CN113933574B - Signal processing circuit for reducing low-frequency noise of magnetoresistive sensor - Google Patents
Signal processing circuit for reducing low-frequency noise of magnetoresistive sensor Download PDFInfo
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- CN113933574B CN113933574B CN202111144883.XA CN202111144883A CN113933574B CN 113933574 B CN113933574 B CN 113933574B CN 202111144883 A CN202111144883 A CN 202111144883A CN 113933574 B CN113933574 B CN 113933574B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/02—Measuring effective values, i.e. root-mean-square values
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/04—Measuring peak values or amplitude or envelope of ac or of pulses
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
- G01R33/0029—Treating the measured signals, e.g. removing offset or noise
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/096—Magnetoresistive devices anisotropic magnetoresistance sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/09—Magnetoresistive devices
- G01R33/098—Magnetoresistive devices comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
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Abstract
The invention relates to a signal processing circuit for reducing low-frequency noise of a magneto-resistive sensor, which comprises a modulation and demodulation circuit module and a digital filtering module, wherein the circuit power consumption is reduced by modulating a magneto-resistive sensor power supply, the manufacturing process cost is reduced, the defects of high power consumption, high cost and the like of modulating sensor output by a modulating coil in the market are overcome, the low-frequency noise of the magneto-resistive sensor is effectively reduced by combining the digital filtering module, and the application range of the magneto-resistive sensor is enlarged.
Description
Technical Field
The invention belongs to the technical field of electronic circuits, and relates to a signal processing circuit for reducing low-frequency noise of a magnetoresistive sensor.
Background
Nowadays, magneto-resistive sensors are widely used in the fields of current detection, hard disk storage, inertial measurement and the like, and when the magneto-resistive sensors such as giant magneto-resistive (GMR) sensors or magnetic tunnel junction (TMR) sensors are used for current detection, low-frequency noise can greatly influence the detection precision during measurement, and a modulation-demodulation technology can be used for modulating the working point of the sensor outside a low-frequency noise section so as to achieve the effect of noise reduction.
At present, the method for modulating and demodulating the sensor at home and abroad mainly adopts direct modulation of the output signal of the sensor, for example, the invention patent of publication No. CN110869788A directly modulates the output of the sensor to shift the working point of the sensor to be out of a low-frequency noise region so as to achieve the aim of reducing the magnetic resistance sensing noise, but the invention does not explain the specific implementation mode of modulation, and if a special modulation coil is designed to be arranged at the bottom of the sensor to modulate the output of the sensor, the PCB manufacturing process is complex, the cost is high, and the power consumption of a required modulation driving circuit is larger.
Therefore, there is a need for a more efficient implementation of a modem signal processing circuit that reduces low frequency noise of a magnetoresistive sensor, with simple manufacturing process, low power consumption, and easy implementation.
Disclosure of Invention
The invention aims to overcome the defects of the existing circuit for reducing the low-frequency noise of a magneto-resistance sensor, and provides a signal processing circuit for reducing the low-frequency noise of the magneto-resistance sensor, which can remarkably reduce the low-frequency noise of an application circuit of the magneto-resistance sensor.
The invention comprises a modulation and demodulation circuit module and a digital filtering module; the modulation mode of the circuit is to modulate the power supply of the sensor, so that the driving power consumption can be effectively reduced, and the manufacturing process is simple;
the modulation and demodulation circuit module comprises a signal generation module, a modulation driving module, an instrument amplification module and a lock-in amplification module; the digital filtering module comprises an analog-to-digital conversion module, a frequency discrimination module and an MCU main control module;
The signal generation module comprises a digital frequency synthesizer, and the MCU main control module is used for controlling the digital frequency synthesizer to generate a sine wave modulation sensor power supply with a required frequency;
the modulation driving module comprises an operational amplifier, and amplifies a modulation signal to drive the sensor to work;
The instrument amplification module comprises an instrument amplifier and is used for amplifying the output voltage of the sensor and reducing zero drift;
The lock-in amplifying module comprises a lock-in amplifier, demodulates the modulated signal output by the instrument amplifier and recovers the original sensor signal.
The analog-to-digital conversion module comprises a high-precision ADC (analog-to-digital converter), converts the demodulated sensor signal into a digital signal and outputs the digital signal to the MCU main control module;
The frequency discrimination module comprises a voltage comparator and a frequency discriminator, wherein the voltage comparator converts a demodulated sensor signal into a same-frequency TTL level and transmits the same-frequency TTL level to the frequency discriminator, and the frequency discriminator converts the signal frequency into a voltage signal and outputs the voltage signal to the MCU main control module;
the MCU master control module comprises a master control chip and a basic peripheral circuit thereof, an ADC (analog-to-digital converter) in the MCU master control module transmits a digital signal to the MCU master control module, and the MCU master control module samples the output of the frequency discriminator and calculates the signal frequency;
The main control chip combines the signal frequency and the sampling value of the ADC (analog-to-digital converter) to carry out digital average of the in-phase point for inhibiting the white noise of the system.
The invention can effectively reduce the power consumption of a modulation driving circuit by modulating the power supply of the magneto-resistance sensor through the signal generating module, does not need to manufacture a modulation coil with complex process, greatly reduces the manufacturing cost, and can obviously reduce the low-frequency noise of the magneto-resistance sensor by combining with the digital filtering module.
Further, the signal processing circuit for reducing the low-frequency noise of the magneto-resistive sensor can be a signal processing circuit of an open-loop magneto-resistive sensor or a signal processing circuit of a closed-loop magneto-resistive sensor.
Further, the signal processing circuit for reducing the low-frequency noise of the magneto-resistance sensor measures the magnetic field signal through the magneto-resistance sensor, and can also measure the current signal or the magnetic field signal change caused by other physical quantities through the magneto-resistance sensor.
Further, the magneto-resistance sensor is a giant magneto-resistance sensor, an anisotropic magneto-resistance sensor or a tunnel junction magneto-resistance sensor.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be further described with reference to the accompanying drawings, and it is obvious that the described embodiments are only some of the embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in FIG. 1, a signal processing circuit for reducing low-frequency noise of a magneto-resistive sensor comprises a magneto-resistive sensor 1-1, an operational amplifier 1-2, an instrument amplifier 1-3, a lock-in amplifier 1-4, a voltage comparator 1-5, a signal generating module 1-6, a main control module 1-7, an analog-to-digital conversion module 1-8 and a frequency discrimination module 1-9.
The magneto-resistance sensor 1-1 is a TMR sensor and is used for converting a magnetic field signal generated by current into a voltage signal, the signal generation module 1-6 outputs a high-frequency modulation signal and generates a driving voltage through the operational amplifier 1-2 to supply power for the TMR sensor, at the moment, the voltage signal output by the TMR sensor is modulated into the high-frequency signal and is transmitted to the instrumentation amplifier 1-3 for amplification, and the lock-in amplifier 1-4 demodulates the modulated signal to recover an original signal. The analog-to-digital conversion module 1-8 carries out digital sampling on the recovered original signal, converts the voltage signal into digital quantity, the voltage comparator 1-5 converts the recovered sinusoidal signal into TTL level and outputs the TTL level to the frequency discriminator 1-9, the frequency discriminator converts the signal frequency into voltage and transmits the voltage to the main control module 1-7, the ADC (analog-to-digital converter) in the main control module collects and calculates the signal frequency of the voltage, meanwhile, the MCU main control module controls the sampling rate of the analog-to-digital conversion module 1-8 according to the signal frequency, the sampling rate is controlled to be designed to collect fixed points of each period of the signal, then a plurality of periods are collected, digital average is carried out on the points with the same phase, the signal noise is further reduced, and finally information such as the effective value, the peak-to-peak value and the frequency of the original current signal is calculated.
According to the process, the circuit provided by the invention has the function of reducing the low-frequency noise of the magneto-resistance sensor, and obviously reduces the circuit power consumption and the process cost.
Claims (3)
1. A signal processing circuit for reducing low frequency noise of a magnetoresistive sensor, comprising: the system comprises a modulation and demodulation circuit module and a digital filtering module; the modulation and demodulation circuit module comprises a signal generation module, a modulation driving module, an instrument amplification module and a lock-in amplification module; the digital filtering module comprises an analog-to-digital conversion module, a frequency discrimination module and an MCU main control module;
The signal generation module comprises a digital frequency synthesizer, and the MCU is used for controlling the digital frequency synthesizer to generate a sine wave modulation sensor power supply with a required frequency; the modulation driving module comprises an operational amplifier, and amplifies the modulation signal to drive the sensor to work; the instrument amplification module comprises an instrument amplifier and is used for amplifying the output voltage of the sensor and reducing zero drift; the lock-in amplifying module comprises a lock-in amplifier, demodulates a modulation signal output by the instrument amplifier and recovers an original sensor signal;
The analog-to-digital conversion module comprises a high-precision ADC, converts the demodulated sensor signal into a digital signal and outputs the digital signal to the MCU main control module; the frequency discrimination module comprises a voltage comparator and a frequency discriminator, wherein the voltage comparator converts a demodulated sensor signal into a same-frequency TTL level and transmits the same-frequency TTL level to the frequency discriminator, and the frequency discriminator converts the signal frequency into a voltage signal and outputs the voltage signal to the MCU main control module; the MCU master control module comprises a master control chip and a basic peripheral circuit thereof, the analog-to-digital converter transmits digital signals to the MCU master control module, and meanwhile, the MCU master control module samples the output of the frequency discriminator and calculates the signal frequency; the main control chip combines the signal frequency and the sampling value of the analog-to-digital conversion module to carry out digital average of the in-phase point for inhibiting the white noise of the system.
2. A signal processing circuit for reducing low frequency noise of a magnetoresistive sensor as claimed in claim 1 wherein: is a signal processing circuit of an open loop magnetic resistance sensor or a signal processing circuit of a closed loop magnetic resistance sensor.
3. A signal processing circuit for reducing low frequency noise of a magnetoresistive sensor as claimed in claim 1 wherein: the magnetic field signal can be measured by a magneto-resistive sensor, and the magnetic field signal change caused by a current signal or other physical quantity can be measured by a magneto-resistive sensor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111144883.XA CN113933574B (en) | 2021-09-28 | 2021-09-28 | Signal processing circuit for reducing low-frequency noise of magnetoresistive sensor |
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| CN202111144883.XA CN113933574B (en) | 2021-09-28 | 2021-09-28 | Signal processing circuit for reducing low-frequency noise of magnetoresistive sensor |
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| CN113933574A CN113933574A (en) | 2022-01-14 |
| CN113933574B true CN113933574B (en) | 2024-07-02 |
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| CN115327202B (en) * | 2022-07-08 | 2023-11-14 | 珠海多创科技有限公司 | TMR current sensor |
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| CN216013488U (en) * | 2021-09-28 | 2022-03-11 | 杭州电子科技大学 | Noise modulation and demodulation circuit of magnetic resistance sensor |
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| DE112005002091T5 (en) * | 2004-09-10 | 2007-07-19 | Quantum Applied Science & Research Inc., San Diego | Amplifier circuit and method for reducing voltage and current noise |
| US8829901B2 (en) * | 2011-11-04 | 2014-09-09 | Honeywell International Inc. | Method of using a magnetoresistive sensor in second harmonic detection mode for sensing weak magnetic fields |
| KR101480604B1 (en) * | 2013-04-23 | 2015-01-08 | 주식회사 엘지씨엔에스 | Apparatus and method for controlling Noise of financial apparatus |
| FR3067116B1 (en) * | 2017-06-02 | 2019-07-12 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | SYSTEM AND METHOD FOR LOW FREQUENCY NOISE REMOVAL OF MAGNETO-RESISTIVE MAGNETORESISTENCE TUNNEL SENSORS |
| CN108414951B (en) * | 2018-03-13 | 2023-06-30 | 武汉嘉晨电子技术有限公司 | Method and device for periodically modulating sensitivity of magnetic sensor to reduce noise of device |
| CN111413654B (en) * | 2020-04-14 | 2021-05-18 | 华中科技大学 | System and method for reducing noise of tunnel magneto-resistance sensor |
| CN112698253B (en) * | 2020-12-11 | 2023-09-29 | 哈尔滨工程大学 | Digital triaxial TMR magnetic sensing system |
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