Patent ID: 7535302

Claim:
An operational amplifier comprising: a first differential pair having a first transistor and a second transistor of a first conductivity type; a second differential pair having a third transistor and a fourth transistor of a second conductivity type; an output stage having a fifth transistor and a sixth transistor; a first active load having two outputs and a switch, adapted to convert differential outputs from the first differential pair to a single output on either one of said outputs thereof; a second active load having two outputs and a switch, adapted to convert differential outputs from the second differential pair to a single output on either one of said outputs thereof; a first bias circuit having a switch, adapted to select one of two outputs of the first active load to bias the fifth transistor; a second bias circuit having a switch, adapted to select one of two outputs of the second active load to bias the sixth transistor; a first switch adapted to couple output terminal of said output stage to one of control terminals of each of the first and second differential pairs; a second switch adapted to couple an input terminal to another of control terminals of each of the first and second differential pairs.