what is better solution to feed current mirror through 1uA current path or through voltage one ?
the second question is about opamp's biasing. do you bias it locally by simple mirror and diode or do you supply current mirror with reference curent ?
Related to opam biasing .....first step is control the offset null voltage by having a potention meter and resistor configuation with -VCC .....and in order to have low baising current I generally use one more stage of buffer opamp configuaration at the start.....