carlgrace wrote on Apr 18th, 2012, 5:30pm:You don't give enough information. For example, what is your reference voltage? That will tell us a lot. The clock isn't very fast, so really these specs probably aren't that bad.
You have two choices, you can make your reference really really slow (and low impedance) or you can make it so fast it settles in 1/2 clock period. The easiest thing to do, if you can spare the pads, is to bypass the heck out of the reference so it's peak transient is less than 1/2 LSB.
If he makes it "slow" he'll have to watch out for signal dependent loading, which, if low frequency, will change the I*Rout drop of the buffer. Depending on the design, the drop could be more than 1/2 LSB.
I'm not sure open loop gain is all that important as it will only scale the reference slightly, which will result in a gain error. Often times people don't care about gain error. If they do, then your open-loop gain must be enough so that A/(1+A*β) < 1/2 LSB