Low voltage operational amplifier based on CMOS (complementary metal oxide semiconductor) process

Abstract

The invention relates to a low voltage operational amplifier based on the CMOS (complementary metal oxide semiconductor) process. The low voltage operational amplifier comprises three bias current setting PMOS (positive channel metal oxide semiconductor) tubes, a PMOS differential input pair, two current mirrors constituted by NMOS (negative channel metal oxide semiconductor) tubes, a current mirror constituted by the PMOS tube and two level shift PMOS tubes working in a sub-threshold region. The low voltage operational amplifier has novel structure and simple circuit, and can eliminate the limitation that the threshold voltage of an NMOS device needs to be larger than emitter-base voltage VEB (on) of a parasitic PNP tube and be implemented by adopting any threshold standard CMOS process. The working voltage of a circuit is lower than 1V, the required quiescent current is small, and the two do not change along with the temperature basically. The low voltage operational amplifier can be widely applied in the field of analog integrated circuits with the working voltage of below 1V, in particular to Sub-1-V CMOS bandgap reference source circuits.

Description

Technical field [0001] The invention relates to a low-voltage operational amplifier, in particular to a low-voltage operational amplifier based on CMOS technology. Its direct application field is low-voltage analog integrated circuits, especially Sub-1V CMOS bandgap reference source circuit. Background technique [0002] Low voltage and low power consumption are two important development trends in analog integrated circuit design. More and more integrated circuit systems will work under a single power supply voltage below 1V. Sub-1V CMOS bandgap reference is one of the core units of analog integrated circuits whose power supply voltage is lower than 1V, and low-voltage operational amplifiers whose working voltage is lower than 1V directly determine the performance of the Sub-1V CMOS bandgap reference. [0003] Conventional low-voltage operational amplifiers used for sub-1V bandgap references usually either need to use a special process or have certain requirements for process para...

AI Technical Summary

Problems solved by technology

When the threshold voltage of the NMOS transistor is less than a V EB (on), M N1a and M N2a The drain-to-source voltages will be less than their respective overdrive voltages, making M N1a and M N2a Working in the linear region, not the saturation region, will lead to an increase in the quiescent current of the entire operational amplifier

This phenomenon is especially obvious at low temperatures, because at low temperatures, the threshold voltage of NMOS usually increases less than V EB (on) increases with decreasing temperature, resulting in M N1a and M N2a The drain-source voltage becomes smaller and further enters the linear region, making the performance parameters of the operational amplifier (such as input offset, quiescent current, etc.) worse, thus significantly affecting the performance of the bandgap reference circuit

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