A single-stage differential operational amplifier including an input stage formed by a pair of input transistors having control terminals connected to a respective first and second input, first conduction terminals coupled to a respective first and second output and second conduction terminals coupled to receive a polarization current. An output stage is formed by a pair of output transistors in diode configuration and having control terminals coupled to a relative first conduction terminal and connected to a respective first and second output, and second conduction terminals connected to a reference line. A coupling stage is interposed between the first conduction terminals of the output transistors and the first and second outputs to define the diode configuration of the output transistors and a gain value of the operational amplifier.