definition of dnl and inl
U just need to measure SNR, THD, SNDR and DR, and not nessary to measure INL and DNL for sigma delta modulator. and the SNR only contain noise, no need for distortion. the distortion is measure by SNDR and THD. u can use the following matlab script to exact the signal from the digital bit stream.
then do the PSD of (in-outx), u can get the quantization noise PSD. integrate the inband noise u get the IBN. then u can calulate the SNR,SNDR, THD ...
function [outx,amp,ang] = sinusx(in,f,n)
%in=bitstream ; f = normoize freq; n=number of point
%outx= Extraction of a sinusoidal signal; amp=amplitude; ang=phase
%
sinx=sin(2*pi*f*[1:n])';
cosx=cos(2*pi*f*[1:n])';
in=in(1:n);
a1=2*sinx.*in;
a=sum(a1)/n;
b1=2*cosx.*in;
b=sum(b1)/n;
outx=a.*sinx+b.*cosx;
angTemp=atan(b/a);
ang=angTemp/(2*pi*f);
amp=a/cos(angTemp);