Rail-to-rail input stage with current compensation function

A technology of current compensation and input stage, which is applied in the direction of DC-coupled DC amplifiers and differential amplifiers, and can solve problems affecting amplifier performance, output stage output offset, etc.

Inactive Publication Date: 2012-02-15
FUDAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The direct result of this change in DC current is that there is an output offset in the output stage, that is, the output DC level will change with the input common-mode level, thereby affecting the performance of the amplifier.

Method used

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  • Rail-to-rail input stage with current compensation function
  • Rail-to-rail input stage with current compensation function
  • Rail-to-rail input stage with current compensation function

Examples

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Embodiment Construction

[0013] The present invention is further described in detail by a specific example below.

[0014] figure 2 A complete circuit diagram of an amplifier using a rail-to-rail input stage with current compensation is given. Among them, the variable current source is realized by transistors Mco1~Mco12. The output stage is a folded cascode stage, which is composed of transistors MC1~MC8.

[0015] When the input common-mode level is the middle level, the input transistors M1, M2, M3, and M4 are turned on at the same time, and only MB3 and MB6 are turned on in the triple current mirror tubes, and the current magnitude is 2I0. At this time, since the triple current mirror tube MB4 has no current, the variable current source tubes Mco9 and Mco10 as its current mirror also have no current, and the gate voltage of Mco9, that is, Vco1 is high, so the variable current source tubes Mco1~Mco4 All off. Similarly, since the triple current mirror tube MB1 has no current, the variable current...

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Abstract

The invention belongs to the technical field of analogue circuit designing, and particularly discloses a rail-to-rail input stage with a current compensation function. The rail-to-rail input stage is formed by connecting four input differential tubes, eight triple current mirrors and eight compensation variable current sources by a circuit. The rail-to-rail input stage realizes current compensation under different input common mode levels by utilizing the variable current sources to make direct current extracted from a post stage unrelated with the input common mode levels, thereby reducing the output imbalance of the post stage.

Description

technical field [0001] The invention belongs to the technical field of analog circuit design, and in particular relates to an input stage of an amplifier in an analog circuit. Background technique [0002] In analog circuits, the common-mode level of the signal is often uncertain, so the range of possible signal common-mode levels can be as large as the negative power supply voltage to the positive power supply voltage. To handle signals with different common-mode levels, the rail-to-rail input stage is an important part of the amplifier. [0003] In practical applications, in order to keep the transconductance of the overall input stage constant at different input common-mode levels, it is usually necessary to give different DC currents to the input transistors at different input common-mode levels. Since the current is directly extracted from the output stage of the subsequent stage by the input stage, the DC current of the output stage changes when the input common-mode ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F3/45
Inventor 李一雷谈熙闫娜闵昊
Owner FUDAN UNIV
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