Does Monte carlo variation depends on input common mode of amplifier?

Status
Not open for further replies.
P

pmr9

Junior Member level 2
Joined
Jul 16, 2007
Messages
20
Helped
3
Reputation
6
Reaction score
1
Trophy points
1,283
Visit site
Activity points
1,377
Hi All,
I have a question regarding MC variation (offset of amplifier), Does Monte carlo variation depends on input common mode of amplifier??

Thanks
 

Input common-mode (voltage) does not typically have much affect on input offset voltage of a well designed differential amplifier.
 

Thanks crutschow, Just thinking that reduced common mode will reduce gm, that increases the mismatch contribution from the load devices. Considering the relation: (gm_diff/gm_load)*Vth_mismatch_loads
 

When common mode position drives the front end into a
linear region (MOS) or saturation or near-cutoff (BJT)
the gain will be reduced. The common mode position at
which this rolls on, is process / temp / voltage variable.
So at extreme common mode positions you may see
"enhanced" process sensitivity (like, if you're 0.5V from
the lower rail with a NMOS front end, and VTN varies
0.3 - 0.7V, half of the distribution might be into cutoff
of the diff pair tail current and gain tanks, bandwidth
pulls in, etc.).

This is why rail-rail input stages are interesting.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…