High-Speed Operational Amplifiers Based on the Advanced Derivatives of the Class AB Intermediate Stage

Abstract

In this paper, the circuitry of the AB class intermediate stage for fast-acting Op-Amps, including those on CMOS and arsenide-gallium transistors, which allows to significantly increase the SR of Op-Amos, is developed. The purpose and novelty of the present paper is to investigate new structures of intermediate stages (ISs), which complement known publications on problems of increasing the speed response of Op-Amps. To achieve the aim the drawbacks of a very popular in automation and measurement devices architecture of an operational amplifier (Op-Amp) with a IS based on a "folded" cascode have been considered. As an example, the paper gives one of them - a nonlinear mode of operation of the IS, which does not allow to provide a large current overcharge correction capacitor Op-Amp, which has a negative impact on the maximum rate of increase of the output voltage (SR). In conclusion of article, results of computer simulation of static modes and dependence of output currents of IS on input voltage in environment LTSpice are discussed, showing, that the relation of maximum output current of IS to its current in a static mode exceeds two orders, that has positive influence on SR.