A rail-to-rail operational amplifier switchable to comparator mode

Abstract

The invention discloses a rail-to-rail operational amplifier capable of being switched into a comparator mode. The rail-to-rail operational amplifier comprises a working mode control circuit, a biasing circuit, a rail-to-rail input circuit, a latch comparison circuit, a gain amplification circuit, an AB type output circuit and a frequency compensation circuit. According to the invention, switchingbetween an operational amplifier mode and a comparator mode can be realized; rail-to-rail input and output are realized; the operational amplifier mode adopts multi-stage cascade connection, the gainis very high, the frequency compensation circuit has a multi-stage compensation function, and the stability of the circuit can be improved; the comparator mode has multi-stage cascade connection andhas high precision, and the disconnection frequency compensation circuit and the intermediate stage adopt latch structures, so that the speed of the comparator is greatly improved; the comparator modeand the operational amplifier mode share the rail-to-rail input circuit and the AB type output circuit, so that circuit elements, areas and costs can be greatly reduced, and the operational amplifieris particularly suitable for microminiature and low-power-consumption applications.

Description

technical field [0001] The invention relates to a rail-to-rail comparator and a rail-to-rail operational amplifier, in particular to a rail-to-rail operational amplifier switchable to a comparator mode. Background technique [0002] As the most basic device in analog integrated circuits, operational amplifiers determine the performance of systems such as digital-to-analog / analog-to-digital converters. As a key module of analog-to-digital conversion circuits, comparators also play an important role in the performance of analog-to-digital conversion circuits influences. [0003] In order to improve the versatility of the module, sometimes it needs to work in the operational amplifier mode, and sometimes it needs to work in the comparator mode, but if the operational amplifier is simply used as a comparator, the speed of the circuit will be greatly reduced. If an operational amplifier and a comparator are used at the same time, it will Increasing the number of components, area...

AI Technical Summary

Problems solved by technology

[0003] In order to improve the versatility of the module, sometimes it needs to work in the operational amplifier mode, and sometimes it needs to work in the comparator mode, but if the operational amplifier is simply used as a comparator, the speed of the circuit will be greatly reduced. If an operational amplifier and a comparator are used at the same time, it will Increase the number of components, area and cost of integrated circuits, which will be severely limited in micro-miniature applications

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