Operational amplifier for stably driving a low impedance load of low power consumption

Abstract

An operational amplifier is equipped at its input stage with a folded cascode type differential amplifier and at its downstream stage with pre-buffers, which include a differential amplification stage of PMOS input and a differential amplification stage of NMOS input, as level shifters. A MOS resistor having its gate terminal fed with an intermediate bias potential between a supply voltage V.sub.DD and an earth potential is connected between every one of the drain terminals of current-mirror connected load MOSFETs in the pre-buffers. As a result, the gains of the pre-buffers in the steady state can be suppressed to about 10 dB or less. The individual MOSFETs of the push-pull output stage are individually driven by the pre-buffers of low gains.

Dependencies are inferred from the claim text.