A composite three-axis Hall sensor based on acoustic wave excited magnetoelectric antenna

Abstract

The present invention provides a composite three-axis Hall sensor based on an acoustic wave excitation magnetic antenna, comprising a Hall probe and an acoustic wave excitation magnetoelectric antenna; the acoustic wave excitation antenna is applied to a three-axis Hall sensor to form a composite three-axis Hall sensor, the frequency band of a low-frequency signal to be measured is transferred to a higher frequency band through the acoustic wave excitation antenna, and the magnetic field signal to be measured in the output signal of the Hall probe of the three-axis Hall sensor is restored through a demodulation circuit; the noise power spectral density of the Hall probe in the higher frequency band is low, and the sensor noise is reduced by frequency transfer. The present invention transfers the frequency of the signal to be measured to a higher frequency by modulation and demodulation, and the noise power spectral density at the high frequency is low, so the noise sensitivity of the probe can be improved.

Description

Technical Field

[0001] The invention belongs to the field of sensor technology, and in particular relates to a composite three-axis Hall sensor based on an acoustic wave excited magnetoelectric antenna. Background Art

[0002] High-sensitivity magnetic field sensors are widely used in positioning, navigation, timing (PNT), detection and automation information technology. Magnetic field sensors suitable for civilian-grade PNT have the following seven characteristics: planar structure; high sensitivity; out-of-plane vector; small size and light weight; low power consumption; mass production; clear physical mechanism. Existing magnetic field sensors include inductive, fluxgate, optical pump, giant magnetoresistance, giant magnetoimpedance, Hall probe and other types. However, the widely used three-axis magnetic field sensors are mainly three-axis Hall sensors such as those disclosed in the MLX90422 patent.

[0003] Most existing magnetic field sensors cannot meet these conditions at the same time due to physical mechanisms, which will cause many application limitations. For example, the chip-level optical pump sensor with small size and light weight has high power consumption and causes large energy loss. Another example is the high-sensitivity fluxgate magnetic field sensor. Its excitation and receiving coils will produce out-of-plane one-axis orientation when integrated in three axes, which makes it difficult to achieve a planar structure and will cause relatively large angle errors. These errors can be partially compensated by subsequent algorithms, but cannot be completely eliminated. The main problem of high-sensitivity inductive sensors is that the size and weight are not suitable for PNT applications, and they have the same problem as fluxgate that they cannot be flattened. Various magnetoresistive sensors (GMR, AMR, TMR) that are slightly different from the working principles of the above sensors have the characteristics of low power consumption, planarization and mass production, but these sensors mainly measure in-plane directions, and the noise is high after miniaturization. The detection method of planar Hall sensors is similar to that of magnetoresistive sensors, and it is impossible to measure magnetic fields in out-of-plane directions.

[0004] The three-axis Hall sensor uses more than four Hall sensors integrated in a plane to assist with the field collector to complete the measurement of the three-axis magnetic field. The magnetic field in the out-of-plane Z-axis direction is measured by the traditional Hall effect, and the in-plane magnetic field is changed to the out-of-plane direction by the field collector located above the sensor through the magnetic focusing effect, and a relative set of sensors are used for differential measurement to obtain the magnetic field strength in the X and Y directions of the plane respectively. The only drawback of the three-axis Hall sensor is its low sensitivity, and the low-frequency noise level can reach tens to hundreds of nT / rt-Hz. This restricts some of the application scenarios of the sensor. For example, for the application of azimuth calibration in navigation, the sensor needs to have high sensitivity to measure at least two axes. The comparison between Hall sensors and other types of magnetic field sensors is as follows:

[0005]

[0006] The low-frequency detection accuracy of the Hall sensor is low, but its noise power spectral density decreases with increasing frequency. In this way, the magnetic field to be measured can be shifted to the high frequency band using a magnetic field transmitting antenna, and the magnetic field signal in the high frequency band can be converted into an electrical signal by the Hall probe. After demodulation, the low-frequency detection performance of the Hall probe can be improved by 1-2 orders of magnitude. The magnetic field transmitting antenna used in this "fluxgate-Hall" composite sensor is composed of a coil and a ferromagnetic material core with a high magnetic flux coefficient. When the core is wrapped with a coil with a large number of turns, it is difficult to fix the antenna inside the sensor plane; or when the core is inside the plane, it is difficult to wrap a large number of turns. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a composite three-axis Hall sensor based on an acoustic wave excited magnetoelectric antenna, which adopts the following technical solution:

[0008] A composite three-axis Hall sensor based on an acoustic wave excited magnetoelectric antenna comprises a Hall probe and an acoustic wave excited magnetoelectric antenna. The acoustic wave excited antenna is applied to the three-axis Hall sensor to form the composite three-axis Hall sensor. The frequency band of a low-frequency signal to be measured is transferred to a higher frequency band through the acoustic wave excited antenna. Depending on the size of the antenna, this high-frequency carrier frequency band is generally in the range of 30MHz-3GHz. The magnetic field signal to be measured in the output signal of the Hall probe passing through the three-axis Hall sensor is restored to a low frequency band of less than 100kHz through a demodulation circuit. The noise power spectral density of the Hall probe in the higher frequency band is lower, and the sensor noise is reduced through frequency transfer.

[0009] Furthermore, the Hall probe includes a Hall probe HPa, a Hall probe HPb, a Hall probe HPc and a Hall probe HPd; the Hall probes HPa, HPb, HPc and HPd are prepared on the substrate by micro-nano processing and etching; the acoustic wave excited magnetoelectric antenna is in the shape of a cross with two axes of unequal lengths, the center part is fixed on the substrate, and the ends of the two axes are respectively located on the Hall probes HPa, HPb, HPc and HPd; the direction perpendicular to the plane of the substrate is defined as the Z-axis direction, and the Z-axis direction is The magnetic field strength in the X-axis direction is obtained by the common mode components of Hall probes HPa, HPb, HPc and HPd; the direction along the long axis of the acoustic wave excited magnetoelectric antenna is defined as the X-axis, and according to the principle of symmetry, the magnetic field strength in the X-axis direction is obtained by the differential mode components of Hall probes HPa and HPb after demodulation; the direction parallel to the short axis of the acoustic wave excited magnetoelectric antenna is defined as the Y-axis direction, and the magnetic field strength in the Y-axis direction is obtained by the differential mode components of Hall probes HPc and HPd after demodulation; the actual magnetic field strength B in the X, Y and Z axis directions x ,B y ,Bz And the output voltage V of Hall probe HPa, Hall probe HPb, Hall probe HPc, and Hall probe HPd HPa ,V HPa ,V HPa ,V HPa The relationship between is defined by formula (1):

[0010]

[0011] Among them, f(.) is the signal conversion coefficient of the four sets of Hall probes, and g(.) is the signal conversion coefficient of the four sets of antenna-Hall probe composite structures;

[0012] The magnetic field strengths on the X, Y, and Z axes are obtained from formula (1):

[0013]

[0014] Furthermore, the signal amplification and demodulation circuit of the Hall probe includes an antenna excitation signal source, a signal amplification module, a signal demodulation module and a feedback module; the antenna signal excitation source is composed of an oscillator with high frequency stability and low noise, capacitors and resistors, the signal amplification module includes a low-noise voltage operational amplifier circuit, capacitors and resistors, and the signal demodulation module includes a multiplier and a low-pass filter.

[0015] Furthermore, under the action of the alternating voltage of the oscillator, the acoustic wave excited magnetoelectric antenna emits an excitation magnetic field carrier signal from the magnetostrictive phase material in the acoustic wave excited magnetoelectric antenna through the inverse magnetoelectric coupling effect, and at the same time, the low-frequency magnetic field signal to be measured modulates the carrier signal in the acoustic wave excited magnetoelectric antenna, and the modulated magnetic field signal acts on the Hall probe, and the bias voltage source is the power supply of the Hall probe; the output of the Hall probe is connected to the signal amplification module, and the output of the signal amplification module is negatively fed back to the antenna input end through voltage, and at the same time, the output is connected to a multiplier, and the multiplier realizes demodulation of the low-frequency signal, and the output end of the multiplier is connected to a low-pass filter, and the low-pass filter realizes the filtering function of high-order harmonics, and outputs a voltage signal at the output end, and the output signal realizes voltage negative feedback through a feedback resistor.

[0016] Furthermore, the Hall probe is a semiconductor film made of indium antimonide or indium gallium arsenide.

[0017] Furthermore, the acoustic wave excited magnetoelectric antenna is composed of a layer of ferromagnetic material with high magnetostriction and high magnetic permeability and a layer of piezoelectric thin layer.

[0018] Furthermore, the ferromagnetic material is an iron-based amorphous material, an iron-based nanocrystalline magnetostrictive material or a magnetostrictive iron oxide that has undergone a controllable heat treatment process and has undergone changes in surface topology and chemical structure.

[0019] Furthermore, the piezoelectric thin layer is a lead magnesium niobate-lead titanate piezoelectric single crystal or a lead zirconate titanate piezoelectric ceramic with a high electromechanical coupling coefficient.

[0020] Furthermore, by setting the lengths of the acoustic wave excited magnetoelectric antennas in two directions, the two acoustic wave excited magnetoelectric antennas have different mechanical resonance frequencies, thereby avoiding crosstalk of antenna excitation frequencies.

[0021] Furthermore, the Hall probe is a planar magnetic field sensor.

[0022] Beneficial effects:

[0023] The present invention uses an acoustic wave excitation antenna as a magnetic field collecting device of the Hall sensor, which transfers the frequency of the signal to be measured to a higher frequency by means of modulation and demodulation. The noise power spectrum density at the high frequency is low, so the noise sensitivity of the probe can be improved. The present invention can avoid the use of an excitation coil in the signal modulation process, which is beneficial to the planarization of the sensor probe. The three-axis angle error of the planarized sensor is lower than the three-axis detection mode of the physical space. The present invention distinguishes the excitation signal frequencies of the two axes by the size difference between the two axes of the antenna plane, thereby avoiding mutual crosstalk between the two axes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of a composite three-axis Hall sensor based on an acoustic wave excitation antenna of the present invention;

[0025] Figure 2 A schematic diagram of a Hall probe circuit of a composite three-axis Hall magnetic field sensor of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the Hall probe of the composite three-axis Hall magnetic field sensor of the present invention;

[0027] Figure 4 It is a schematic diagram of the magnetoelectric antenna structure of the composite three-axis Hall magnetic field sensor of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The composite three-axis Hall sensor based on acoustic wave excitation magnetic antenna of the present invention comprises four sets of Hall probes, a pair of acoustic wave excitation magnetoelectric antennas and a signal amplification and demodulation circuit. Figure 1As shown, semiconductor films such as indium antimonide and indium gallium arsenide used for Hall sensors are used but not limited thereto. The acoustic wave excited magnetoelectric antenna is composed of a layer of ferromagnetic material with high magnetostriction and high magnetic permeability and a layer of piezoelectric thin layer. The ferromagnetic material can be, but is not limited to, iron-based amorphous, iron-based nanocrystalline magnetostrictive materials, magnetostrictive iron oxides, etc. that have undergone a controllable heat treatment process and have undergone changes in surface topology and chemical structure. The piezoelectric thin layer can be, but is not limited to, lead magnesium niobate-lead titanate piezoelectric single crystals or lead zirconate titanate piezoelectric ceramics with high electromechanical coupling coefficients. When preparing the magnetic field sensor probe, by setting the lengths of the two axes of the acoustic wave excited magnetoelectric antenna, the X and Y axis directions of the acoustic wave excited magnetoelectric antenna have different mechanical resonant frequencies to avoid antenna excitation frequency crosstalk. The acoustic wave excitation antenna is applied to a three-axis Hall sensor to form a composite three-axis Hall sensor. The frequency band of a low-frequency signal to be measured is transferred to a higher frequency band through the acoustic wave excitation antenna, and the magnetic field signal to be measured in the output signal of the Hall probe passing through the three-axis Hall sensor is restored through a demodulation circuit. The noise power spectral density of the Hall probe in the higher frequency band is lower, and the sensor noise is reduced through frequency transfer.

[0030] like Figure 1 As shown, the composite three-axis Hall sensor based on the acoustic wave excitation antenna of the present invention includes a Hall probe 8, an acoustic wave excitation magnetoelectric antenna 5 and a substrate 6. The Hall probe 8 includes a Hall probe HPa 1, a Hall probe HPb 2, a Hall probe HPc 3 and a Hall probe HPd 4. The Hall probes HPa 1, HPc 2, HPb 3 and HPd 4 are prepared on the substrate 6 by micro-nano processing and etching technology. The acoustic wave excitation magnetoelectric antenna 5 is in the shape of a cross with two axes of unequal lengths, the center part of which is fixed on the substrate 6, and the ends of the two axes are respectively located on the Hall probes HPa 1, HPb 2, HPc 3 and HPd 4. The structure of each Hall probe is as follows: Figure 3 As shown, it includes a first electrode 20 and a second electrode 21 for input current, and a third electrode 22 and a fourth electrode 23 for test voltage. The four electrodes are connected to the upper, lower, left and right ends of the Hall probe 8. The direction perpendicular to the plane of the substrate 6 is defined as the Z-axis direction. The magnetic field strength in the Z-axis direction can be obtained from the common-mode components of the Hall probe HPa 1, the Hall probe HPb 2, the Hall probe HPc 3, and the Hall probe HPd 4. The direction along the long axis of the acoustic wave excited magnetoelectric antenna 5 is defined as the X-axis. According to the principle of symmetry, the magnetic field strength in the X-axis direction can be obtained from the differential-mode components after demodulation of the Hall probes HPa 1 and HPb 2. The direction parallel to the short axis of the acoustic wave excited magnetoelectric antenna 5 is defined as the Y-axis direction. The magnetic field strength in the Y-axis direction can be obtained from the differential-mode components after demodulation of the Hall probes HPc 3 and HPd 4. The actual magnetic field strength B in three directions x,B y ,B z and the output voltage V of the four Hall probes HPa ,V HPa ,V HPa ,V HPa The relationship between can be defined by formula (1), where f(.) is the signal conversion coefficient of the four sets of Hall probes, and g(.) is the signal conversion coefficient of the four sets of antenna-Hall probe composite structures.

[0031]

[0032] From (1), the three-axis magnetic field strength can be obtained as:

[0033]

[0034] Since the noise power spectral density of the Hall probe decreases with increasing frequency, the noise of the X and Y axes of the composite sensor plane based on the antenna-probe mode belongs to the high frequency band of the antenna carrier, so the noise is relatively low.

[0035] like Figure 2 As shown, the signal amplification and demodulation circuit of the Hall probe of the present invention includes an antenna excitation signal source 12, a signal amplification module, a signal demodulation module and a feedback module. The antenna signal excitation source 12 is composed of an oscillator with high frequency stability and low noise, and components such as capacitors and resistors. The signal amplification module 9 includes a low-noise voltage operational amplifier circuit and components such as capacitors and resistors. The signal demodulation module includes a multiplier 10 and a low-pass filter 11. Under the action of the antenna signal excitation source 12, the long axis or short axis of the acoustic wave excited magnetoelectric antenna 5 is controlled by the reverse magnetoelectric coupling effect. Figure 4 The first, second, and third magnetostrictive materials 24, 25, and 26 emit excitation magnetic field carrier signals, and at the same time, the low-frequency magnetic field signal to be measured modulates the carrier signal in the two axes of the acoustic wave excitation magnetoelectric antenna 5, and the modulated magnetic field signal acts on the Hall probe 8. The bias voltage source 13 is the voltage end of the Hall probe 8, and the first ground pole 16 and the second ground pole 17 are grounded. The output of the Hall probe 8 is connected to the signal amplification module 9, and its output is connected to the antenna input end through the voltage negative feedback circuit 14. At the same time, the output is connected to the multiplier 10 to realize the demodulation of the low-frequency signal. The output end of the multiplier 10 is connected to the low-pass filter 11 to realize the filtering function of the high-order harmonics, and the voltage signal is output at the output end 18. The output signal realizes voltage negative feedback through the feedback resistor 15.

[0036] Preferably, the Hall probe may also be other types of planar magnetic field sensors, such as an anomalous Hall effect magnetic field sensor.

[0037] Preferably, the antenna signal excitation source 12 is an oscillator alternating voltage source.

[0038] The magnetic material used in the antenna of the present invention can be other ferromagnetic materials with high magnetostriction coefficient and high magnetic flux coefficient, such as iron-based amorphous, iron-cobalt-silicon-boron film, nickel-zinc-iron oxide film and other materials; the piezoelectric material can use piezoelectric materials with high electromechanical coupling coefficient and low energy loss coefficient, such as aluminum nitride piezoelectric film, lead zirconate titanate piezoelectric film or lead magnesium niobate-lead titanate piezoelectric single crystal film and other materials.

[0039] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite three-axis Hall sensor based on acoustic wave excited magnetic antenna, characterized in that: It comprises a Hall probe and an acoustic wave excited magnetoelectric antenna; the acoustic wave excited magnetoelectric antenna is applied to a three-axis Hall sensor to form a composite three-axis Hall sensor, the frequency band of a low-frequency signal to be measured is transferred to a higher frequency band by the acoustic wave excited magnetoelectric antenna, and the magnetic field signal to be measured in the output signal of the Hall probe of the three-axis Hall sensor is restored by a demodulation circuit; the noise power spectrum density of the Hall probe in the higher frequency band is lower, and the sensor noise is reduced by frequency transfer; The Hall probes include Hall probe HPa, Hall probe HPb, Hall probe HPc and Hall probe HPd; the Hall probes HPa, Hall probe HPb, Hall probe HPc and Hall probe HPd are prepared on a substrate by micro-nano processing and etching; the acoustic wave excited magnetoelectric antenna is in a cross shape with two axes of unequal lengths, the center part is fixed on the substrate, and the ends of the two axes are respectively located at the Hall probes HPa, Hall probes HPb and Hall probes HPc and Hall probe HPd; the direction perpendicular to the plane of the substrate is defined as the Z-axis direction, and the magnetic field strength in the Z-axis direction is obtained by the common-mode components of Hall probes HPa, HPb, HPc, and HPd; the direction along the long axis of the acoustic wave excited magnetoelectric antenna is defined as the X-axis, and according to the principle of symmetry, the magnetic field strength in the X-axis direction is obtained by the differential-mode components after demodulation of Hall probes HPa and HPb; the direction parallel to the short axis of the acoustic wave excited magnetoelectric antenna is defined as the Y-axis direction, and the magnetic field strength in the Y-axis direction is obtained by the differential-mode components after demodulation of Hall probes HPc and HPd; the actual magnetic field strength B in the X, Y, and Z-axis directions x , B y , B z And the output voltage V of Hall probe HPa, Hall probe HPb, Hall probe HPc, and Hall probe HPd HPa , V HPb ,V HPc , V HPd The relationship between is defined by formula (1): （1） Among them, f(.) is the signal conversion coefficient of the four sets of Hall probes, and g(.) is the signal conversion coefficient of the four sets of antenna-Hall probe composite structures; The magnetic field strengths on the X, Y, and Z axes are obtained from formula (1): （2）。 2. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 1, characterized in that: The signal amplification and demodulation circuit of the Hall probe includes an antenna excitation signal source, a signal amplification module, a signal demodulation module and a feedback module; the antenna excitation signal source is composed of an oscillator with high frequency stability and low noise, a capacitor and a resistor, the signal amplification module includes a low-noise voltage operational amplifier circuit, a capacitor and a resistor, and the signal demodulation module includes a multiplier and a low-pass filter.

3. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 1, characterized in that: Under the action of the alternating voltage of the oscillator, the acoustic wave excited magnetoelectric antenna emits an excitation magnetic field carrier signal from the magnetostrictive phase material in the acoustic wave excited magnetoelectric antenna through the inverse magnetoelectric coupling effect, and at the same time, the low-frequency magnetic field signal to be measured modulates the carrier signal in the acoustic wave excited magnetoelectric antenna, and the modulated magnetic field signal acts on the Hall probe, and the bias voltage source is the power supply of the Hall probe; the output of the Hall probe is connected to the signal amplification module, and the output of the signal amplification module is fed back to the antenna input end through voltage negative feedback, and at the same time, the output is connected to a multiplier, and the multiplier realizes demodulation of the low-frequency signal, and the output end of the multiplier is connected to a low-pass filter, and the low-pass filter realizes the filtering function of high-order harmonics, and outputs a voltage signal at the output end, and the output signal realizes voltage negative feedback through a feedback resistor.

4. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 1, characterized in that: The Hall probe is a semiconductor film made of indium antimonide or indium gallium arsenide.

5. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 1, characterized in that: The acoustic wave excited magnetoelectric antenna is composed of a layer of ferromagnetic material with high magnetostriction and high magnetic permeability and a layer of piezoelectric thin layer.

6. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 5, characterized in that: The ferromagnetic material is an iron-based amorphous material, an iron-based nanocrystalline magnetostrictive material or a magnetostrictive iron oxide that has undergone a controllable heat treatment process and has undergone changes in surface topology and chemical structure.

7. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 5, characterized in that: The piezoelectric thin layer is a lead magnesium niobate-lead titanate piezoelectric single crystal or a lead zirconate titanate piezoelectric ceramic with a high electromechanical coupling coefficient.

8. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 1, characterized in that: By setting the lengths of the acoustic wave excited magnetoelectric antennas in two directions, the two acoustic wave excited magnetoelectric antennas have different mechanical resonance frequencies, thereby avoiding crosstalk of antenna excitation frequencies.

9. The composite three-axis Hall sensor based on acoustic wave excited magnetic antenna according to claim 1, characterized in that: The Hall probe is a planar magnetic field sensor.

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