A 1.5 V class AB CMOS buffer amplifier for driving low-resistance loads

Few CMOS opamps that can operate on a single 1.5 V supply have been reported to date, although there is no lack of potential applications. Existing 5 V opamp designs require use of cascode and stacked transistors and consequently are not suited for operation at 1.5 V. A design technique for 1.5 V CMOS opamps has been outlined by Eschauzier et al. (see ISSCC Digest of Technical Papers, p. 246-7, Feb., 1994). The resulting circuit, a four-stage class AB opamp, is complex and data concerning the opamp performance in case of significant resistive or capacitive loads are lacking. The 1.5 V class AB CMOS opamp presented here has a less complex architecture and experimental results demonstrate capability of driving heavy resistive loads with low distortion.