A 1.2V, 200 µ W rail-to-rail Op Amp with 90dB THD using replica gain enhancement

This paper presents an architecture for a high-swing 1.2 V low-power fully differential class-AB amplifier with a DC-gain of 52 dB. A low-voltage differential input stage is applied as the basic architecture. The replica gain enhancement technique is used to increase the DC-gain by 20 dB without degrading the output swing. Furthermore, this gain enhancement concept does not increase the minimal supply voltage and also allows scaling of the replica amplifier. The power dissipation is 200 µW providing a gainbandwidth (GBW) of 1.9 MHz at a capacitive load of 30 pF and a THD of 90 dB.