Operational amplifier with increased common mode input range

摘要

An operational amplifier includes a first stage with a first differential transistor pair inputting a differential input signal at their gates, a first tail current source transistor connected to sources of the first differential transistor pair, and a load transistor pair connected in series with the drain of first differential transistor pair. An input stage includes a second differential transistor pair connected to respective drains of the first differential transistor pair at their gates, and a second tail current transistor connected to sources of the differential transistor pair. An output stage outputs a signal corresponding to the differential input signal.