Operational amplifier with rail-to-rail common-mode input and output range

摘要

An operational amplifier with a rail-to-rail common-mode input and output range comprises a differential input stage consisting of a first differential pair and a second differential pair for receiving an input signal; a summing circuit coupled to the differential input stage for outputting a summation result of the output signals of the first differential pair and second differential pair; and a push-pull output stage coupled to the summing circuit for outputting an amplified signal comprising an output terminal for outputting the amplified signal, a source coupled transistors for generating a control voltage according to output current of the summing circuit, and a first output transistor and a second output transistor for controlling current of the first output transistor and the second output transistor according to the control voltage of the source coupled transistor.