Operational amplifier with offset voltage centering, and low-voltage compatible

The present invention relates to integrated circuits, and, more particularly, to an operational amplifier that operates at a low supply voltage and has a low offset voltage. An operational amplifier includes an input stage, and a level-transforming stage with first and second arms. Each arm has at least one bipolar transistor. Input transistors are connected to the input stage and are connected together by their bases. At least one gain stage is connected to the transistor of the second transforming arm. A current terminal of the transistor on the first transforming arm is connected to its base by a bypass arm. In addition, the amplifier has a centering transistor connected by its base to the transistors on the arms of the transforming stage for controlling a current which conducts through the bypass arm.