Magnetometer main control circuit

Abstract

The invention relates to the technical field of magnetometers, and provides a magnetometer main control circuit. The magnetometer main control circuit comprises a main controller; the digital-to-analog converter is used for receiving the digital temperature control signal and the digital constant-current control signal and performing digital-to-analog conversion; the laser temperature control circuit comprises a first power amplifier which is used for amplifying the first analog control signal and generating a first temperature control signal for controlling the temperature of the laser; the laser constant-current control circuit comprises a first operational amplifier and a laser voltage feedback circuit and is used for generating an analog constant-current control signal for controlling laser current according to the second analog control signal; and the thermostatic chamber temperature control circuit comprises a digital potentiometer and a second power amplifier, and is used for receiving the target amplitude sent by the main controller, generating a temperature control voltage with the target amplitude and outputting the temperature control voltage to the second power amplifier for amplification, so that the second power amplifier generates a second temperature control signal for controlling the temperature of the thermostatic chamber.

Description

Technical Field

[0001] The present disclosure relates to the technical field of magnetometers, and in particular to a main control circuit of a magnetometer. Background Art

[0002] Magnetometer is a basic instrument for magnetic detection and ground magnetic field observation. Its performance directly determines the accuracy of magnetic field measurement. OPM (Optical-Pumping Magnetometer) refers to a type of magnetometer that uses the optical pumping effect to polarize atoms and destroys the polarization state by applying an external radio frequency field to achieve magnetic field measurement. The polarized atoms can be cesium atoms.

[0003] The main control circuit of the magnetometer has multiple functions such as temperature control and constant current control. Each function requires the main controller to cooperate with the functional circuit corresponding to the current function. In some circuits, in order to realize multiple functions, it may be necessary to layout multiple controllers, making the circuit more complex and the circuit cost higher. Summary of the invention

[0004] In view of this, an embodiment of the present disclosure provides a magnetometer main control circuit to solve the technical problem that the circuit of the magnetometer main control circuit in the prior art is relatively complex.

[0005] To achieve the above objectives, the technical solution adopted by the present disclosure is:

[0006] The embodiment of the present disclosure provides a magnetometer main control circuit, which includes: a main controller, which is used to generate a digital temperature control signal according to the collected laser temperature, generate a digital analog constant current control signal according to the collected laser current, and set the target amplitude of the constant temperature chamber temperature control voltage; a digital-to-analog converter, which is connected to the main controller through a serial peripheral device interface SPI, and is used to receive the digital temperature control signal and the digital constant current control signal and perform digital-to-analog conversion, convert the digital temperature control signal into a first analog control signal and output it from a first analog output terminal, and convert the digital constant current control signal into a second analog control signal and output it from a second analog output terminal; the laser temperature control circuit includes a first power amplifier, the input terminal of the first power amplifier is connected to the first analog output terminal, and is used to amplify the first analog control signal to generate a control signal for the laser. a first temperature control signal for the temperature of the laser device; a laser constant current control circuit, comprising a first operational amplifier and a laser voltage feedback circuit, the non-phase input terminal of the first operational amplifier is connected to the second analog output terminal and the output terminal of the laser voltage feedback circuit, the output terminal of the first operational amplifier is connected to the positive voltage input terminal of the laser through a first output resistor, and is used to generate an analog constant current control signal for controlling the laser current according to the second analog control signal; a constant temperature chamber temperature control circuit, comprising a digital potentiometer and a second power amplifier, the digital potentiometer is connected to the main controller through SPI, and is connected to the input terminal of the second power amplifier, and is used to receive the target amplitude sent by the main controller and generate a temperature control voltage with the target amplitude, and output it to the second power amplifier for amplification, so that the second power amplifier generates a second temperature control signal for controlling the temperature of the constant temperature chamber.

[0007] In one embodiment, the magnetometer main control circuit also includes a temperature acquisition circuit for collecting temperature data, including a current bridge and a differential amplifier connected to the current bridge, one arm of the current bridge includes a thermistor arranged outside the device to be tested for measuring temperature, wherein the device to be tested is a laser or a constant temperature chamber.

[0008] In one embodiment, the differential amplifier is AD7799 or a Sigma-Delta ADC integrated in the main controller.

[0009] In one embodiment, the digital-to-analog converter is DAC80502.

[0010] In one embodiment, the first power amplifier is MAX9711; and / or the second power amplifier is MAX9711.

[0011] In one embodiment, the laser voltage feedback circuit includes a second operational amplifier, a non-inverting input terminal of the second operational amplifier is connected to the positive power supply input terminal of the laser, a negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the non-inverting input terminal of the first operational amplifier through a second output resistor.

[0012] In one embodiment, the first operational amplifier is OPA2334; and / or, the second operational amplifier is OPA2334.

[0013] In one embodiment, the current bridge includes a first resistor, a second resistor, a third resistor and a fourth resistor with the same resistance value, and the second resistor is a thermistor; the first ends of the first resistor and the third resistor are connected to a power supply, which is used to provide a regulated power supply for the current bridge; the second end of the first resistor is connected to the first end of the second resistor, the second end of the third resistor is connected to the first end of the fourth resistor, and the second ends of the second resistor and the fourth resistor are grounded; wherein the second end of the first resistor and the first end of the second resistor are connected to the in-phase input terminal of the differential amplifier, and the second end of the third resistor and the first end of the fourth resistor are connected to the inverting input terminal of the differential amplifier.

[0014] In one embodiment, the digital potentiometer is a MAX5482.

[0015] In one embodiment, the main controller comprises a STM32F3 series microcontroller.

[0016] Compared with the prior art, the beneficial effects of the embodiments of the present disclosure are as follows: the technical solution of the embodiments of the present disclosure respectively connects the laser constant current control circuit, the laser temperature control circuit and the constant temperature chamber temperature control circuit through the same main controller, and uses one main controller to realize laser constant current, temperature control and constant temperature chamber temperature control, thereby reducing the complexity of the circuit and reducing the cost of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 is a structural schematic diagram of a magnetometer main control circuit provided by an embodiment of the present disclosure;

[0019] Figure 2 is a circuit diagram of a laser temperature control circuit and a laser constant current control circuit provided by an embodiment of the present disclosure;

[0020] Figure 3 is a circuit diagram of a temperature acquisition circuit provided by an embodiment of the present disclosure;

[0021] Figure 4 is a circuit diagram of a constant temperature room control circuit provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] The disclosed embodiments will now be described more fully with reference to the accompanying drawings in which the embodiments are shown. However, the disclosed embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments specifically set forth herein; rather, the purpose of providing these embodiments is to make the disclosure exhaustive and complete and to fully convey the concepts of the embodiments to those skilled in the art so that they can implement the invention. The same reference numerals in the drawings represent the same elements, and therefore their descriptions will be omitted.

[0023] It should be understood that when an element is referred to as being connected to another element or being connected with another element, the element can be directly connected to another element, or there may be intervening elements between them. On the contrary, when an element is referred to as being directly connected to another element, there are no intervening elements.

[0024] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the disclosed embodiments belong. It should also be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant field, and unless explicitly defined as such in this article, will not be interpreted in an idealized or overly rigid sense.

[0025] The term "device" used in the embodiments may be a software component or a hardware component configured to perform a specific function. The hardware component may include a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). A software component may refer to data used by an executable code and / or data stored in an addressable storage medium and used by the executable code. Therefore, a software component may be, for example, an object-oriented software component, a class component, and a working component, and may include a process, a function, a property, a procedure, a subroutine, a program code segment, a driver, firmware, microcode, a circuit, data, a database, a data structure, a table, an array, or a variable.

[0026] The words used herein are for the purpose of describing specific embodiments and are not intended to be limiting of the present disclosure. It should be understood that the terms "include", "comprises", "comprising", "having", etc., when used in this specification, indicate the presence and characteristics, quantities, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other characteristics, quantities, steps, operations, elements, components and / or groups thereof.

[0027] The magnetometer main control circuit according to the embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0028] Figure 1 is a structural schematic diagram of a magnetometer main control circuit provided by an embodiment of the present disclosure; Figure 2 is a circuit diagram of a laser temperature control circuit and a laser constant current control circuit provided by an embodiment of the present disclosure; Figure 3 is a circuit diagram of a temperature acquisition circuit provided by an embodiment of the present disclosure; Figure 4 is a circuit diagram of a constant temperature room control circuit provided by an embodiment of the present disclosure. Figures 1 to 4 The magnetometer main control circuit provided by the embodiments of the present disclosure is described together.

[0029] like Figure 1As shown, the embodiment of the present disclosure provides a magnetometer main control circuit, which includes: a main controller 101, which is used to generate a digital temperature control signal according to the collected laser temperature, generate a digital analog constant current control signal according to the collected laser current, and set the target amplitude of the constant temperature control voltage. A digital-to-analog converter 102 is connected to the main controller through an SPI (Serial Peripheral Interface), which is used to receive the digital temperature control signal and the digital constant current control signal and perform digital-to-analog conversion, convert the digital temperature control signal into a first analog control signal and output it from the first analog output terminal, and convert the digital constant current control signal into a second analog control signal and output it from the second analog output terminal. The laser constant current control circuit 103 includes a first operational amplifier and a laser voltage feedback circuit, wherein the non-inverting input terminal of the first operational amplifier is connected to the second analog output terminal and the output terminal of the laser voltage feedback circuit, and the output terminal of the first operational amplifier is connected to the positive voltage input terminal of the laser through the first output resistor R25, and is used to generate an analog constant current control signal for controlling the laser current according to the second analog control signal; the laser temperature control circuit 104 includes a first power amplifier, wherein the input terminal of the first power amplifier is connected to the first analog output terminal, and is used to amplify the first analog control signal and generate a first temperature control signal for controlling the laser temperature; the constant temperature chamber temperature control circuit 105 includes a digital potentiometer and a second power amplifier, wherein the digital potentiometer is connected to the main controller through SPI and is connected to the input terminal of the second power amplifier, and is used to receive the target amplitude sent by the main controller and generate a temperature control voltage with the target amplitude, and output it to the second power amplifier for amplification, so that the second power amplifier generates a second temperature control signal for controlling the temperature of the constant temperature chamber.

[0030] In the disclosed embodiment, the main controller can be selected from the STM32F3 series microcontroller, which integrates 32-bit ARMCortex-M4 cores with DSP (Digital Signal Processing) and FPU (Floating Point Unitfpu) instructions, an operating frequency of 72MHz, and advanced analog peripherals, thereby improving flexibility. The series realizes embedded DSC (Digital Signal Controller) design innovation by integrating the Cortex-M4 core, fast 12-bit 5MSPS and precision 16-bit Sigma-Delta ADC (Analog-to-Digital Converter), programmable gain amplifier, fast 50ns comparator and a multi-function clock control unit with an operating frequency of 144MHz, thereby achieving optimal integration, wherein the programmable gain amplifier has 4-speed gain and an accuracy of 1%. It includes a series of 32-bit products with high performance, real-time functions, digital signal processing, low power consumption and low voltage operation characteristics, while also maintaining the characteristics of high integration and easy development. The unparalleled and complete range of STM32 products are based on industry standard cores and provide a large number of tools and software options, making this series of products an ideal choice for small projects and complete platforms. The technical solution of the disclosed embodiment can use the STM32F373CCT6 of this series as the processor, which has 256KBFlash, 72MHzCPU, MPU (Microprocessor Unit), 16-bit ADC and comparator, which can meet all the peripheral requirements of the design.

[0031] like Figure 2 As shown, the digital-to-analog converter may be DAC80502DRXR of the DAC80502 series, but is not limited thereto.

[0032] like Figure 1 As shown in FIG. 1 , the main controller outputs a digital temperature control signal to the digital-to-analog converter via SPI. Figure 2 As shown, the output pin VOUTA of the digital-to-analog converter DAC80502DRXR is the first analog output terminal, which is connected to the pin IN of the first power amplifier. The first power amplifier is used to amplify the first analog control signal DAC1 and input it into the semiconductor refrigeration chip to drive the semiconductor refrigeration chip to cool or heat the laser.

[0033] The first power amplifier can be implemented using the power amplification function of the audio amplifier MAX9711. The MAX9711 is a stereo / mono 3W BTL (Bridge-Tied Load) audio power amplifier. The device complies with the PC99 / 01 standard and uses a single 4.5V to 5.5V power supply. It has an industry-leading 100dB PSRR (Power Supply Rejection Ratio), which allows the device to operate in a noisy power supply environment without the need for an additional high-cost power supply. The ultra-low 0.005% total harmonic distortion plus noise ensures low-noise and low-distortion amplification of the audio signal, while the proprietary click / pop suppression circuit eliminates transient noise when the power is turned on and off. Its energy-saving features include: an offset voltage as low as 2mV to minimize the DC current through the speaker, a supply current as low as 7mA, and a current of 0.5pA in shutdown mode. The mute function can quickly turn the output on or off. The device features thermal-overload protection and operates over the -40°C to +85°C extended temperature range.

[0034] The MAX9711 is powered by a single 5V power supply and has an internally generated, power-independent, ground-referenced 2.5V common-mode bias voltage. By inputting different voltage values, the MAX9711 will output positive and negative voltages between the positive and negative output terminals to drive the semiconductor refrigeration chip for cooling or heating.

[0035] Specifically, the output pin VOUTA of DAC80502DRXR outputs the first analog control signal DAC1, and the pin SPI2C is grounded, which means that the pin selects the SPI mode between the two transmission modes of the serial interface SPI and I2C (Inter-Integrated Circuit). Pin SDIN / SDA is the signal input terminal in the SPI mode. The digital temperature control signal output by the main controller is input to DAC80502DRXR via pin SDIN / SDA for digital-to-analog conversion to obtain the first analog control signal. The first analog control signal is input via pin IN of MAX9711, and is output to the power supply terminal of the semiconductor cooling plate by the positive output terminal OUT+ and the negative output terminal OUT- of MAX9711.

[0036] like Figure 2 As shown, the output pin VOUTB of the digital-to-analog converter DAC80502DRXR is the second analog output terminal, which is connected to the non-inverting input terminal of the first operational amplifier U7A, and the second analog control signal DAC2 is input to the non-inverting input terminal of the first operational amplifier U7A. Figure 2 The PDD shown is connected to a laser.

[0037] The laser constant current control circuit includes a first operational amplifier U7A and a laser voltage feedback circuit. The laser voltage feedback circuit includes a second operational amplifier U7B, the positive phase input terminal of the second operational amplifier is connected to the positive power input terminal of the laser, the negative phase input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the positive phase input terminal of the first operational amplifier through a second output resistor R24.

[0038] In the embodiment of the present disclosure, the first operational amplifier U7A may be OPA2334, but is not limited thereto; the second operational amplifier may also be OPA2334, but is not limited thereto.

[0039] The digital constant current control signal output by the main controller is converted into digital-to-analog by DAC80502DRXR to obtain a second analog control signal. The second analog control signal is input via the non-inverting input terminal of the first operational amplifier and output from the output terminal of the second operational amplifier to the positive power input terminal of the laser.

[0040] The main controller controls the digital-to-analog converter to output analog voltage through SPI. The analog voltage forms a closed loop through the first operational amplifier and the laser voltage feedback, so that the laser constant current control circuit outputs a constant current. The analog voltage value is positively correlated with the laser current, thereby realizing constant current control of the laser.

[0041] like Figure 3 As shown, the magnetometer main control circuit also includes a temperature acquisition circuit for collecting temperature data, including a current bridge and a differential amplifier connected to the current bridge, one arm of the current bridge includes a thermistor arranged outside the device to be tested for measuring temperature, wherein the device to be tested is a laser or a constant temperature chamber.

[0042] like Figure 3 As shown, the current bridge includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 with the same resistance, and the second resistor R2 is a thermistor; the first ends of the first resistor R1 and the third resistor R3 are connected to the power supply VCC, which is used to provide a regulated power supply for the current bridge; the second end of the first resistor R1 is connected to the first end of the second resistor R2, the second end of the third resistor R3 is connected to the first end of the fourth resistor R4, and the second ends of the second resistor R2 and the fourth resistor R4 are grounded; wherein, the second end of the first resistor R1 and the first end of the second resistor R2 are connected to the in-phase input terminal ADCIN+ of the differential amplifier, and the second end of the third resistor R3 and the first end of the fourth resistor R4 are connected to the inverting input terminal ADCIN- of the differential amplifier.

[0043] When the current bridge is in a balanced state, no current flows through the two diagonals of the current bridge, and when the current bridge is unbalanced, current flows through. The first resistor R1, the third resistor R3, and the fourth resistor R4 are all fixed resistors, so the resistance value of the second resistor R2 can be calculated by measuring the current.

[0044] In the embodiment of the present disclosure, the differential amplifier is AD7799 or a Sigma-Delta ADC integrated in the main controller.

[0045] Temperature acquisition circuits such as laser temperature acquisition circuit and constant temperature room temperature acquisition circuit use current bridge to collect the change of electrical signal caused by the change of resistance value of thermistor with temperature change, and provide real-time feedback data as closed-loop control. The feedback data can use external high-performance ADC chip as analog-to-digital conversion and differential amplification. When the ADC chip is an external chip, the main controller can read the digital conversion result output by the ADC chip through the SPI interface and calculate the measured temperature based on the digital conversion result.

[0046] In the technical solution of the embodiment of the present disclosure, the temperature acquisition circuit may further include a main controller temperature acquisition circuit, and the temperature acquisition circuit may use the built-in ADC of the main controller to convert and calculate the temperature.

[0047] The three temperature information acquisition circuits are all realized through thermistor temperature measurement principle. Thermistors are sensitive to temperature and have different resistance values ​​at different temperatures. When voltage is applied to the circuit, the temperature changes, that is, the voltage changes. Usually, the temperature characteristics of thermistors are known, and the current temperature can be obtained by measuring and calculating the voltage.

[0048] like Figure 3 As shown, the input end of the differential amplifier A1 is connected to the current bridge. Specifically, the non-inverting input end ADCIN+ of the differential amplifier A1 can be connected to the second end of the first resistor R1 and the first end of the second resistor R2, and the inverting input end ADCIN- of the differential amplifier can be connected to the second end of the third resistor R3 and the first end of the fourth resistor R4. The differential amplifier is used to amplify the voltage change value of the second resistor R2, such as by x times, where the specific amplification factor indicated by x can be set according to the actual application scenario and is not specifically limited here. The differential amplifier A1 can be AD7799, but is not limited to this.

[0049] The AD7799 is a low-power, low-noise, complete analog front end suitable for high-precision measurement applications. It has a built-in low-noise 24-bit Σ-Δ ADC, which contains 3 differential analog inputs and an on-chip low-noise instrumentation amplifier, so small signals can be directly input. The root mean square (RMS) noise of the AD7799 is 27nV. The AD7799 on-chip features include a low-end power switch, reference voltage detection, programmable digital output pins, fuse current control, and an internal clock oscillator. The output data rate can be set by software programming and can vary from 4.17Hz to 470Hz.

[0050] In addition, the differential amplifier can be a Sigma-Delta ADC integrated in the main controller. Sigma-Delta ADC is a Σ-Δ digital-to-analog converter, which can be referred to as SDADC. It consists of an analog modulator and a downsampling decimation filter. It samples the input signal at a sampling frequency much higher than the Nyquist frequency. The sampled signal is converted into a low-bit, high-bitrate digital signal stream after being processed by the modulator. Sigma-Delta ADC can reduce the design requirements for analog circuits by adopting oversampling, noise shaping and digital filtering technology, and achieve high precision and low power consumption that other types of ADCs cannot achieve.

[0051] like Figure 4 As shown, the digital potentiometer may be MAX5482. The second power amplifier may be MAX9711, but is not limited thereto. Figure 1 and Figure 4 As shown, different tap positions can be written to the digital potentiometer through SPI, the H terminal is connected to the signal source, the L terminal is grounded, and the tap terminal W outputs the second temperature control signal after amplitude modulation. Figure 4 As shown, the technical solution of the embodiment of the present disclosure uses a digital potentiometer MAX5482 to modulate a sinusoidal signal with a fixed frequency and amplitude and then output it to MAX9711. The input end of the second power amplifier MAX9711 is a sinusoidal signal with a fixed frequency and a variable amplitude.

[0052] According to the magnetometer main control circuit provided by the embodiment of the present disclosure, the laser constant current control circuit, the laser temperature control circuit and the constant temperature chamber temperature control circuit are respectively connected through the same main controller, and the laser constant current, temperature control and constant temperature chamber temperature control are realized by using one main controller, thereby reducing the complexity of the circuit and reducing the cost of the circuit.

[0053] The above are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A magnetometer main control circuit, characterized in that: The magnetometer main control circuit comprises: A main controller, used to generate a digital temperature control signal according to the collected laser temperature, generate a digital analog constant current control signal according to the collected laser current, and set a target amplitude of a constant temperature chamber temperature control voltage; A digital-to-analog converter, connected to the main controller via a serial peripheral interface SPI, for receiving the digital temperature control signal and the digital constant current control signal and performing digital-to-analog conversion, converting the digital temperature control signal into a first analog control signal and outputting it from a first analog output terminal, and converting the digital constant current control signal into a second analog control signal and outputting it from a second analog output terminal; The laser temperature control circuit comprises a first power amplifier, wherein the input end of the first power amplifier is connected to the first analog output end, and is used to amplify the first analog control signal to generate a first temperature control signal for controlling the laser temperature; A laser constant current control circuit, comprising a first operational amplifier and a laser voltage feedback circuit, wherein a non-inverting input terminal of the first operational amplifier is connected to the second analog output terminal and the output terminal of the laser voltage feedback circuit, and the output terminal of the first operational amplifier is connected to a positive voltage input terminal of the laser through a first output resistor, and is used to generate an analog constant current control signal for controlling the laser current according to the second analog control signal; A constant temperature chamber temperature control circuit comprises a digital potentiometer and a second power amplifier, wherein the digital potentiometer is connected to the main controller via the SPI and is connected to the input end of the second power amplifier, and is used to receive the target amplitude and generate a temperature control voltage having the target amplitude, and output the voltage to the second power amplifier for amplification, so that the second power amplifier generates a second temperature control signal for controlling the temperature of the constant temperature chamber.

2. The magnetometer main control circuit according to claim 1, characterized in that: The magnetometer main control circuit also includes a temperature acquisition circuit for collecting the temperature data, including a current bridge and a differential amplifier connected to the current bridge, one arm of the current bridge includes a thermistor arranged outside the device to be tested for measuring temperature, wherein the device to be tested is a laser or a constant temperature chamber.

3. The magnetometer main control circuit according to claim 1, characterized in that: The differential amplifier is AD7799 or a Sigma-Delta ADC integrated in the main controller.

4. The magnetometer main control circuit according to claim 1, characterized in that: The digital-to-analog converter is DAC80502.

5. The magnetometer main control circuit according to claim 1, characterized in that: The first power amplifier is MAX9711; and / or the second power amplifier is MAX9711.

6. The magnetometer main control circuit according to claim 1, characterized in that: The laser voltage feedback circuit includes a second operational amplifier, a non-phase input terminal of the second operational amplifier is connected to the positive power supply input terminal of the laser, a negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the non-phase input terminal of the first operational amplifier through a second output resistor.

7. The magnetometer main control circuit according to claim 6, characterized in that: The first operational amplifier is OPA2334; and / or the second operational amplifier is OPA2334.

8. The magnetometer main control circuit according to claim 1, characterized in that: The current bridge includes a first resistor, a second resistor, a third resistor and a fourth resistor with the same resistance value, the second resistor is the thermistor; the first ends of the first resistor and the third resistor are connected to a power supply, used to provide a regulated power supply for the current bridge; the second end of the first resistor is connected to the first end of the second resistor, the second end of the third resistor is connected to the first end of the fourth resistor, and the second ends of the second resistor and the fourth resistor are grounded; wherein the second end of the first resistor and the first end of the second resistor are connected to the in-phase input terminal of the differential amplifier, and the second end of the third resistor and the first end of the fourth resistor are connected to the inverting input terminal of the differential amplifier.

9. The magnetometer main control circuit according to claim 1, characterized in that: The digital potentiometer is MAX5482.

10. The magnetometer main control circuit according to claim 1, characterized in that: The main controller includes an STM32F3 series microcontroller.

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