A new CMOS buffer amplifier design used in low voltage MEMS interface circuits

To achieve low voltage high driving capability with quiescent current control, a class-AB CMOS buffer amplifier using improved quasi-complementary output stage and error amplifiers with adaptive loads is developed. Improved quasi-complementary output stage enables it more suitable for low voltage applications, while adaptive load in error amplifier is used to increase the driving capability and reduce the sensitivity of the quiescent current to fabrication process variation. The circuit has been fabricated in 0.8 μm CMOS process. With 300 Ω load in a ±1.5 V supply, its output swing is 2.42 V. The mean value of quiescent current for eight samples is 204 μA, with the worst deviation of 17%.