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A Kumar R

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how to do dynamic comparator offset simulation?
Dec 02^nd, 2014, 5:19am

Hi,

Because we can't perform a DC simulation on latch-based comparators, what is the way to measure offset?

Rite now, i am sweeping one of the input as slowly as possible. This is so to have slight changes from one clock edge to the next so that we can predict offset accurately. And then see where it trips.

is this correct?

Thanks,
Anil Reddy

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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: how to do dynamic comparator offset simulation? Reply #1 - Dec 2^nd, 2014, 6:33am Hi, works fine in case if you don't have any hysteresis and offset accuracy depends on your ramp rate. For accurate method go here.. http://www.designers-guide.org/Analysis/comparator.pdf Raj.
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hiSkill_11

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Re: how to do dynamic comparator offset simulation?
Reply #2 - Sep 8^th, 2015, 11:41pm

raja.cedt wrote on Dec 2^nd, 2014, 6:33am:

Hi,
works �fine in case if you don't have any hysteresis and offset accuracy depends on your ramp rate.
For accurate method go here..
http://www.designers-guide.org/Analysis/comparator.pdf

Raj.

Another question following this since they are related.
How can we evaluate noise for comparators used in high accuracy SAR ADC such 12b? How to setup and what's the integration bandwidth?
Thanks.

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sheldon

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Re: how to do dynamic comparator offset simulation?
Reply #3 - Oct 29^th, 2016, 5:58am

hiSkill,

� � There is a paper you can look at,

Method from �A Low-Noise Self-Calibrating Dynamic Comparator for
High-Speed ADCs�, Masaya Miyahara, Yusuke Asada, Daehwa Paik and
Akira Matsuzawa, A-SSCC 2008. IEEE Asian Solid-State Circuits
Conference, 2008, pg. 269-272 (used Spectre transient noise)

It discusses the transient noise based method for calculating dynamic
comparator noise. If you want information on using PSS/PNOISE for
dynamic comparator noise, contact your Cadence AE.

NOTE:
1) Using PNOISE does mean that the noise summary is available
2) The PSS based approach can be extended to calculation of the
� � sampling aperture.

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Sheldon

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