System and method for reducing noise of tunnel magnetoresistance sensor

A technology of sensor noise and tunnel magnetoresistance, applied in instruments, measuring magnetic variables, measuring devices, etc., can solve problems such as poor noise reduction effect, achieve good noise reduction effect, improve signal-to-noise ratio, and low power consumption

Active Publication Date: 2020-07-14
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the above defects or improvement needs of the prior art, the present invention provides a system and method for reducing the noise of the tunne

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  • System and method for reducing noise of tunnel magnetoresistance sensor
  • System and method for reducing noise of tunnel magnetoresistance sensor
  • System and method for reducing noise of tunnel magnetoresistance sensor

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Embodiment 1

[0036] A system for reducing noise in tunneling magnetoresistive sensors such as figure 1 As shown, it includes: a non-coil shielding cylinder 1 and a drive circuit 2; wherein, the material of the non-coil shielding cylinder 1 is a high permeability soft magnetic material, that is, a soft magnetic material with a relative permeability greater than 5000. In this embodiment, the soft magnetic material with high magnetic permeability is 1J85 type permalloy, and its magnetic permeability will increase and even be saturated under the influence of a weaker magnetic field; , its magnetic permeability will enter the saturation region and decrease with the increase of the induced magnetic field, and the corresponding magnetic shielding ability will also decrease. There are circuit connection points on the non-coil shielding cylinder 1, which can be connected to high-frequency alternating current to realize high-frequency variation of shielding performance, and is wrapped with insulatin...

Embodiment 2

[0042] A method for reducing the noise of a tunnel magnetoresistive sensor, comprising the steps of:

[0043] S1. Place the TMR sensor to be processed in the center of the non-coil shielding cylinder;

[0044] S2. Pass AC current to the non-coil shielding cylinder. Based on the supersaturation characteristics of the high permeability soft magnetic material of the non-coil shielding cylinder, its shielding ability will undergo high-frequency changes, thereby reducing the DC magnetic field to be measured outside the shielding cylinder. Transform into a high-frequency AC magnetic field to reduce the 1 / f noise of the TMR sensor;

[0045] S3. By performing phase-sensitive detection and low-pass filtering on the AC output of the TMR sensor, the sum-frequency signal is filtered out, and the difference-frequency signal is retained, so as to further filter out the 1 / f noise of the TMR sensor.

[0046] Further, the TMR sensor is placed in the center of the non-coil shielding cylinder, ...

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Abstract

The invention discloses a system and a method for reducing noise of a tunnel magnetoresistance sensor. The system comprises a coil-free shielding cylinder and a driving circuit, wherein the coil-freeshielding cylinder is made of a soft magnetic material with high magnetic conductivity; a to-be-processed TMR sensor is placed in the center of the coil-free shielding cylinder; the output end of theTMR sensor is connected with the input end of the driving circuit; the coil-free shielding cylinder is based on the supersaturation characteristic of a high-permeability soft magnetic material, and when alternating current is introduced, the shielding capability of the coil-free shielding cylinder changes at high frequency, so that a to-be-measured direct-current magnetic field of the TMR sensor is converted into a high-frequency alternating-current magnetic field, and 1/f noise of the TMR sensor is reduced; the driving circuit performs phase-sensitive detection and low-pass filtering on an output signal of the TMR sensor based on the reference signal, filters out a sum frequency signal, retains a difference frequency signal, and further filters out 1/f noise of the TMR sensor. According to the coil-free shielding cylinder, multiple turns of coils do not need to be wound, new noise cannot be introduced, and the noise reduction effect is good.

Description

technical field [0001] The invention belongs to the field of magnetic sensor noise reduction, and more specifically relates to a system and method for reducing noise of a tunnel magnetoresistance sensor. Background technique [0002] Tunneling Magneto Resistive (TMR) is a magnetic field measurement sensor with high sensitivity, high response frequency, and low power consumption. application. TMR sensor has many advantages, but the noise is relatively large, so it is of great significance to study a method to reduce the noise of tunnel magnetoresistive sensor. [0003] Existing methods for reducing the noise of tunnel magnetoresistive sensors include sigma-delta circuit modulation method, magnetic tunnel junction array method, MEMS type magnetic flux modulation method and magnetic shield chopper modulation method. Among them, the sigma-delta circuit modulation reduces noise through oversampling and noise shaping techniques, but the multi-order sigma-delta circuit has a comp...

Claims

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Application Information

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IPC IPC(8): G01R33/09G01R1/18
CPCG01R1/18G01R33/098
Inventor 欧阳君李佳旭杨晓非陈实姚行中徐俊周晓华
Owner HUAZHONG UNIV OF SCI & TECH
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