Abstract

The present invention relates to an operational amplifier (1) of class AB including a core (2) of the OTA type which comprises: - first and second input transistors (M1, M2) being inserted between first and second internal nodes (A, B), respectively, and a first common node (X1) and having respective control terminals connected to first and second differential input terminals (IN-, IN+); first and second input stage load transistors (M3, M4) being diode connected and inserted between a first voltage reference (Vdd) and the first and second internal nodes (A, B), respectively; - first and second output transistors (M6, M8) being inserted, in series to each other, between the first voltage reference (Vdd) and a second voltage reference (GND) and being interconnected at an output terminal (OUT) of the operational amplifier (1), the first output transistor (M6) having a control terminal connected to a control terminal of the second input stage load transistor (M4); and - a tail current generator (G1) being inserted between the first common node (X1) and the second voltage reference (GND); the operational amplifier (1) further comprising an adaptive bias block (3) inserted between the first and second voltage references (Vdd, GND) and connected to the first common node (X1) of the core (2). Advantageously according to the invention, the operational amplifier (1) further comprises a positive feedback network (7) inserted between the first voltage reference (Vdd) and the first and second internal nodes (A, B).