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Design >> Analog Design >> DNL of '-1' and an INL of '0'
https://designers-guide.org/forum/YaBB.pl?num=1399912622

Message started by eternity on May 12^th, 2014, 9:37am

Title: DNL of '-1' and an INL of '0'
Post by eternity on May 12^th, 2014, 9:37am

Hi all,
I just have a small query regarding DNL and INL. I have a SAR ADC completely designed in verilogA. The DAC array in SAR ADC is implemented with ideal capacitors. When I tried calculating my DNL and INL through matlab scripts, it gives a DNL of '-1' and an INL of '0'.

But when I try calculating DNL in spectre, it gives a non-zero DNL plot. I am not sure where I am going wrong. Can anyone here help me in this.

Eternity

Title: Re: DNL of '-1' and an INL of '0'
Post by carlgrace on May 13^th, 2014, 3:44pm

It's very hard to respond without more information.

Are you saying the DNL for every code is -1 and the INL for every code is 0?

Your script is either not correctly calculating DNL and INL or you are not correctly getting the data into the script.

If you're using a ramp, the DNL of each is just the difference of each code from the average value across all codes and the INL is a running sum of the DNL.

Title: Re: DNL of '-1' and an INL of '0'
Post by eternity on May 15^th, 2014, 7:45am

Thanks for the reply and apologies in having been too abstract in my query.
yes, the dnl of all codes is -1 and inl of all codes is 0.
I attach a zoomed in screenshot of my transfer curve plot here that I use to compute DNL.
I sample 50 times for each code from zero to full scale level for this computation.

Thanks

Eternity