-bit quantizer']);

Markdown tutorial[菜鸟教程][1]

[1] https://www.runoob.com/markdown/md-link.html