Design of a low-voltage rail-to-rail input and output operational amplifier with nested Miller compensation

Abstract

A rail-to-rail constant g m input and class-AB output operational amplifier in a 0.8-μm double-poly, double-metal, n-well technology operating at a low supply voltage of 3.3V is presented. A technique that uses nested Miller compensation yields 130 dB de gain and 3.5 MHz unity gain frequency at a 10-kΩ and 10-pF load. The class-AB output provides efficient quiescent current control and delivers output current to 1-kΩ resistive load with low total harmonic distortion less than 0.1%. The die area of the operational amplifier is 0.15 mm 2.