Integrated high-accuracy triaxial magnetic sensor

Abstract

An integrated high-accuracy triaxial magnetic sensor comprises four magnetic measuring units, a signal-output and offset electrode, an inner plane accumulator, four magnetic orbital transfer accumulators, four pits and a basement. The inner plane accumulator adopts a symmetrical structure and is arranged in the middle of the basement, the four magnetic orbital transfer accumulators are arranged at four sides of the plane accumulator in a symmetrical mode, and each magnetic orbital transfer accumulator is arranged in a pit. Each magnetic measuring unit comprises a Wheatstone bridge formed by two giant magneto resistive (GMR) sensitive elements and two GMR reference elements. The integrated high-accuracy triaxial magnetic sensor has the advantages of being simple and compact, small in size, convenient to manufacture, low in manufacturing cost, and high in sensitivity and the like.

Description

technical field [0001] The invention mainly relates to the technical field of weak signal sensing, in particular to an integrated high-precision three-axis magnetic sensor. Background technique [0002] Weak magnetic field measurement is widely used in geomagnetic navigation, target detection, geological exploration, biomedicine and other fields. The three-axis magnetic sensor can measure the three components of the magnetic field at the same time, and calculate the inclination and azimuth of the sensor. Low power consumption and miniaturization are the main development directions of three-axis magnetic sensors. [0003] At present, there are many types of three-axis magnetic sensors used for magnetic field measurement. According to the implementation method, they can be divided into assembled type and integrated type. According to their working principles, they can be divided into fluxgate sensors, Hall sensors, Lorentz force magnetic sensors, GMR (Giant Magnetoresistive,...

AI Technical Summary

Problems solved by technology

2. The sensor for measuring the Z-direction magnetic field in the vertical plane is placed on the slope, and the three-axis measurement is realized together with the in-plane sensors for measuring the X and Y-direction magnetic fields (patent numbers: US7564237, US7126330), which realizes integrated production, but the slope The MR magnetic sensor on the surface is relatively difficult to manufacture, and the consistency with the in-plane magnetic sensor is difficult to guarantee

4. Another person uses CMOS technology to realize a three-axis magnetic field sensor based on the Hall effect on a silicon chip, which ensures the orthogonality between the three axes, no hysteresis effect, and does not require special magnetic materials, and can be measured simultaneously Three components, but the resolution is low, about 21μT

5. Using micromachining technology to use thermal stress on the GaAs substrate to make the manufactured Hall sensor roughly perpendicular to the substrate plane to form a three-axis Hall sensor, which realizes the miniaturization and integrated design and manufacture of the three-axis magnetic sensor, and the process flow is relatively Simple, but it is difficult to accurately control the angle between the Z-direction sensor and the plane, and it is difficult to guarantee the orthogonality between all three axes, and the minimum detectable value is around 2μT

6. Someone used the principle of changing the output of the piezoresistive sensitive element by using the interaction force between the permanent magnet film and the external magnetic field, and used MEMS processing technology to realize the integrated design of the three-axis magnetic sensor on the silicon chip, ensuring the miniaturization and integration of the sensor , but the resolution that can be achieved is limited. At present, the measurement resolution of its Z-direction magnetic field is 250nT

7. Since the current-carrying conductor placed in the magnetic field will be subjected to the force of the Lorentz force, this force will be displaced through structural design, causing a change in capacitance, and the magnetic field value can be obtained by measuring the capacitance. The Lorentz force using MEMS technology Zili three-axis magnetic sensor has no hysteresis effect and does not require special magnetic materials. It can guarantee orthogonality, miniaturization, and low power consumption. However, the resolution achieved by this principle of magnetic sensor is not high. At present, The measurement resolution of the Z component is about 70nT, which is lower than the resolution of the in-plane magnetic field measurement

[0007] In general, the integrated three-axis magnetic sensor has better orthogonality than the assembled type, and the miniaturization of the sensor can be realized by using micromachining technology, but based on Hall elements, AMR elements, and Lorentz force resonance magnetic sensitive elements, The overall resolution is low; using GMR as a sensitive element can generally achieve higher sensitivity and resolution, but GMR is sensitive to the magnetic field in the plane, and the magnetic field in the vertical plane has little effect on it

Placing a soft magnetic block near the GMR sensitive element can transfer the Z-direction magnetic force lines to the plane for measurement to a certain extent, but the above various placement methods are difficult to implement in practice, and it is difficult to ensure the structural symmetry and Consistency of performance; making the GMR sensitive element on the slope of the sensor substrate can directly measure the Z-direction magnetic field, but its implementation method is also relatively complicated, and the distance between the magnetic sensors located on the slope and between the magnetic sensors in the plane Consistency is also difficult to guarantee

Therefore, the difficulty of technology development in the prior art lies in how to use GMR sensitive elements to measure the Z-direction magnetic field. This difficulty makes it difficult to realize the design and manufacture of a three-axis integrated magnetic sensor based on GMR sensitive elements.

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