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Design >> Mixed-Signal Design >> How does the kickback noise really infect on the resolution in SARADC?
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Message started by Jacki_2016 on Jun 30^th, 2022, 2:00am

Title: How does the kickback noise really infect on the resolution in SARADC?
Post by Jacki_2016 on Jun 30^th, 2022, 2:00am

Hi,

we normally discuss the kickback noise of the comparator, but how it really infects on the resolution of the SARADC? From my opinion, take a dynamic comparator as an example, if we can see the kickback noise > 1LSB, then it will impact on the final bits since what I can see is the kickback noise will stay until next reset phase.
Any thoughts on it?
Thank you.

Title: Re: How does the kickback noise really infect on the resolution in SARADC?
Post by Horror Vacui on Jul 26^th, 2022, 5:05am

I am not sure whether I understand your question correctly. Kickback noise happens right after the decision is made in the comparator, hence it won't affect the current decision. The positive feedback will increase the dV/dt, which will couple to other nodes through the ever-present capacitances. It will disturb the input and the reference of the comparator. These signals should return to their real values before the next comparison is made in the comparator.

Title: Re: How does the kickback noise really infect on the resolution in SARADC?
Post by Jacki_2016 on Aug 2^nd, 2022, 6:07am

Thank you very much for your reply. Yes, you are right, the kickback noise will disturb other nodes (like reference voltage), or else due to the hysteresis, it will not impact on the current decision.