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A Method of Using Negative Resistance to Increase Gain of Operational Amplifier

A technology of negative resistance and operational amplifier, which is applied in the direction of gain control, amplification control, electrical components, etc., to achieve the effect of ensuring stability

Active Publication Date: 2018-03-20
WUXI BIXUN TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to meet the higher and higher gain requirements, the design needs larger device size and higher power consumption, which is obviously intolerable in current low power applications

Method used

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  • A Method of Using Negative Resistance to Increase Gain of Operational Amplifier
  • A Method of Using Negative Resistance to Increase Gain of Operational Amplifier
  • A Method of Using Negative Resistance to Increase Gain of Operational Amplifier

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Embodiment Construction

[0035] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0036] like figure 2 Shown is the operational amplifier structure diagram of the present invention. At the output of the first stage of the op amp, add such as image 3 Negative resistance unit shown. The negative resistance unit includes a pair of NMOS transistors, and the cross-coupling constitutes positive feedback, so the output impedance is negative. Suppose the output impedance of the op amp itself is r 0 , the output impedance of the negative resistance unit is -1 / g m , then the overall output impedance of the op amp after adding the negative resistance unit is:

[0037]

[0038] It can be seen that in guaranteeing g m r 0 Under the condition of m The selection can increase the output impedance by any multiple.

[0039] However, when g m r 0 When ≥1, the op amp no longer works in a stable state. Therefore, considering t...

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PUM

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Abstract

The invention provides a method for improving the gain of the operational amplifier by using negative resistance. A negative resistance unit composed of multiple cross-coupled NMOS differential pairs is added to the output of the first stage of the operational amplifier. Each pair of differential pairs is controlled by the on-chip operational amplifier gain detection. The N-bit operational amplifier negative resistance unit control signal SW generated by the loop controls whether the source end of the NMOS transistor is grounded. In this way, the value of the negative resistance can be controlled according to specific conditions during the use of the chip, so that the target gain value can be achieved on the premise of ensuring the stability of the operational amplifier. The invention does not increase power consumption additionally, and is of great significance to low power consumption design.

Description

technical field [0001] The invention belongs to the field of operational amplifier design and relates to a method for increasing the gain of operational amplifiers by using negative resistance. Background technique [0002] High-gain operational amplifiers have a wide range of requirements in feedback systems. Taking high-precision pipelined analog-to-digital converters as an example, high-gain operational amplifiers in the pipeline stage are an important condition to ensure conversion accuracy. In order to increase the gain of the op amp, a two-stage op amp with gain bootstrap is a commonly used op amp structure, such as figure 1 shown. In order to meet the higher and higher gain requirements, larger device sizes and higher power consumption are required in the design, which is clearly unbearable in current low-power applications. Contents of the invention [0003] The invention provides a method for increasing the gain of the operational amplifier by utilizing the nega...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03G3/20
Inventor 丁洋任咏林
Owner WUXI BIXUN TECH
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