Re: differential mode output from opamp with current mirror
The main point is - If you check two output resistance of differential pair with current mirror, one is 1/gm, another is rds||rds - which will lose symmetrical feature. The better way is to use both diode connected MOS as load, or both biased current load. Now transconductance of each side is 0.5gm.
For diff-in diff-out opamp, you have to consider the circuit stablization issue of common-mode output voltage.