Inverter-based ultra low voltage differential amplifiers

This paper presents a new approach to design ultra low voltage fully-differential amplifiers, using CMOS inverter as a basic design element. With this technique, various circuit topologies, easily scalable to meet different constraints, were derived. Taking also the advantage of the full device control offered by a triple well technology, such amplifiers may be designed to operate at very low supply voltages. Three amplifier topologies, operating rail-to-rail at 0.6V supply voltage, are presented. These circuits were designed in a triple-well 0.18μm CMOS process with Vth_{n, p} ≈ 0.4V and are intended for use in ultra low voltage delta-sigma modulators.