High open-loop gain amplifier

Kind of an open loop question Liu, 

While some cadence sims might show that, typical ATE flows are limited to resolving more like a max 135dB. So there will not be any that actually specify that even if they have it. 

You can of course always take the highest Aol device that is otherwise suitable and add an inside the loop gain stage as a composite to raise that Aol (DC I am guessing in your question) - you would then need to deal with stability issues for the approach taken and the rest of the apps requirements. 

Hi Tom Liu,

can you tell more about your application?

In many (but not all) cases mounting two OPAmps in series can solve the problem.

Kai