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Measurements >> Other Measurements >> Measure the DNL/INL by slow frequency sin wave
https://designers-guide.org/forum/YaBB.pl?num=1225701396

Message started by Monkeybad on Nov 3^rd, 2008, 12:36am

Title: Measure the DNL/INL by slow frequency sin wave
Post by Monkeybad on Nov 3^rd, 2008, 12:36am

Hello! everyone,
I find some data about measuring the DNL/INL of an ADC by using slow frequency sin wave. Actually this data is from "EE315: VLSI Data Conversion Circuits" in STANFORD UNIVERSITY, Department of Electrical Engineering. Here is the MATLAB code.

function [dnl,inl] = dnl_inl_sin(y);
%DNL_INL_SIN
% dnl and inl ADC output
% input y contains the ADC output
% vector obtained from quantizing a
% sinusoid
% Boris Murmann, Aug 2002
% Bernhard Boser, Sept 2002
% histogram boundaries
minbin=min(y);
maxbin=max(y);
% histogram
h = hist(y, minbin:maxbin);
% cumulative histogram
ch = cumsum(h);
% transition levels
T = -cos(pi*ch/sum(h));
% linearized histogram
hlin = T(2:end) - T(1:end-1);
% truncate at least first and last
% bin, more if input did not clip ADC
trunc=2;
hlin_trunc = hlin(1+trunc:end-trunc);
% calculate lsb size and dnl
lsb= sum(hlin_trunc) / (length(hlin_trunc));
dnl= [0 hlin_trunc/lsb-1];
misscodes = length(find(dnl<-0.9));
% calculate inl
inl= cumsum(dnl);

Anyone can explain how this method work? Especially what the red line means. Thanks!

Title: Re: Measure the DNL/INL by slow frequency sin wave
Post by jbdavid on Nov 3^rd, 2008, 2:41pm

Joey Doernberg explained it here:
("Full-speed testing of A/D converters" - Doernberg, JSSC - DEC 1984)
you can find it at

http://ieeexplore.ieee.org/search/srchabstract.jsp?arnumber=1052232&isnumber=22599&punumber=4&k2dockey=1052232@ieeejrns&query=%28%28full-speed+testing+of+a%2Fd+converters%29%3Cin%3Emetadata%29&pos=0&access=no

Title: Re: Measure the DNL/INL by slow frequency sin wave
Post by ywguo on Nov 4^th, 2008, 12:02am

Hi,

It is not necessary to apply a SLOW sine wave. A fast sine wave is also feasible only if it is pure enough.

Yawei

Title: Re: Measure the DNL/INL by slow frequency sin wave
Post by Frank Wiedmann on Nov 4^th, 2008, 1:24am

A quick Google search also finds http://www.maxim-ic.com/appnotes.cfm/appnote_number/2085/.