Magnetic field intensity detection circuit, control method of magnetic field intensity detection circuit and magnetic field intensity detection equipment

Abstract

The invention relates to a magnetic field intensity detection circuit, a control method of the magnetic field intensity detection circuit and magnetic field intensity detection equipment, and the magnetic field intensity detection circuit comprises a gain resonance unit which comprises a first inductance coil, a first capacitor and a nonlinear negative resistor; the first inductance coil, the first capacitor and the nonlinear negative resistor are connected in parallel; the loss resonance unit comprises a second inductance coil, a second capacitor and a positive resistor; the second inductance coil, the second capacitor and the positive resistor are connected in parallel; wherein the first inductance coil and the second inductance coil are coaxially arranged; the magnetic field intensity detection circuit determines the magnetic field intensity of the to-be-detected magnetic field based on the voltage signal of the gain resonance unit. The magnetic field intensity detection circuit can improve the sensitivity of magnetic field intensity detection.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic field strength detection, and particularly to a magnetic field strength detection circuit, a control method for the magnetic field strength detection circuit, and a magnetic field strength detection device. Background Art

[0002] Magnetic field strength detection technology is widely used in fields such as industrial non-destructive testing, biomedical imaging, and environmental monitoring. Traditional magnetic field sensors mainly rely on principles such as the Hall effect, magnetoresistive effect, or superconducting quantum interference devices. Although they have certain sensitivity, they are limited by problems such as narrow linear response range, large noise interference, or high device complexity. For example, the signal-to-noise ratio of Hall sensors decreases significantly under weak magnetic fields, while superconducting quantum interference devices require a cryogenic environment, are costly, and are difficult to miniaturize.

[0003] In recent years, wireless passive sensors based on the inductance-capacitance (LC) resonance principle have become a research hotspot due to their advantages such as simple structure and no external power supply. However, their sensitivity is limited by the coupling efficiency and frequency detection accuracy, and it is difficult to meet the requirements of high-precision magnetic field detection. Therefore, how to improve the sensitivity of magnetic field strength detection is a problem that needs to be solved. Summary of the Invention

[0004] Based on this, it is necessary to provide a magnetic field strength detection circuit, a control method for the magnetic field strength detection circuit, and a magnetic field strength detection device to improve the sensitivity of magnetic field strength detection.

[0005] In the first aspect of the present application, a magnetic field strength detection circuit is provided, including:

[0006] A gain resonance unit, including a first inductance coil, a first capacitor, and a non-linear negative resistor; the first inductance coil, the first capacitor, and the non-linear negative resistor are connected in parallel with each other;

[0007] A loss resonance unit, including a second inductance coil, a second capacitor, and a positive resistor; the second inductance coil, the second capacitor, and the positive resistor are connected in parallel with each other;

[0008] Wherein, the first inductance coil and the second inductance coil are coaxially placed;

[0009] The magnetic field strength detection circuit determines the magnetic field strength of the magnetic field to be measured based on the voltage signal of the gain resonance unit.

[0010] In one embodiment, when the magnetic field strength detection circuit is in the initial state, the absolute value of the resistance of the non-linear negative resistor is less than the central resistance value of the positive resistor; wherein, the resistance value of the positive resistor changes periodically.

[0011] In one embodiment, when the magnetic field strength detection circuit is in the initial state, the modulation frequency of the positive resistor is the same as the resonant frequency of the magnetic field strength detection circuit; wherein, the resistance value of the positive resistor changes periodically.

[0012] In one embodiment, when the magnetic field strength detection circuit is in the initial state, the coupling distance between the first inductance coil and the second inductance coil is less than twice the diameter of the inductance coil corresponding to the first inductance coil and / or the second inductance coil.

[0013] In one embodiment, the non-linear negative resistor includes a positive feedback resistor, a negative feedback resistor, a voltage dividing resistor, and an operational amplifier; wherein,

[0014] One end of the positive feedback resistor is connected to the non-inverting input terminal of the operational amplifier, one end of the first inductance coil, and one end of the first capacitor; the other end of the positive feedback resistor is connected to the output terminal of the operational amplifier;

[0015] One end of the negative feedback resistor is connected to the inverting input terminal of the operational amplifier, and the other end of the negative feedback resistor is connected to the output terminal of the operational amplifier;

[0016] One end of the voltage dividing resistor is connected to the inverting input terminal of the operational amplifier; the other end of the voltage dividing resistor is connected to the other end of the first inductance coil and the other end of the first capacitor.

[0017] In one embodiment, the inductance value of the first inductance coil is equal to the inductance value of the second inductance coil.

[0018] In one embodiment, the capacitance value of the first capacitor is equal to the capacitance value of the second capacitor.

[0019] In one embodiment, one end of the first capacitor is grounded, and one end of the second capacitor is grounded.

[0020] In the second aspect of the present application, a control method for a magnetic field strength detection circuit is provided, which is applied to the magnetic field strength detection circuit as described in the first aspect. The method includes:

[0021] Adjust the resistance value of the non-linear negative resistor so that the absolute value of the resistance of the non-linear negative resistor is less than the central resistance value of the positive resistor;

[0022] Adjust the coupling distance between the first inductance coil and the second inductance coil so that the coupling distance is less than twice the diameter of the inductance coil corresponding to the first inductance coil and / or the second inductance coil;

[0023] Obtain the resonant frequency of the magnetic field strength detection circuit, and adjust the modulation frequency of the positive resistor to be the same as the resonant frequency of the magnetic field strength detection circuit; wherein, the resistance value of the positive resistor changes periodically around the central resistance value;

[0024] When the first inductance coil and the second inductance coil are in the magnetic field to be measured, obtain the voltage signal of the gain resonance unit, and determine the magnetic field strength of the magnetic field to be measured based on the voltage signal.

[0025] In the third aspect of the present application, a magnetic field strength detection device is provided, including the magnetic field strength detection circuit as described in the first aspect.

[0026] Since the above-mentioned magnetic field strength detection circuit includes a gain resonance unit and a loss resonance unit, wherein the gain resonance unit includes a first inductance coil, a first capacitor and a non-linear negative resistor; the first inductance coil, the first capacitor and the non-linear negative resistor are connected in parallel with each other; the loss resonance unit includes a second inductance coil, a second capacitor and a positive resistor; the second inductance coil, the second capacitor and the positive resistor are connected in parallel with each other; the first inductance coil and the second inductance coil are coaxially placed, and the magnetic field strength detection circuit can thus determine the magnetic field strength of the magnetic field to be measured based on the voltage signal of the gain resonance unit. Specifically, in the initial state, the gain resonance unit and the loss resonance unit are in a dynamic time-space symmetric state, and the magnetic field strength to be measured affects the coupling efficiency between the gain resonance unit and the loss resonance unit. When the magnetic field strength to be measured increases, the voltage of the gain resonance unit shows a significant decrease; when the magnetic field strength to be measured decreases, the voltage of the gain resonance unit shows a significant increase. Since the voltage signal of the gain resonance unit can change significantly under the condition of weak change of the magnetic field strength to be measured, the accurate capture of the weak change of the magnetic field strength to be measured is realized, and the sensitivity of the magnetic field strength detection is improved. At the same time, during the process of detecting the magnetic field strength by the magnetic field strength detection circuit, the non-linear negative resistor contained in the gain resonance unit is always in a steady-state oscillation state, thereby reducing the noise of the measured voltage signal and forming a signal output with a high signal-to-noise ratio. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a schematic diagram of the magnetic field strength detection circuit in an embodiment;

[0029] Figure 2 It is a schematic flowchart of the control method of the magnetic field strength detection circuit in an embodiment;

[0030] Figure 3 It is another schematic diagram of the magnetic field strength detection circuit in an embodiment;

[0031] Explanation of the accompanying drawings: 1. Gain resonance unit; 11. First inductor; 12. First capacitor; 13. Nonlinear negative resistor; 131. Positive feedback resistor; 132. Negative feedback resistor; 133. Voltage divider resistor; 134. Operational amplifier; 2. Loss resonance unit; 21. Second inductor; 22. Second capacitor; 23. Periodically changing positive resistor. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0034] It will be understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this application. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0035] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0036] It is understood that “at least one” refers to one or more, “a plurality” refers to two or more, and “at least a portion of an element” refers to a portion or all of an element.

[0037] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0038] Parity-time (PT) symmetry is a physical symmetry that is related to the invariance of physical phenomena. This symmetry indicates that the fundamental physical laws of a physical circuit do not change under spatial mirror operations (parity operations, P operations) and time mirror operations (time-reversal operations, T operations).

[0039] To further improve the sensitivity of magnetic field strength detection, the parity-time symmetry principle is introduced into the sensing field. Its circuit implementation is usually composed of the symmetric coupling of a gain module and a loss module, and PT symmetry is achieved by precisely regulating the gain and loss parameters. When the parameters are adjusted to specific values, the circuit may experience a special state - the exceptional point, at which certain characteristics of the circuit become particularly unique. The PT-symmetric circuit has the property of mode degeneracy at the exceptional point, which enables the circuit near the exceptional point to have a superlinear response characteristic and can significantly improve the sensor sensitivity. However, its application in magnetic field sensing still faces many bottlenecks, such as: the parity-time symmetric circuit depends on the fixed inductor-capacitor-resistor matching and is difficult to adapt to the real-time calibration requirements in a dynamic magnetic field environment; and although the weak coupling condition can suppress some noise, it will sacrifice the signal strength, resulting in a decrease in the signal-to-noise ratio and sensitivity.

[0040] Based on the above analysis, the present application provides a magnetic field strength detection circuit to improve the sensitivity of magnetic field strength detection, which will be described below by way of embodiments.

[0041] In an exemplary embodiment, Figure 1 is a schematic diagram of a magnetic field strength detection circuit in an embodiment, as Figure 1 shown, the magnetic field strength detection circuit includes: a gain resonance unit 1, including a first inductance coil L1 (11), a first capacitor C1 (12), and a nonlinear negative resistor R1 (13); the first inductance coil L1 (11), the first capacitor C1 (12), and the nonlinear negative resistor R1 (13) are connected in parallel with each other; a loss resonance unit 2, including a second inductance coil L2 (21), a second capacitor C2 (22), and a positive resistor R2 (23); the second inductance coil L2 (21), the second capacitor C2 (22), and the positive resistor R2 (23) are connected in parallel with each other.

[0042] Wherein, the first inductance coil L1 (11) and the second inductance coil L2 (21) are coaxially placed; the magnetic field strength detection circuit determines the magnetic field strength of the magnetic field to be measured based on the voltage signal of the gain resonance unit 1.

[0043] In some embodiments, the first capacitor C1 (12) and / or the second capacitor C2 (22) can be a fixed capacitor or a variable capacitor.

[0044] In some embodiments, the voltage of the gain resonance unit 1 can vary according to the magnetic field strength of the magnetic field to be measured.

[0045] In some embodiments, the amplitude of the voltage change of the gain resonance unit 1 can be one time or multiple times the amplitude of the magnetic field strength change of the magnetic field to be measured. Exemplarily, assuming that the amplitude of the magnetic field strength change of the magnetic field to be measured is 10%, the amplitude of the voltage change of the gain resonance unit 1 can be 1000%.

[0046] Since the above magnetic field strength detection circuit includes a gain resonance unit and a loss resonance unit, wherein the gain resonance unit includes a first inductance coil, a first capacitor and a nonlinear negative resistor; the first inductance coil, the first capacitor and the nonlinear negative resistor are connected in parallel with each other; the loss resonance unit includes a second inductance coil, a second capacitor and a positive resistor; the second inductance coil, the second capacitor and the positive resistor are connected in parallel with each other; the first inductance coil and the second inductance coil are coaxially placed, the magnetic field strength detection circuit can thus determine the magnetic field strength of the magnetic field to be measured based on the voltage signal of the gain resonance unit. Specifically, in the initial state, the gain resonance unit and the loss resonance unit are in a dynamic time-space symmetric state, and the magnetic field strength to be measured affects the coupling efficiency between the gain resonance unit and the loss resonance unit. When the magnetic field strength to be measured increases, the voltage of the gain resonance unit shows a significant decrease; when the magnetic field strength to be measured decreases, the voltage of the gain resonance unit shows a significant increase. Since the voltage signal of the gain resonance unit can produce a large change under the condition of a weak change in the magnetic field strength to be measured, the accurate capture of the weak change in the magnetic field strength to be measured is realized, and the sensitivity of the magnetic field strength detection is improved. At the same time, during the process of detecting the magnetic field strength by the magnetic field strength detection circuit, the nonlinear negative resistor contained in the gain resonance unit is always in a steady-state oscillation state, thereby reducing the voltage signal noise of the measurement and forming a signal output with a high signal-to-noise ratio.

[0047] In one embodiment, when the foregoing magnetic field strength detection circuit is in the initial state, the absolute value of the resistance of the foregoing nonlinear negative resistor is less than the central resistance value of the foregoing positive resistor; wherein, the resistance value of the positive resistor changes periodically.

[0048] Among them, the initial state can represent the default state of the magnetic field strength detection circuit at the beginning. Exemplarily, the initial state can be the state where the magnetic field strength detection circuit has not performed magnetic field strength detection.

[0049] In some embodiments, the positive resistor can be a variable resistor. Exemplarily, the positive resistor can change its own resistance value according to a control signal, and the control signal can be determined based on the resonance frequency of the magnetic field strength detection circuit, so as to realize the synchronization of the resistance value change of the positive resistor with the resonance frequency of the magnetic field strength detection circuit.

[0050] In one embodiment, when the magnetic field strength detection circuit is in an initial state, the modulation frequency of the positive resistor is the same as the resonant frequency of the magnetic field strength detection circuit; wherein, the resistance value of the positive resistor changes periodically.

[0051] Wherein, the resonant frequency may be the specific frequency at which the magnetic field strength detection circuit generates the maximum amplitude response or energy transfer at a certain specific frequency, and this specific frequency is the resonant frequency of the magnetic field strength detection circuit.

[0052] In one embodiment, when the magnetic field strength detection circuit is in an initial state, the coupling distance between the first inductance coil and the second inductance coil is less than twice the diameter of the inductance coil corresponding to the first inductance coil and / or the second inductance coil.

[0053] In some embodiments, the distance between the gain resonant unit and the loss resonant unit in the magnetic field strength detection circuit can be variable and non-fixed. Exemplarily, the distance between the first inductance coil and the second inductance coil can be variable and non-fixed.

[0054] In one embodiment, the non-linear negative resistor includes a positive feedback resistor, a negative feedback resistor, a voltage dividing resistor, and an operational amplifier; wherein, one end of the positive feedback resistor is connected to the non-inverting input terminal of the operational amplifier, one end of the first inductance coil, and one end of the first capacitor; the other end of the positive feedback resistor is connected to the output terminal of the operational amplifier; one end of the negative feedback resistor is connected to the inverting input terminal of the operational amplifier, and the other end of the negative feedback resistor is connected to the output terminal of the operational amplifier; one end of the voltage dividing resistor is connected to the inverting input terminal of the operational amplifier; the other end of the voltage dividing resistor is connected to the other end of the first inductance coil and the other end of the first capacitor.

[0055] Wherein, the operational amplifier (Operational Amplifier, abbreviated as Op Amp) can be a circuit unit with a very high amplification factor. Exemplarily, the operational amplifier can perform various mathematical operations on the input voltage, such as addition, subtraction, integration, differentiation, etc.

[0056] In some embodiments, the operational amplifier has two input terminals, namely the non-inverting input terminal (marked as "+") and the inverting input terminal (marked as "-"). Exemplarily, when the voltage of the non-inverting input terminal is higher than that of the inverting input terminal, the output voltage of the operational amplifier is positive; otherwise, the output voltage is negative.

[0057] In some embodiments, the operational amplifier can be a circuit unit with a very high amplification factor, which can be provided with a non-inverting input terminal Vin(+) (also known as the in-phase input terminal), an inverting input terminal Vin(−), and an output terminal Vout. Generally speaking, common operational amplifiers include general-purpose operational amplifiers (such as μA741, LM358, and LM324, etc.), high-impedance operational amplifiers (such as LF355, CA3130, and CA3140, etc.), low-temperature-drift operational amplifiers (such as OP07, OP27, and AD508, etc.), high-speed operational amplifiers (such as LM318, μA715, etc.), low-power operational amplifiers (such as TL-022C, TL-060C, etc.), high-voltage high-power operational amplifiers (such as D41), and programmable control types (such as PGA103A), etc. The operational amplifier adopted in this application can be any of the above types of operational amplifiers, and no specific limitation is made here.

[0058] In one embodiment, the inductance value of the first inductance coil is equal to the inductance value of the second inductance coil.

[0059] In one embodiment, the capacitance value of the first capacitor is equal to the capacitance value of the second capacitor.

[0060] In one embodiment, one end of the first capacitor is grounded, and one end of the second capacitor is grounded.

[0061] In one embodiment, as Figure 2 shown, a control method for a magnetic field intensity detection circuit is provided, which is applied to the magnetic field intensity detection circuit described in the first aspect. The method includes steps S201 to S204:

[0062] Step S201: Adjust the resistance value of the non-linear negative resistor so that the absolute value of the resistance of the non-linear negative resistor is less than the central resistance value of the positive resistor.

[0063] Step S202: Adjust the coupling distance between the first inductance coil and the second inductance coil so that the coupling distance is less than twice the diameter of the inductance coil corresponding to the first inductance coil and / or the second inductance coil.

[0064] Step S203: Obtain the resonance frequency of the magnetic field intensity detection circuit, and adjust the modulation frequency of the positive resistor to be the same as the resonance frequency of the magnetic field intensity detection circuit; wherein, the resistance value of the positive resistor changes periodically around the central resistance value.

[0065] Step S204: When the first inductance coil and the second inductance coil are in the magnetic field to be measured, obtain the voltage signal of the gain resonance unit, and determine the magnetic field intensity of the magnetic field to be measured based on the voltage signal.

[0066] The control method for the magnetic field strength detection circuit described above ensures that, in the initial state of the detection circuit, the gain resonant circuit and the loss resonant circuit are in a dynamically balanced, time-space symmetric state. The measured magnetic field intensity influences the coupling efficiency of the two resonant units, and small changes in the detected magnetic field are proportional to the cube root of the measured voltage amplitude, thereby achieving highly sensitive detection of magnetic field intensity. Furthermore, the nonlinear negative resistance contained in the gain resonant unit remains in a steady-state oscillation during the detection process, reducing noise in the measured voltage signal and producing a signal output with a high signal-to-noise ratio.

[0067] In one embodiment, a magnetic field strength detection device is provided, comprising the magnetic field strength detection circuit as described in the first aspect.

[0068] In one embodiment, Figure 3 As shown, the present application provides a magnetic field intensity detection circuit. This circuit breaks through the static limitations of traditional symmetrical circuits by dynamically matching the periodic fluctuations of a time-varying positive resistor with a nonlinear negative resistor. This circuit can achieve a cube root response characteristic to small changes in the magnetic field and voltage amplitude, thereby achieving high sensitivity and high signal-to-noise ratio magnetic field detection. The circuit includes:

[0069] Gain resonance unit 1: consists of a first inductor 11, a first capacitor 12 and a nonlinear negative resistor 13 connected in parallel;

[0070] Lossy resonance unit 2: consists of a second inductor 21, a second capacitor 22 and a periodically changing positive resistor 23 connected in parallel;

[0071] The first inductor 11 and the second inductor 21 in the gain resonance unit 1 and the loss resonance unit 2 are coaxially placed, and energy exchange between the two resonance units is performed through mutual inductive coupling, and the coupling efficiency is affected by the strength of the surrounding magnetic field.

[0072] When the circuit is in an initial state, the inductances of the first inductor 11 and the second inductor 21 are strictly equal, and the first capacitor 12 and the second capacitor 22 are strictly equal.

[0073] When the circuit is in its initial state, the absolute value of nonlinear negative resistor 13 is less than the central resistance of periodically varying positive resistor 23. The modulation frequency of periodically varying positive resistor 23 is adjusted to coincide with the circuit's resonant frequency. That is, the variation period of periodically varying positive resistor 23, T, is 1 / circuit resonant frequency, and its resistance varies in a rectangular wave-like modulation pattern around the central resistance.

[0074] The non-linear negative resistor 13 is composed of a positive feedback resistor 131, a negative feedback resistor 132, a voltage-dividing resistor 133, and an operational amplifier 134. One end of the positive feedback resistor 131 is connected to the non-inverting input terminal of the operational amplifier 134. The other end of the positive feedback resistor 131 is connected to the output terminal of the operational amplifier 134 and one end of the negative feedback resistor 132. One end of the negative feedback resistor 132 is connected to the output terminal of the operational amplifier 134. The other end of the negative feedback resistor 132 is connected to the inverting input terminal of the operational amplifier 134. One end of the voltage-dividing resistor 133 is connected to the inverting input terminal of the operational amplifier 134. The other end of the voltage-dividing resistor 133 is connected to the ground. In the working state, the operational amplifier 134 operates in the negative saturation region.

[0075] The specific working process of the above circuit is as follows:

[0076] First, adjust the resistance value of the non-linear negative resistor 13 so that the absolute value of its equivalent negative resistance is slightly less than the central resistance value of the periodically varying positive resistor 23 in the loss resonant circuit 2.

[0077] Next, adjust the coupling distance between the first inductance coil 11 of the gain resonant unit 1 and the second inductance coil 21 of the loss resonant unit 2 so that it is less than twice the diameter of the inductance coil.

[0078] Next, measure the resonant frequency of the circuit and synchronize the modulation frequency of the periodically varying positive resistor 23 to the resonant frequency of the circuit, so that the periodically varying positive resistor 23 varies periodically around the central resistance value. At this time, the detection circuit is in a dynamic time-space symmetric state.

[0079] Finally, place the two inductance coils in the magnetic field to be measured and measure the voltage V1 signal of the gain resonant unit in real time. It can be detected that the small change in the magnetic field has a cube root relationship with the change in the measured voltage V1 amplitude. When the magnetic field strength increases, the voltage V1 of the gain resonant circuit shows a significant decrease; when the magnetic field strength decreases, the voltage V1 of the gain resonant circuit shows a significant increase, thereby realizing high-sensitivity detection of the magnetic field strength.

[0080] In summary, when the detection circuit is in the initial state in this application, the gain resonant circuit and the loss resonant circuit are in a dynamically balanced time-space symmetric state. The magnetic field strength to be measured affects the coupling efficiency of the two resonant units. The small change in the magnetic field detected has a cube root relationship with the measured voltage amplitude, thereby realizing high-sensitivity detection of the magnetic field strength. At the same time, the non-linear negative resistor contained in the gain resonant unit is in a steady-state oscillation state during the detection process, reducing the noise of the measured voltage signal and forming a signal output with a high signal-to-noise ratio.

[0081] In the description of this specification, the descriptions referring to terms such as "some embodiments", "other embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0082] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0083] The above-described embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation to the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A magnetic field intensity detection circuit, characterized in that, Comprising: A gain resonance unit, including a first inductance coil, a first capacitor, and a nonlinear negative resistance; the first inductance coil, the first capacitor, and the nonlinear negative resistance are connected in parallel with each other; A loss resonance unit, including a second inductance coil, a second capacitor, and a positive resistance; the second inductance coil, the second capacitor, and the positive resistance are connected in parallel with each other; Wherein, the first inductance coil and the second inductance coil are coaxially arranged; The magnetic field intensity detection circuit determines the magnetic field intensity of the magnetic field to be measured based on the voltage signal of the gain resonance unit.

2. The magnetic field intensity detection circuit according to claim 1, characterized in that When the magnetic field intensity detection circuit is in an initial state, the absolute value of the resistance of the nonlinear negative resistance is less than the central resistance value of the positive resistance; wherein, the resistance value of the positive resistance changes periodically.

3. The magnetic field intensity detection circuit according to claim 1, characterized in that When the magnetic field intensity detection circuit is in an initial state, the modulation frequency of the positive resistance is the same as the resonance frequency of the magnetic field intensity detection circuit; wherein, the resistance value of the positive resistance changes periodically.

4. The magnetic field intensity detection circuit according to claim 1, characterized in that When the magnetic field intensity detection circuit is in an initial state, the coupling distance between the first inductance coil and the second inductance coil is less than twice the diameter of the inductance coil corresponding to the first inductance coil and / or the second inductance coil.

5. The magnetic field intensity detection circuit according to claim 1, characterized in that The nonlinear negative resistance includes a positive feedback resistor, a negative feedback resistor, a voltage dividing resistor, and an operational amplifier; wherein One end of the positive feedback resistor is connected to the non-inverting input terminal of the operational amplifier, one end of the first inductance coil, and one end of the first capacitor; the other end of the positive feedback resistor is connected to the output terminal of the operational amplifier; One end of the negative feedback resistor is connected to the inverting input terminal of the operational amplifier, and the other end of the negative feedback resistor is connected to the output terminal of the operational amplifier; One end of the voltage dividing resistor is connected to the inverting input terminal of the operational amplifier; the other end of the voltage dividing resistor is connected to the other end of the first inductance coil and the other end of the first capacitor.

6. The magnetic field intensity detection circuit according to claim 1, characterized in that The inductance value of the first inductance coil is equal to the inductance value of the second inductance coil.

7. The magnetic field intensity detection circuit according to claim 1, characterized in that The capacitance value of the first capacitor is equal to the capacitance value of the second capacitor.

8. The magnetic field intensity detection circuit according to claim 1, characterized in that One end of the first capacitor is grounded, and one end of the second capacitor is grounded.

9. A control method for a magnetic field intensity detection circuit, characterized in that Applied to the magnetic field intensity detection circuit according to any one of claims 1-8, the method includes: Adjust the resistance value of the nonlinear negative resistance so that the absolute value of the resistance of the nonlinear negative resistance is less than the central resistance value of the positive resistance; Adjust the coupling distance between the first inductance coil and the second inductance coil so that the coupling distance is less than twice the diameter of the inductance coil corresponding to the first inductance coil and / or the second inductance coil; Obtain the resonance frequency of the magnetic field intensity detection circuit, and adjust the modulation frequency of the positive resistor to be the same as the resonance frequency of the magnetic field intensity detection circuit; wherein, the resistance value of the positive resistor changes periodically around the central resistance value; When the first inductance coil and the second inductance coil are in the magnetic field to be measured, obtain the voltage signal of the gain resonance unit, and determine the magnetic field intensity of the magnetic field to be measured based on the voltage signal.

10. A magnetic field intensity detection device, characterized in that, Comprise the magnetic field intensity detection circuit according to any one of claims 1-8.

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