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Low-offset operational amplifier

An operational amplifier and amplifying circuit technology, applied in amplifiers, amplifier combinations, differential amplifiers, etc., can solve problems such as reducing the gain of operational amplifiers

Inactive Publication Date: 2016-03-16
INSPUR BEIJING ELECTRONICS INFORMATION IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The circuit system will cause offset due to some circuit structure reasons. The traditional suppression method is to replace the first-stage differential amplifier circuit with a completely symmetrical symmetrical differential amplifier circuit. The advantage of this method is that it can effectively reduce the offset, but the disadvantage is that the operation The gain of the amplifier becomes smaller

Method used

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Embodiment 1

[0027] Please refer to figure 1 , figure 1 A structural schematic diagram of a low offset operational amplifier provided by the present invention, the low offset operational amplifier includes:

[0028] A first-stage differential amplifier circuit 1, a symmetrical differential amplifier circuit 3, a symmetrical signal generating circuit 2, and a second-stage symmetrical output amplifier circuit 4, wherein:

[0029] The output end of the first-stage differential amplifier circuit 1 is connected to the first input end of the symmetrical differential amplifier circuit 3, and the first-stage differential amplifier circuit 1 is used to amplify the input signal to obtain a first-stage amplified voltage and output it to the first input end;

[0030] The second input end of the symmetrical differential amplifier circuit 3 is connected to the output end of the symmetrical signal generating circuit 2; wherein, the symmetrical signal generating circuit 2 is used to generate a symmetrica...

Embodiment 2

[0037] Please refer to figure 2 , figure 2 A schematic structural diagram of another low-offset operational amplifier provided by the present invention. On the basis of Embodiment 1, the low-offset operational amplifier:

[0038] Preferably, the primary differential amplifier circuit 1 specifically includes a first PMOS, a second PMOS, a third PMOS and an active load circuit, wherein:

[0039] The source of the third PMOS is connected to the power supply, the gate of the third PMOS is connected to the bias voltage, the drain of the third PMOS is respectively connected to the sources of the first PMOS and the second PMOS, and the gate of the first PMOS is connected to the source of the first PMOS. The negative pole of the input signal, the drain of the first PMOS is connected to the first end of the active load circuit, the gate of the second PMOS is connected to the positive pole of the input signal, and the drain of the second PMOS is used as the output terminal of the fir...

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Abstract

The invention discloses a low-offset operational amplifier. The low-offset operational amplifier comprises a first-stage differential amplification circuit, a symmetrical differential amplification circuit, a symmetrical signal generation circuit and a second-stage symmetrical output amplification circuit, wherein the output end of the first-stage differential amplification circuit is connected with the first input end of the symmetrical differential amplification circuit; the second input end of the symmetrical differential amplification circuit is connected with the output end of the symmetrical signal generation circuit; and the output end of the symmetrical differential amplification circuit is connected with the second-stage symmetrical output amplification circuit. According to the low-offset operational amplifier provided by the invention, the symmetrical differential amplification circuit symmetrical to the first-stage differential amplification circuit is introduced at the rear of the first-stage differential amplification circuit of the low-offset operational amplifier; therefore, on the premise that enough gain of the first-stage differential amplification circuit is ensured, offset voltage due to asymmetry of the first-stage differential amplification circuit is eliminated through the symmetrical differential amplification circuit symmetrical to the first-stage differential amplification circuit; and thus, the low-offset operational amplifier has relatively high gain while offset voltage is eliminated.

Description

technical field [0001] The invention relates to the technical field of operational amplifiers, in particular to a low offset operational amplifier. Background technique [0002] An ideal operational amplifier, when the input voltage is 0, the output voltage should also be 0. But in fact, in the prior art, its differential input stage is difficult to achieve complete symmetry. Usually, when the input voltage is 0, there is a certain output voltage, and this output voltage is usually called an offset voltage. The offset voltage of the operational amplifier is a very important parameter to measure the performance of the operational amplifier. Excessive offset voltage will increase proportionally when the operational amplifier amplifies the signal, which will seriously affect the accuracy of the operational amplifier. The offset voltage is mainly generated by the process and the circuit system. The circuit system will cause offset due to some circuit structure reasons. The tra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F3/68H03F3/45
CPCH03F3/45071H03F3/68
Inventor 王硕唐涛石广刘海林
Owner INSPUR BEIJING ELECTRONICS INFORMATION IND
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