hello all,

        when i simulated the dc opt of an diff amp(basic diff amp with diode connected load) i have seen a slightly different operating point(e.g if set 0.9v at the output it shows 970m) and the tail current is not at what i wanted to be,although individual components are designed perfectly.but when i combined transistors to form diff amp i have been facing the above mentioned prob.

can any one suggest a solution to solve the prob?

hi,
    Plz check if all your transistorss including your tail current source is in saturtation/sub-Vt region of Operation(MOS) as you intended them to be. Also check if the vds drop across 1/gm resistance of diode connected load is leaving enough vds across input MOS for it to be in saturation. And yeah, post your schematic with op points.

regards,
Mayank.