A 0.7-V rail-to-rail buffer amplifier with double-gate MOSFETs

This paper proposes a 0.7-V rail-to-rail amplifier with double-gate MOSFETs, which are possible candidates for CMOS technology nodes beyond 22nm. The back-gate of the input transistors are used to keep them on, which allows the inputs at the front gates to be varied from rail to rail. Unlike conventional rail-to-rail architectures, which require two differential pairs to achieve rail-to-rail input common-mode range, the unique properties of the double-gate transistor allow only one input differential pair to be used, thus making this a first rail-to-rail amplifier of its kind. The amplifier achieves a dc open-loop gain of 88 dB, a unity-gain frequency of 28 MHz with a phase margin of 63° at a load capacitance of 10 pF, and a dc power consumption of 80 μW.