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Pre-stage circuit and operational amplifier

A technology of operational amplifiers and circuits, applied in the field of operational amplifiers, can solve problems such as failure to work and performance impact of operational amplifiers

Active Publication Date: 2019-11-05
SHANGHAI AWINIC TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Under the premise of maintaining the tail current of switch N1 and switch N2 equal to IB, as the common mode level of the input signal decreases, switch N0 will finally enter the linear region, then the tail current of switch N1 and switch N2 will decrease, The performance of the op amp will suffer or even fail to work

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  • Pre-stage circuit and operational amplifier
  • Pre-stage circuit and operational amplifier

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Embodiment Construction

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0028] In the prior art, in order to improve the common-mode input range of the operational amplifier, the following improvements have been made to the prior art solution:

[0029] Existing improvement 1, some researchers will use a lower threshold MOS tube or replace it with a new process, which means that the threshold of the switch tube N1 and switch tube N2 is reduced, thereby reducing the lowest level of the common-mode input voltage. But this means an in...

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Abstract

A pre-stage circuit and an operational amplifier are provided, the pre-stage circuit is applied to the operational amplifier and comprises a bias circuit input stage circuit; the bias circuit includesa current source, a first swithching tube, wherein the first end of the first switching tube is connected with the input end of the input stage circuit, the second end of the first switching tube isgrounded, and the control end of the first switching tube is connected with the output end of the current source; a second switching tube, the second end of the second switching tube is grounded, andthe control end of the second switching tube is connected with the output end of the current source; a third switching tube, the second end of the third switching tube is connected with the first endof the second switching tube, the first end of the third switching tube is connected with the output end of the current source, and the control end of the third switching tube is connected with the VPend of the operational amplifier; a fourth switching tube, the second end of the fourth switching tube is connected with the first end of the second switching tube, the first end of the fourth switching tube is connected with the output end of the current source, the control end of the fourth switching tube is connected with the VN end of the operational amplifier, and the common-mode input rangeof the operational amplifier is widened.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a pre-stage circuit capable of improving the common-mode input range of an operational amplifier and an operational amplifier using the pre-stage circuit. Background technique [0002] An operational amplifier is a commonly used analog device, which is mainly used for signal detection, amplification, calculation, etc. Common-mode input Common-mode range is one of the specifications of an operational amplifier. The input range of the common-mode voltage has a lot to do with the architecture of the operational amplifier, especially the input stage of the operational amplifier. When NMOS is used as the operational amplifier differential pair tube as the input stage, the lower limit of the common-mode voltage will be limited by the NMOS threshold and the tail current source NMOS. [0003] Traditional operational amplifier (referred to as operational amplifier) ​​input s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F1/02H03F3/16
CPCH03F1/02H03F3/165Y02D30/70
Inventor 何永强罗旭程程剑涛杜黎明孙洪军乔永庆
Owner SHANGHAI AWINIC TECH CO LTD
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