Hall sensor with frequency output

Abstract

The present invention provides a Hall sensor with frequency output, belonging to the technical field of sensors. The Hall sensor includes: a compensation circuit for providing a reference voltage independent of an externally applied magnetic field; the variation law of the reference voltage with temperature is the same as that of the measurement circuit; a measurement circuit for generating a Hall voltage according to the externally applied magnetic field; and further for measuring the frequency of the excitation source and determining the magnitude of the externally applied magnetic field according to the frequency of the excitation source; a subtractor for calculating the voltage difference between the reference voltage and the Hall voltage and feeding back the voltage difference to the excitation source; a measurement circuit excitation source for providing a drive current for the measurement circuit; and for performing negative feedback according to the voltage difference, so that the value of the Hall voltage is always equal to the reference voltage. The present invention utilizes the frequency response characteristic of the Hall voltage to the excitation power supply, converts the Hall voltage into a frequency signal, and obtains the magnetic field intensity value by measuring the frequency signal.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and particularly to a Hall sensor with frequency output. Background Art

[0002] A Hall sensor is a magnetic sensor that can be used to measure magnetic fields. It utilizes the Hall effect in semiconductors to measure magnetic fields by measuring the Hall voltage generated by an external magnetic field in a Hall device.

[0003] In the prior art, the magnitude of the magnetic field is obtained by measuring the Hall voltage of the Hall sensor. However, since the Hall voltage generated by the Hall sensor under the action of the magnetic field is relatively small, an amplifier circuit and a filter circuit are required to amplify and filter the Hall voltage signal. Even so, due to the influence of device noise, the accuracy of the Hall sensor cannot be made very high, greatly limiting the application scenarios of the Hall sensor. Secondly, due to the limitation of the power supply voltage of general chips, the maximum value of the output voltage of the Hall sensor cannot be too large, which requires a compromise between sensitivity and measurement range for the Hall sensor, that is, it is impossible to achieve both high sensitivity and wide measurement range simultaneously. Finally, since the Hall element is greatly affected by temperature, a relatively complex temperature compensation circuit generally needs to be designed. When the temperature changes, the temperature is measured by a temperature sensor, and then the compensation value is calculated according to the temperature change through a certain algorithm to compensate the Hall output voltage of the excitation source, which greatly increases the complexity of the Hall sensor chip. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a Hall sensor with frequency output, which changes the method of directly measuring the Hall voltage in the Hall sensor in the traditional technology to obtain the magnetic field strength. By using the frequency response characteristic of the Hall voltage to the excitation power supply, the Hall voltage is converted into a frequency signal, and the magnetic field strength value is obtained by measuring the frequency signal.

[0005] To achieve the above purpose, the embodiments of the present invention provide a Hall sensor with frequency output, including:

[0006] A compensation circuit for providing a reference voltage independent of the external magnetic field; the variation law of the reference voltage with temperature is the same as that of the Hall voltage output by the measurement circuit; the magnitude of the reference voltage is determined by the frequency of the excitation source and the magnitude of the induction coil current in the compensation circuit;

[0007] A measurement circuit for generating a Hall voltage according to the external magnetic field and making the Hall voltage decrease with the increase of the frequency of the excitation source of the measurement circuit; and for measuring the frequency of the excitation source of the measurement circuit and determining the magnitude of the external magnetic field according to the frequency of the excitation source of the measurement circuit;

[0008] A subtractor for calculating the voltage difference between a reference voltage and a Hall voltage and feeding back the voltage difference to the measurement circuit excitation source;

[0009] A measurement circuit excitation source for providing a drive current to the measurement circuit; and for performing negative feedback according to the voltage difference to adjust the frequency of the measurement circuit excitation source, thereby changing the Hall voltage so that the value of the Hall voltage is always equal to the reference voltage.

[0010] Optionally, the measurement circuit includes: a first Hall element H1, a first capacitor C1, a first differential amplifier, and a first peak extraction circuit;

[0011] The excitation source is connected in parallel to the two drive terminals of the first Hall element H1;

[0012] The first capacitor C1 is connected in parallel between the two Hall electrodes of the first Hall element H1; the two Hall electrodes of the first Hall element H1 are respectively connected to the two input terminals of the first differential amplifier;

[0013] The output terminal of the first differential amplifier is connected to the input terminal of the first peak extraction circuit, and the output terminal of the first peak extraction circuit is connected to the second input terminal of the subtractor.

[0014] Optionally, the compensation circuit includes: a fixed-frequency AC signal source, a second Hall element H2, a second capacitor C2, a first signal processing circuit, a third Hall element H3, a third capacitor C3, a second signal processing circuit, a second differential amplifier, and a second peak extraction circuit;

[0015] A first induction coil is installed on the second Hall element H2; a second induction coil is installed on the third Hall element H3; the currents in the first induction coil and the second induction coil are equal in magnitude and opposite in direction;

[0016] The fixed-frequency AC signal source is connected in parallel to the two drive terminals of the second Hall element H2 and the two drive terminals of the third Hall element H3;

[0017] The second capacitor C2 is connected in parallel between the two Hall electrodes of the second Hall element H2; the two Hall electrodes of the second Hall element H2 are connected to the input terminal of the first signal processing circuit, and the output terminal of the first signal processing circuit is connected to the first input terminal of the second differential amplifier;

[0018] The third capacitor C3 is connected in parallel between the two Hall electrodes of the third Hall element H3; the two Hall electrodes of the third Hall element H3 are connected to the input terminal of the second signal processing circuit, and the output terminal of the second signal processing circuit is connected to the second input terminal of the second differential amplifier;

[0019] The output terminal of the second differential amplifier is connected to the input terminal of the second peak extraction circuit, and the output terminal of the second peak extraction circuit is connected to the first input terminal of the subtractor.

[0020] Optionally, the measurement circuit excitation source is a tunable frequency AC excitation source.

[0021] Optionally, the amplitude of the tunable frequency AC excitation source is the same as the amplitude of the fixed frequency AC signal source.

[0022] Optionally, the first Hall element H1, the second Hall element H2, and the third Hall element H3 are Hall elements with the same material, shape, and size.

[0023] Optionally, the capacitances of the first capacitor C1, the second capacitor C2, and the third capacitor C3 are the same.

[0024] Optionally, the expression for the amplitude of the reference voltage provided by the compensation circuit is:

[0025]

[0026] In the formula, V R is the amplitude of the reference voltage; μ is the carrier mobility; W is the width of the Hall element; L is the length of the Hall element; V is the amplitude of the excitation signal; B con is the magnetic field generated by the induction coil; R is the output resistance of the Hall element, C is the capacitance between the electrodes of the Hall element; f R is the frequency of the fixed frequency AC signal source.

[0027] Optionally, the expression for the amplitude of the Hall voltage generated by the measurement circuit is:

[0028]

[0029] In the formula, V H is the amplitude of the Hall voltage generated by the measurement circuit; μ is the carrier mobility; W is the width of the Hall element; L is the length of the Hall element; V is the amplitude of the excitation signal; B is the externally applied magnetic field; R is the output resistance of the Hall element, C is the capacitance between the electrodes of the Hall element; f is the frequency of the voltage-controlled variable frequency AC signal source.

[0030] Optionally, determining the magnitude of the externally applied magnetic field according to the frequency of the excitation source should satisfy the following formula:

[0031]

[0032] When RCf and RCf R are much greater than 1, equation (6) can be simplified to:

[0033]

[0034] In the formula, B is the externally applied magnetic field; B con is the magnetic field generated by the induction coil; f is the frequency of the voltage-controlled variable-frequency AC signal source; f R is the frequency of the fixed-frequency AC signal source.

[0035] Compared with the prior art, the above technical solution of the present invention has the following beneficial effects:

[0036] This application provides a Hall sensor that uses frequency output. By utilizing the frequency response characteristic of the Hall voltage to the excitation power supply, the Hall voltage is converted into a frequency signal. The magnetic field intensity value is obtained by measuring the frequency signal. The measurement range is not affected by the upper limit of the power supply voltage, and the sensitivity of magnetic field measurement can be improved while ensuring the maximum measurement range.

[0037] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0039] Figure 1 Schematically shows the principle structure diagram of the Hall sensor with frequency output according to the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiments of the present application, and is not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present application.

[0041] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present application, such descriptions of "first", "second", etc. are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0042] In the prior art, the Hall sensor works by applying a voltage or current excitation to the Hall sensor to make the carriers in the Hall device flow in a certain direction. When a magnetic field perpendicular to the surface of the Hall device is applied again, the carriers flowing in a certain direction are deflected under the action of the Lorentz force. When the equilibrium state is reached, a pressure difference proportional to the magnetic field strength will be generated between the two sides of the Hall element, which becomes the Hall voltage. By measuring this Hall voltage, the value of the magnetic field strength can be obtained. Currently, in the prior art, the Hall voltage is directly measured to calculate the value of the externally applied magnetic field. Since the Hall voltage is generally relatively small, the voltage needs to be amplified, filtered, and compensated for offset and temperature drift. However, in essence, it is a direct measurement of the Hall voltage. Whether it is digital output or analog output, the output is a voltage signal.

[0043] The present invention changes the method of directly measuring the Hall voltage in the Hall sensor in the traditional technology to obtain the magnetic field strength. By using the frequency response characteristic of the Hall voltage to the excitation power supply, the Hall voltage is converted into a frequency signal, and the magnetic field strength value is obtained by measuring the frequency signal.

[0044] This embodiment includes a Hall device, and the Hall device can be any form of Hall device. It includes an excitation source that can adjust the frequency. The excitation source can be a sine wave, a square wave or other waveforms, and can be a voltage source or a current source. It also includes a capacitor that is connected between the two Hall electrodes of the Hall device. First, when the magnetic field is certain, under the action of the excitation source, the Hall output voltage is also a voltage signal with the same frequency as the excitation source. Due to the charge and discharge effect of the capacitor, the maximum value of the output Hall voltage changes with the frequency. The specific relationship is determined by the following formula:

[0045]

[0046] where, V H0 is the Hall voltage output at zero frequency; V Hf is the maximum value of the Hall voltage at frequency f (i.e., the amplitude of the Hall output voltage); R is the output resistance of the Hall device, C is the capacitance between the Hall electrodes of the Hall device; the expression of V H0 is as follows (powered by a constant voltage source):

[0047]

[0048] where, μ is the carrier mobility; W is the width of the Hall element; L is the length of the Hall element; V is the amplitude of the excitation signal; B is the externally applied magnetic field.

[0049] As can be seen from Formulas (1) to (2), when the externally applied magnetic field B and the amplitude V of the excitation signal remain unchanged, increasing the frequency f will result in a decrease in the amplitude of the Hall output voltage. From another perspective, if we fix the amplitude of the Hall output voltage at a value independent of the externally applied magnetic field by adjusting the frequency of the excitation signal, then the frequency of the excitation source is directly proportional to the externally applied magnetic field. The specific relationship is as follows:

[0050]

[0051] where μ is the carrier mobility; W is the width of the Hall element; V is the amplitude of the excitation signal; L is the length of the Hall element; V Hcon is the voltage value independent of the external magnetic field; R is the output resistance of the Hall device; C is the capacitance between the Hall electrodes of the Hall device; and B is the externally applied magnetic field. Then, by collecting the frequency of the excitation signal, the intensity of the externally applied magnetic field can be obtained.

[0052] As can be seen from the above formula, not only can the magnetic field value be obtained by measuring the frequency, but the measurement sensitivity can also be changed by adjusting various parameters. Among them, it is most convenient to change the capacitance value C and the R value. Since the frequency signal is collected, the output maximum value is not limited by the power supply voltage. Therefore, the measurement range of the Hall sensor can be greatly expanded. At the same time, by appropriately adjusting the values of R and C, relatively high sensitivity can also be obtained.

[0053] Regarding the temperature compensation method, the parameters most significantly affected by temperature in the above formula are the carrier mobility μ and the output resistance R value of the Hall device. Because in this invention, the maximum value of the output Hall voltage and V Hcon are directly compared, and the frequency value of the excitation power supply is changed according to the difference. Therefore, the influence of temperature on the Hall voltage can be directly compensated by making V Hcon change with temperature.

[0054] Figure 1 Schematically shows the principle structure diagram of a Hall sensor with frequency output according to an embodiment of the present application. As Figure 1 shown, in an embodiment of the present application, a Hall sensor with frequency output is provided, including:

[0055] A compensation circuit for providing a reference voltage independent of the externally applied magnetic field; the variation law of the reference voltage with temperature is the same as that of the Hall voltage output by the measurement circuit; the magnitude of the reference voltage is determined by the frequency of the excitation source and the magnitude of the induction coil current in the compensation circuit.

[0056] Specifically, as Figure 1As shown, the compensation circuit includes: a fixed-frequency AC signal source, a second Hall element H2, a second capacitor C2, a first signal processing circuit, a third Hall element H3, a third capacitor C3, a second signal processing circuit, a second differential amplifier, and a second peak extraction circuit; a first induction coil is mounted on the second Hall element H2; a second induction coil is mounted on the third Hall element H3; the currents in the first induction coil and the second induction coil are equal in magnitude and opposite in direction; the fixed-frequency AC signal source is connected in parallel to the two drive ends of the second Hall element H2 and the two drive ends of the third Hall element H3; the second capacitor C2 is connected in parallel between the two Hall electrodes of the second Hall element H2; the two Hall electrodes of the second Hall element H2 are connected to the input end of the first signal processing circuit, and the output end of the first signal processing circuit is connected to the first input end of the second differential amplifier; the third capacitor C3 is connected in parallel between the two Hall electrodes of the third Hall element H3; the two Hall electrodes of the third Hall element H3 are connected to the input end of the second signal processing circuit, and the output end of the second signal processing circuit is connected to the second input end of the second differential amplifier; the output end of the second differential amplifier is connected to the input end of the second peak extraction circuit, and the output end of the second peak extraction circuit is connected to the first input end of the subtractor. The fixed-frequency AC signal source is the excitation source in the compensation circuit.

[0057] Specifically, the compensation circuit is responsible for generating a reference voltage independent of the externally applied magnetic field, and the amplitude expression of this reference voltage is:

[0058]

[0059] In the formula, V R is the amplitude of the reference voltage; μ is the carrier mobility; W is the width of the Hall element; L is the length of the Hall element; V is the amplitude of the excitation signal, that is, the amplitude of the fixed-frequency AC signal source in the compensation circuit; B con is the magnetic field generated by the induction coil; R is the output resistance of the Hall element, and C is the capacitance between the Hall element electrodes; f R is the frequency of the fixed-frequency AC signal source.

[0060] A measurement circuit, which is used to generate a Hall voltage according to the externally applied magnetic field and make the Hall voltage decrease as the frequency of the measurement circuit excitation source increases; and is used to measure the frequency of the measurement circuit excitation source and determine the magnitude of the externally applied magnetic field according to the frequency of the measurement circuit excitation source.

[0061] Specifically, as Figure 1As shown, the measurement circuit includes: a first Hall element H1, a first capacitor C1, a first differential amplifier, and a first peak extraction circuit; the excitation source is connected in parallel to the two drive terminals of the first Hall element H1; the first capacitor C1 is connected in parallel between the two Hall electrodes of the first Hall element H1; the two Hall electrodes of the first Hall element H1 are respectively connected to the two input terminals of the first differential amplifier; the output terminal of the first differential amplifier is connected to the input terminal of the first peak extraction circuit, and the output terminal of the first peak extraction circuit is connected to the second input terminal of the subtractor.

[0062] Specifically, the excitation source of the measurement circuit is a frequency-adjustable AC excitation source. In this embodiment, a voltage-controlled variable-frequency AC signal source is used as the excitation source of the measurement circuit.

[0063] Specifically, the expression of the Hall voltage generated by the measurement circuit is as follows:

[0064]

[0065] In the formula, V H is the amplitude of the Hall voltage generated by the measurement circuit; μ is the carrier mobility; W is the width of the Hall element; L is the length of the Hall element; V is the amplitude of the excitation signal, that is, the amplitude of the frequency-adjustable AC excitation source in the measurement circuit; B is the externally applied magnetic field; R is the output resistance of the Hall element, C is the capacitance between the electrodes of the Hall element; f is the frequency of the voltage-controlled variable-frequency AC signal source.

[0066] In this embodiment, the amplitude of the fixed-frequency AC signal source in the compensation circuit is the same as the amplitude of the frequency-adjustable AC excitation source in the measurement circuit.

[0067] Specifically, the first Hall element H1, the second Hall element H2, and the third Hall element H3 are Hall elements with the same material, shape, and size; the capacitances of the first capacitor C1, the second capacitor C2, and the third capacitor C3 are the same.

[0068] The subtractor is used to calculate the voltage difference between the reference voltage and the Hall voltage, and feedback the voltage difference to the excitation source of the measurement circuit.

[0069] The excitation source of the measurement circuit is used to provide a driving current for the measurement circuit; and is used for negative feedback according to the voltage difference to adjust the frequency of the excitation source of the measurement circuit, so as to change the Hall voltage, so that the value of the Hall voltage is always equal to the reference voltage.

[0070] Specifically, the excitation source of the measurement circuit is an excitation source that can be frequency-adjusted. The excitation source can be a sine wave, a square wave, or other waveforms, and can be a voltage source or a current source. The excitation source in this embodiment is a voltage-controlled variable-frequency AC signal source.

[0071] Specifically, make V H and VR Subtract and then feedback to the voltage-controlled variable-frequency AC signal source. By using negative feedback, make V H and V R always equal. In this way, a simple relationship between f and the externally applied magnetic field B can be obtained as follows:

[0072]

[0073] When RCf and RCf R is much greater than 1, Equation (6) can be simplified to:

[0074]

[0075] In the formula, B is the externally applied magnetic field; B con is the magnetic field generated by the induction coil; f is the frequency of the voltage-controlled variable-frequency AC signal source; f R is the frequency of the fixed-frequency AC signal source.

[0076] In this embodiment, an adjustable-frequency AC excitation source is used to provide excitation to the Hall sensor. By using the RC circuit formed by the capacitance between the two Hall electrodes of the Hall element (which can be an externally added capacitance or a parasitic capacitance caused by the capacitance effect of the Hall element itself) and the output resistance of the Hall element, the amplitude of the Hall output voltage changes with the change of frequency. Compare the amplitude of the Hall output voltage that changes with frequency with a reference voltage independent of the externally applied magnetic field to generate a negative feedback. This feedback quantity adjusts the frequency of the adjustable-frequency AC excitation source, and the adjustment result makes the amplitude of the Hall voltage always equal to the reference voltage. Under the condition of ensuring that the Hall voltage and the reference voltage are always equal, measure the frequency of the excitation source. This frequency has a linear relationship with the external magnetic field. Therefore, the external magnetic field strength value can be obtained by measuring the frequency. The temperature compensation circuit generates an output voltage independent of the external magnetic field as the reference voltage by the differential output of two Hall sensors with induction coils. The excitation source of the temperature compensation circuit is selected as an AC excitation source with a certain frequency. In this way, the reference voltage expression contains two quantities, the Hall output resistance R and the capacitance C between the Hall electrodes. By comparing with the Hall output voltage in the measurement circuit, the temperature drift of the sensor caused by the change of R and C with temperature can be eliminated.

[0077] In this embodiment, the magnetic field is measured by measuring the frequency. The frequency change range is large, and the measurement range is not affected by the upper limit of the power supply voltage.

[0078] In this embodiment, measuring the magnetic field by measuring the frequency can obtain relatively high sensitivity, and the sensitivity is not affected on the premise of ensuring the maximum measurement range. Moreover, the sensitivity can be optimized by adjusting multiple parameters, which improves the design freedom of the device.

[0079] This embodiment measures the magnetic field by measuring the frequency. The frequency output is more convenient for digitization and does not require A / D conversion, reducing the complexity and cost of the circuit. This method is naturally compatible with the rotating current method and can effectively eliminate the influence of the Hall offset voltage.

[0080] This embodiment adjusts the frequency to compare the measured Hall voltage with the reference voltage and performs negative feedback. By selecting an appropriate reference voltage, temperature compensation can be automatically achieved, greatly simplifying the design of the temperature compensation circuit and reducing the temperature drift of the sensor.

[0081] This embodiment uses a high-frequency excitation source to provide excitation for the Hall sensor, which can effectively eliminate 1 / f noise and improve the accuracy of the Hall sensor.

[0082] The above scheme is only one implementation scheme of the present invention. The form of the compensation circuit can also select other feasible schemes, not limited to this one scheme.

[0083] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or device including the element.

[0084] The above are only embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A Hall sensor with frequency output, characterized in that: include: A compensation circuit for providing a reference voltage that is independent of an external magnetic field; The variation of the reference voltage with temperature is the same as the variation of the Hall voltage output by the measurement circuit with temperature; the magnitude of the reference voltage is determined by the frequency of the excitation source in the compensation circuit and the magnitude of the induction coil current; a measuring circuit for generating a Hall voltage in response to an externally applied magnetic field, and utilizing an RC circuit formed by a capacitance between two Hall electrodes of a Hall element and an output resistance of the Hall element to cause the Hall voltage to decrease as the frequency of an excitation source of the measuring circuit increases; and a measuring circuit for measuring the frequency of the excitation source of the measuring circuit and determining the magnitude of the externally applied magnetic field based on the frequency of the excitation source of the measuring circuit; a subtractor, configured to calculate a voltage difference between a reference voltage and a Hall voltage, and feed the voltage difference back to a measurement circuit excitation source; A measurement circuit excitation source, used for providing a driving current for the measurement circuit; And it is used to perform negative feedback according to the voltage difference to adjust the frequency of the measurement circuit excitation source, thereby changing the Hall voltage so that the value of the Hall voltage is always equal to the reference voltage.

2. The Hall sensor with frequency output according to claim 1, characterized in that: The measurement circuit includes: a first Hall element H1, a first capacitor C1, a first differential amplifier and a first peak extraction circuit; The excitation source is connected in parallel to the two driving ends of the first Hall element H1; The first capacitor C1 is connected in parallel between the two Hall electrodes of the first Hall element H1; the two Hall electrodes of the first Hall element H1 are respectively connected to the two input terminals of the first differential amplifier; The output terminal of the first differential amplifier is connected to the input terminal of the first peak extraction circuit, and the output terminal of the first peak extraction circuit is connected to the second input terminal of the subtractor.

3. The Hall sensor with frequency output according to claim 2, characterized in that: The compensation circuit includes: a fixed-frequency AC signal source, a second Hall element H2, a second capacitor C2, a first signal processing circuit, a third Hall element H3, a third capacitor C3, a second signal processing circuit, a second differential amplifier and a second peak extraction circuit; A first induction coil is mounted on the second Hall element H2; a second induction coil is mounted on the third Hall element H3; currents in the first induction coil and the second induction coil are equal in magnitude and opposite in direction; The fixed-frequency AC signal source is connected in parallel to the two driving ends of the second Hall element H2 and the two driving ends of the third Hall element H3; The second capacitor C2 is connected in parallel between the two Hall electrodes of the second Hall element H2; the two Hall electrodes of the second Hall element H2 are connected to the input end of the first signal processing circuit, and the output end of the first signal processing circuit is connected to the first input end of the second differential amplifier; The third capacitor C3 is connected in parallel between the two Hall electrodes of the third Hall element H3; the two Hall electrodes of the third Hall element H3 are connected to the input end of the second signal processing circuit, and the output end of the second signal processing circuit is connected to the second input end of the second differential amplifier; The output terminal of the second differential amplifier is connected to the input terminal of the second peak extraction circuit, and the output terminal of the second peak extraction circuit is connected to the first input terminal of the subtractor.

4. The Hall sensor with frequency output according to claim 3, characterized in that: The measuring circuit excitation source is a frequency-adjustable AC excitation source.

5. The Hall sensor with frequency output according to claim 4, characterized in that: The amplitude of the adjustable frequency AC excitation source is the same as the amplitude of the fixed frequency AC signal source.

6. The Hall sensor with frequency output according to claim 3, characterized in that: The first Hall element H1 , the second Hall element H2 and the third Hall element H3 are Hall elements with the same material, shape and size.

7. The Hall sensor with frequency output according to claim 6, characterized in that: The first capacitor C1 , the second capacitor C2 , and the third capacitor C3 have the same capacitance.

8. The Hall sensor with frequency output according to claim 7, characterized in that: The expression of the reference voltage amplitude provided by the compensation circuit is: （4）； Where, is the reference voltage amplitude; is the carrier mobility; is the width of the Hall element; is the length of the Hall element; is the excitation signal amplitude; is the magnetic field generated by the induction coil; is the output resistance of the Hall element, is the capacitance between the electrodes of the Hall element; is the frequency of the fixed-frequency AC signal source.

9. The Hall sensor with frequency output according to claim 8, characterized in that: The Hall voltage amplitude expression generated by the measurement circuit is: （5）； Where, is the Hall voltage amplitude generated by the measurement circuit; is the carrier mobility; is the width of the Hall element; is the length of the Hall element; is the excitation signal amplitude; is the external magnetic field; is the output resistance of the Hall element, is the capacitance between the electrodes of the Hall element; is the frequency of the voltage-controlled variable frequency AC signal source.

10. The Hall sensor with frequency output according to claim 9, characterized in that: The magnitude of the external magnetic field is determined according to the frequency of the excitation source and should satisfy the following formula: （6）； when and When is much larger than 1, equation (6) can be simplified to: （7）； Where, is the external magnetic field; is the magnetic field generated by the induction coil; is the frequency of the voltage-controlled variable frequency AC signal source; is the frequency of the fixed-frequency AC signal source.

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