raja.cedt wrote on Sep 17th, 2009, 10:05pm:hi rg,
i didn't understand last para in your post (average mismatch....etc)...if you decrease the device size all secondary effects will decrease vth and leakage will increase. And i feel differential configuration would be help full to cancel this one.
Guess I'm confusing everyone...
I was talking talking about charge injection in differential circuits. As you know, if it is matched the injected charge is common mode and not an issue.
On the other hand, if there is a mismatch in the injected charge you will get an error signal. It follows that you would like to match the charge injections as well as possible. Most people assume that larger switches will match better, but this is not true for matching charge injection. The matching improves as sqrt(area), but the amount of charge increase proportional to area.