Magnetoresistive relaxation oscillator magnetometer

Abstract

To rapidly measure the magnitude of an external magnetic field.SOLUTION: A magnetoresistive relaxation oscillator magnetometer (1) includes: a capacitor (2); a charge resistor (3); a discharge resistor (4); a charge / discharge switch (5); a high voltage source terminal (6); a grounding terminal (7); and a signal output terminal (Vout). The charge resistor (3) comprises at least one charge magnetoresistive unit, and the discharge resistor (4) comprises at least one discharge magnetoresistive unit. The charge / discharge switch (5) is connected to the high voltage source terminal (6) and the high voltage source terminal (6) charges the capacitor (2) via the charge resistor (3) in a charge state, and the charge / discharge switch (5) is connected to the grounding terminal (7) and the capacitor (2) discharges electricity via the grounding terminal (7) by the discharge resistor (4) during a discharge stage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to the technical field of magnetic sensors, and in particular to magnetoresistive relaxation oscillator magnetometers. [Background technology]

[0002] The magnetoresistive sensor has 1 / f noise when it is normally used. To develop low-noise magnetoresistive sensors, which can reduce the noise of the sensors, improve the accuracy of the measurement of magnetic signals. It is very important.

[0003] In general, magnetoresistive sensors have high 1 / f noise at low frequencies and mainly thermal noise at high frequencies. However, the noise energy density is much lower than that at low frequencies. Therefore, currently, the magnetic signal is modulated into a high-frequency magnetic field and then detected by a magnetoresistive sensor. It measures the high frequency magnetic field and outputs a high frequency voltage signal, then performs demodulation to extract the The aim is to move the measurement of magnetic signals from the 1 / f noise to the high frequency zone and reduce the 1 / f noise energy density. Realization is the most common choice.

[0004] However, existing high-frequency magnetic signal measuring devices usually have complicated structures and low frequency It has a wavenumber response. Summary of the Invention [Means for solving the problem]

[0005] One embodiment of the present disclosure is a magnetoresistive relaxation oscillator magnetic field for achieving rapid measurement of an external magnetic field. A force gauge is provided.

[0006] One embodiment of the present disclosure includes a capacitor, a charging resistor, a discharging resistor, and a charging / discharging switch. a high voltage supply terminal, a ground terminal, and a signal output terminal. The charging resistor comprises at least one charging magnetoresistance unit, and the discharging resistor comprises , consisting of at least one discharge magnetoresistance unit.

[0007] The first end of the capacitor is connected to the ground terminal, and the second end of the capacitor is connected to the charging / discharging terminal. The charge resistor, discharge resistor, and signal output terminal are connected to the switch, respectively. The discharge switch is further connected to the high voltage supply terminal.

[0008] During the charging phase, the charge / discharge switch is switched to the high voltage source terminal, which is connected to the charging The capacitor is charged through a resistor, while during the discharge phase the charge / discharge switch is connected to the ground terminal. The resistor is switched so that the capacitor discharges to ground.

[0009] When an external magnetic field causes a resistance change in the charging and discharging resistors, The charging and discharging time of the capacitor changes, and the pulse signal output by the signal output terminal changes depending on the charging The signal processing circuit includes one or more harmonics of the resistor or discharge resistor, and detects the external magnetic field. To measure, a pulse signal is measured.

[0010] The magnetoresistive relaxation oscillator magnetometer provided by this embodiment of the present disclosure allows for periodic charging and discharging. The discharge is carried out by employing a capacitor, a charging resistor, and a discharging resistor; The charge / discharge cycle is directly proportional to the product of the capacitance and the charge / discharge resistance. The resistance is converted to charge and discharge pulse voltages as a function of time within the charge and discharge cycle. Therefore, the measurement time can be shortened, the signal-to-noise ratio is reduced, and the structure is simplified. It is.

[0011] In order to more clearly describe the embodiments of the present disclosure or the technical solutions in the prior art, The accompanying drawings used to describe the embodiments or prior art are briefly introduced below. The accompanying drawings in the description are illustrative of certain embodiments of the present disclosure. Basic overview of device structure, driving method, and manufacturing method disclosed and suggested by the embodiments It will be apparent to one skilled in the art that the concept can be expanded and extended to other structures and drawings. There are, and they are no doubt within the scope of the claims of this disclosure. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of the charging of FIG. 1. [Diagram 3] FIG. 2 is a schematic diagram of the discharge of FIG. 1. [Figure 4] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Diagram 5] 2 is a schematic graph of the voltage Vc(t) across the capacitor and the voltage VR2(t) across the discharge resistor in FIG. 1; [Figure 6] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Figure 7] FIG. 7 is a schematic diagram of the charging of FIG. [Figure 8] FIG. 7 is a schematic diagram of the discharge of FIG. 6. [Figure 9] 7 is a schematic graph of the voltage Vc(t) across the capacitor in FIG. 6. [Figure 10] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Figure 11] FIG. 11 is a schematic diagram of the charging of FIG. [Figure 12] FIG. 11 is a schematic diagram of the discharge of FIG. [Figure 13] FIG. 11 is a circuit diagram of the equivalent trigger of FIG. [Figure 14] 11 is a schematic graph of the voltage Vc(t) and the voltage Vout(t) of the capacitor at the output terminal of the trigger in FIG. 10; [Figure 15] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Figure 16] FIG. 16 is a schematic diagram of the charging of FIG. [Figure 17] FIG. 16 is a schematic diagram of the discharge of FIG. [Figure 18] FIG. 16 is a circuit diagram of the equivalent trigger of FIG. 15. [Figure 19] 16 is a schematic graph of the voltage Vc(t) and the voltage Vout(t) of the capacitor at the output terminal of the trigger in FIG. 15. [Figure 20] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Figure 21] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Figure 22] FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer provided in accordance with one embodiment of the present disclosure. [Diagram 23] 1 is a graph of four typical signal outputs of a relaxation oscillator magnetometer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the technical solutions of the present disclosure are The solutions will be more clearly and easily understood by practice with reference to the accompanying drawings in the embodiments of the present disclosure. The embodiments described in detail below are part of the embodiments of the present disclosure and all the implementations are included. It is clear that the present disclosure does not disclose or suggest the embodiments. All other embodiments that a person skilled in the art can obtain based on the basic concept described herein fall within the scope of protection of the present invention.

[0014] One embodiment of the present disclosure includes a capacitor, a charging resistor, a discharging resistor, and a charging / discharging switch. a high voltage supply terminal, a ground terminal, and a signal output terminal. The charging resistor comprises at least one charging magnetoresistance unit, and the discharging resistor comprises , at least one discharge magnetoresistance unit. The first end of the capacitor is connected to a ground terminal The second end of the capacitor is connected to the charge resistor and the discharge resistor via the charge / discharge switch. The charge / discharge switch is connected to the high voltage source terminal. During the charging phase, the charge / discharge switch is switched to the high voltage supply terminal, The terminal charges the capacitor through the charging resistor, while during the discharge phase the charge / discharge switch , is switched to the ground terminal, so that the capacitor is discharged to the ground terminal through the discharge resistor. An external magnetic field induces resistance changes in the charging and discharging resistors. When the capacitor is turned on, the charge and discharge time of the capacitor changes, and the pulse signal output by the signal output terminal becomes , one or more harmonics of the charging resistor or the discharging resistor, and the signal processing circuitry A pulse signal is measured to measure the magnetic field.

[0015] Optionally, the charge magnetoresistive unit and the discharge magnetoresistive unit are anisotropic magnetoresistive units. The magnetoresistance units are magnetoresistance units, giant magnetoresistance units, or tunnel magnetoresistance units.

[0016] The magnetoresistive relaxation oscillator magnetometer provided by this embodiment of the present disclosure allows for periodic charging and discharging. The discharge is carried out by employing a capacitor, a charging resistor, and a discharging resistor; The charge and discharge cycle is directly proportional to the product of the capacitance of the capacitor and the resistance of the charge and discharge resistor. Therefore, the charge-discharge resistance depends on the time of the charge-discharge cycle, the charge pulse voltage and It is converted into a discharge pulse voltage. Therefore, the measurement time can be shortened and the signal-to-noise ratio can be improved. The ratio is lower and the structure is simple.

[0017] The above is the core concept of the present disclosure, and the technical solutions in the embodiments of the present disclosure include: The following description will be made in detail and completely with reference to the accompanying drawings in the embodiments of the present disclosure. All other embodiments that a person skilled in the art can obtain based on the embodiments in this disclosure without technical effort are It belongs to the protection scope of the present invention.

[0018] Referring to FIG. 1, a schematic diagram of one embodiment of a magnetoresistive relaxation oscillator magnetometer of the present disclosure is provided. The magnetoresistive relaxation oscillator magnetometer 1 includes a capacitor 2, a charging resistor 3, and a discharging resistor 4. , a charge / discharge switch 5, a high voltage power supply terminal 6, a ground terminal 7, and a signal output terminal Vout. The charging resistor 3 comprises at least one charging magnetoresistance unit, and the discharging resistor 4 The first end of the capacitor 2 is connected to the Optionally, the charge / discharge switch 5 is a metal oxide semiconductor field effect transistor The second end of the capacitor 2 and the second end of the charging resistor 3 are connected to Both are connected to the gate of the MOSFET 5, and the discharge resistor 4 is connected to the drain of the MOSFET 5. and a ground terminal 7, and a high voltage source terminal 6 is located between the first end of the charging resistor 3 and the ground terminal and the source of the MOSFET 5. The two ends of the capacitor 2 are connected to the signal output terminal Vout.

[0019] In this embodiment, the capacitor 2 is located between the gate of the MOSFET 5 and the ground terminal 7. The charging resistor 3 is located between the high voltage supply terminal 6 and the gate of the MOSFET 5. As shown in FIG. 1, during the charging phase, the charge / discharge switch 5 is switched to the high voltage supply terminal 6, That is, the MOSFET 5 is turned off and the charge / discharge switch 5 is cut off from the high voltage power supply terminal 6. The high voltage source terminal 6 is connected to the charging resistor 3 in the path of the charging branch as shown by the arrow. During the discharge phase, the capacitor 2 is charged via the charge / discharge switch 5 is switched to the ground terminal 7, i.e., the MOSFET 5 is turned on and the charge / discharge switch The capacitor 5 is connected to the ground terminal 7, and the capacitor 2 is connected to the discharge branch as shown by the arrow. The discharge path is then discharged to the ground terminal 7 via the discharge resistor 4 .

[0020] An external magnetic field is applied to the magnetometer 1 and during the charging phase, the external magnetic field changes the resistance of the charging resistor 3. During the discharge phase, a resistance change is induced in the discharge resistor 4 by the external magnetic field. During the charging phase, the signal output The charge pulse voltage signal is output by the charge resistor. During the discharge phase, the signal output terminal outputs a discharge pulse voltage signal, The pulse voltage signal contains one or more harmonics of the discharge resistor. The pulse signal at the signal output terminal is measured to measure the magnitude of the field.

[0021] In another embodiment, the charge / discharge switch 5 as shown in FIG. The second end of the capacitor 2 and the second end of the charging resistor 3 are both connected to the base of the triode 5. The discharge resistor 4 is located between the emitter of the triode 5 and the ground terminal 7, and is connected to the high voltage source terminal 6. are connected to a first end of the charging resistor 3 and to the collector of the triode 5, respectively.

[0022] Optionally, the charging resistor and the discharging resistor are opposite in the magnetic field sensing direction to provide a higher sensitivity. The resistance is the same when no external magnetic field is applied, and the resistance is the same when no external magnetic field is applied. forming a pull-type magnetoresistor. Optionally, the charging resistor is a magnetic field sensitive magnetoresistance unit.

[0023] FIG. 5 shows the voltage Vc(t) across the capacitor in magnetometer 1 and the voltage Vc(t) across the discharge resistor. Voltage V R2 (t), the voltage signal across the capacitor Vc(t) is A pulse signal is output by the signal output terminal.

[0024] Charging characteristic curve 1, given by the voltage Vc(t) across the capacitor during the charging phase 1 is an exponential increase function, and the formula of the charging characteristic curve 11 is Equation (1), and during the discharge phase The discharge characteristic curve 12 resulting from the voltage Vc(t) across the capacitor is exponential. It can be seen from FIG. 5 that the discharge characteristic curve 12 is a decreasing function and the formula is formula (2). do.

number

[0025] V0 is the final charge voltage or the initial discharge voltage, t1 is the charging time, and t2 is is the discharge time, R1 is the resistance of the charging resistor, and R2 is the resistance of the discharging resistor. and C is the capacitance value of the capacitor.

[0026] Therefore, the charging time t1 of the voltage Vc(t) across the capacitor during the charging phase is *Determined by the time constant of C, while the voltage across the capacitor during the discharge phase Vc(t) It can be seen that the discharge time t2 is determined by the time constant of R1*C.

[0027] V P is the peak voltage of the capacitor during the charging and discharging process, and V V Charging and The valley voltage of the capacitor during the discharge process, and the voltage across the discharge resistor during the charging phase, V R The current and voltage of 2(t) are both zero, and the voltage across the discharge resistor V R2 (t) is discharge It can be seen from FIG. 5 that the only one in the discharge phase is the Pressure V R2 The pulse period of (t) is T=t1+t2.

[0028] Referring to FIG. 6, FIG. 6 illustrates a magnetoresistive relaxation oscillator provided in accordance with one embodiment of the present disclosure. Schematic diagram of a magnetometer. The magnetoresistive relaxation oscillator magnetometer 1 is comprised of a capacitor 2 and a charging resistor 3. a discharge resistor 4; a charge / discharge switch 5; a high voltage power supply terminal 6; a ground terminal 7; and a signal output The charging resistor 3 includes at least one charging magnetoresistance unit. The discharge resistor 4 is composed of at least one discharge magnetoresistance unit. The first end is connected to a ground terminal 7. Optionally, the charge / discharge switch 5 has an on end 5a and A triode bidirectional switch including an off end 5b and a connection end 5c, and a high voltage source end 6 , is connected to the on-end 5a via a charging resistor 3, and the ground terminal 7 is connected to the on-end 5a via a discharging resistor 4. The first end of the capacitor 2 is connected to the off end 5b, and the second end of the capacitor 2 is connected to the connection end 5c. During the charging phase, the ON end 5a is connected to the connecting end 5c, and during the discharging phase, the OFF end 5b is connected It is electrically connected to the connecting end 5c.

[0029] Optionally, the charging resistor and the discharging resistor are opposite in the magnetic field sensing direction to provide a higher sensitivity. The resistance is the same when no external magnetic field is applied, and the resistance is the same when no external magnetic field is applied. forming a pull-type magnetoresistor. Optionally, the charging resistor is a magnetic field sensitive magnetoresistance unit.

[0030] In this embodiment, the capacitor 2 is connected between the connection end 5c of the charge / discharge switch 5 and the ground terminal 7. The charging resistor 3 is located between the high voltage source terminal 6 and the ON end 5a of the charging / discharging switch 5. The discharge resistor 4 is located between the ground terminal 7 and the off end 5b of the charge / discharge switch 5. As shown in FIG. 7, during the charging phase, the charge / discharge switch 5 is connected to the high voltage supply terminal 6. That is, the ON end 5a is connected to the connection end 5c of the charge / discharge switch 5, and the high The voltage source terminal (+Vdd) 6 is connected to a charging resistor in the path of the charging branch as shown by the arrow. During the discharge phase, the charge / discharge switch The off end 5b of the charge / discharge switch 5 is switched to the ground terminal 7. The capacitor 2 is connected to the connecting end 5c through the discharge branch path as shown by the arrow. Discharge is made to the ground terminal 7 via the discharge resistor 4 .

[0031] An external magnetic field is applied to the magnetometer 1 and during the charging phase, the external magnetic field induces a current in the charging resistor 3. During the discharge phase, the resistance change in the discharge resistor 4 due to the external magnetic field is During the charging phase, the signal output The terminal outputs a charging pulse voltage signal, and the charging pulse voltage signal is connected to one of the charging resistors or During the discharge phase, the signal output terminal outputs a discharge pulse voltage signal, The pulse voltage signal includes one or more harmonics of the discharge resistor. The signal processing circuit is The pulse signal at the signal output terminal is measured to measure the magnitude of the magnetic field.

[0032] FIG. 9 is a schematic graph of the voltage Vc(t) across the capacitor in the magnetometer 1. The voltage signal Vc(t) applied to the capacitor is a pulse signal output by the signal output terminal. be.

[0033] Charging characteristic curve 1, given by the voltage Vc(t) across the capacitor during the charging phase 1 is an exponentially increasing function that depends on the voltage across the capacitor Vc(t) during the discharge phase. It can be seen from FIG. 9 that the resulting charging characteristic curve 12 is an exponentially decreasing function. The charging time t1 of the voltage Vc(t) across the capacitor during the charging phase is the time constant R1*C On the other hand, the discharge time t2 of the voltage Vc(t) across the capacitor during the discharge phase is determined by is determined by the time constant R2*C.

[0034] Referring to FIG. 10, FIG. 10 illustrates a magnetoresistance relaxation generator provided in accordance with one embodiment of the present disclosure. FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer. The magnetoresistive relaxation oscillator magnetometer 1 comprises a capacitor 2 and a charging resistor a charge / discharge switch 5; a high voltage power supply terminal 6; a ground terminal 7; and a signal and an output terminal Vout. The charging resistor 3 is connected to at least one charging magnetoresistance unit. The discharge resistor 4 is composed of at least one discharge magnetoresistance unit. The first end of the charge / discharge switch 5 is connected to the ground terminal 7. a triode bidirectional switch including an off end 5b and a connection end 5c; a charging resistor and The first end of the capacitor 2 and the second end of the discharge resistor are the same common resistor 3&4. and common resistors 3 & 4 are connected in series to form an RC series, A high voltage source terminal 6 is connected to the ON end 5a, and a ground terminal 7 is connected to the OFF end 5b. During the charging phase, the ON end 5a is connected to the connection end 5c, and during the discharging phase, In the meantime, the off end 5b is electrically connected to the connection end 5c.

[0035] In this embodiment, a common resistor 3&4 is provided. The common resistor 3&4 is a charging resistor and and discharge resistors, and the common resistors 3 & 4 and the second end of the capacitor 2 are multiplexed as The RC series is electrically connected to the ground terminal 7 and the charge / discharge switch 11, during the charging phase, the charge / discharge switch 5c is located between the terminal 5c of the The switch 5 is switched to the high voltage source terminal 6, i.e., the ON end 5a is the charge / discharge switch 5, and a high voltage supply terminal (+Vdd) 6 is connected to the connection end 5c of the The capacitor 2 is charged through the common resistors 3 and 4 in the charging branch path. As shown, during the discharge phase, the charge / discharge switch 5 is switched to the ground terminal 7, i.e. The off end 5b is connected to the connection end 5c of the charge / discharge switch 5, and the capacitor 2 is connected to the The discharge is conducted to the ground terminal 7 via the common resistors 3 & 4 in the discharge branch path shown by the above. .

[0036] An external magnetic field is applied to magnetometer 1 and during the charging phase, the external magnetic field induces a current at common resistors 3&4. During the discharge phase, the external magnetic field causes a resistance change in the common resistors 3&4. During the charging phase, resistance changes are induced and therefore the charge and discharge times of the capacitor change. The signal output terminal outputs a charging pulse voltage signal, and the charging pulse voltage signal is connected to a common resistor 3& 4, and during the discharge phase, the signal output terminal is connected to a discharge pulse voltage signal , and the discharge pulse voltage signal includes one or more harmonics of the common resistors 3&4. The signal processing circuit measures the pulse signal at the signal output terminal in order to measure the magnitude of the external magnetic field. The number of resistors is reduced in this embodiment.

[0037] FIG. 13 is a circuit diagram of the equivalent trigger of FIG. 10. The magnetometer 1 further includes a low voltage supply terminal. The charge / discharge switch is a trigger, and the input and output terminals of the trigger are high A voltage source terminal or a low voltage source terminal, and the charging resistor and the discharging resistor are connected to the same common The second end of the capacitor is connected to the input terminal of the trigger. The two ends are connected to the trigger input and output terminals respectively, and the signal output terminal is The charge / discharge switch 5 is located at the output or input terminal of the trigger. and output terminal 8(2) as a high voltage power supply terminal and a low voltage power supply terminal, respectively. It is a Schmitt trigger (mit trigger). The capacitor 2 is connected between the ground terminal 7 and the input terminal 6 ( 2), and the two ends of the common resistor 3&4 are connected to the input terminal 6(2) of the trigger 5. and the output terminal 8(2).

[0038] During the charging phase, the output terminal 8(2) is the high voltage source terminal and the input terminal 6(2) is the low voltage The output terminal 8(2) charges the capacitor 2 through the common resistors 3 & 4. The voltage on the capacitor 2 increases. When the voltage on the capacitor 2 becomes higher than the threshold Vph, If the trigger 5 is not connected, the voltage is switched, i.e., the input terminal 6(2) is connected to the high voltage The output terminal 8(1) is a low voltage source terminal, and the output terminal 8(2) is a low voltage source terminal, which then enters the discharge phase. Enter.

[0039] During the discharge phase, capacitor 2 begins to discharge and the voltage at input terminal 6 (2) decreases. If the voltage across capacitor 2 is less than threshold Vp1, a voltage reversal occurs again at input terminal 6. (2) and output terminal 8(2), and capacitor 2 enters the charging process. The charging branch 9(2) and the discharging branch 10(2) are connected to the Schmitt trigger 5, and This is achieved by charging and discharging the capacitor 2.

[0040] Figure 14 shows the voltage Vc(t) and current of the capacitor at the output terminal of the trigger in Figure 10. 1 is a schematic graph of the voltage Vout(t). off The capacitor charging and discharging process is the peak voltage at the on is the charge and discharge process of the capacitor is the valley voltage, which is the charge provided by the voltage Vc(t) across the capacitor during the charging phase. The capacitance characteristic curve 11(2) is an exponentially increasing function, which indicates that the voltage across the capacitor during the discharge phase The charging characteristic curve 12(2) given by Vc(t) is an exponentially decreasing function. out(t) is the high and low level pulse voltage, the charging time is t1, and the discharging time is t2 and the charging time t1 is equal to the discharging time t2.

[0041] Referring to FIG. 15, FIG. 15 illustrates a magnetoresistance relaxation generator provided in accordance with one embodiment of the present disclosure. FIG. 1 is a schematic diagram of a magnetoresistive relaxation oscillator magnetometer. The magnetoresistive relaxation oscillator magnetometer 1 comprises a capacitor 2 and a charging resistor a charge / discharge switch 5; a high voltage power supply terminal 6; a ground terminal 7; and a signal and an output terminal Vout. The charging resistor 3 is connected to at least one charging magnetoresistance unit. The discharge resistor 4 is composed of at least one discharge magnetoresistance unit. The first end of the charge / discharge switch 5 is connected to the ground terminal 7. 5b and a connection end 5c. a is connected in series with diode 3b with the charging direction turned on to form the RD charging series. The discharge resistor 4a is connected to the RD discharge line in the discharge direction. RD charge series and RD discharge series are connected in series with the anode 4b to form the RD series. The second end of the capacitor 2 and the RD series are connected in parallel so as to form an RC series. The RC series is connected to the connection end 5c, and the high voltage power supply terminal 6 is connected to the on During the charging phase, the on-end 5a is connected to the on-end 5b, and the ground terminal 7 is connected to the off-end 5b. During the discharge phase, the off end 5b is connected to the connection end 5c. can be.

[0042] Optionally, the charging resistor and the discharging resistor are opposite in the magnetic field sensing direction to provide a higher sensitivity. The resistance is the same when no external magnetic field is applied, and the resistance is the same when no external magnetic field is applied. forming a pull-type magnetoresistor. Optionally, the charging resistor is a magnetic field sensitive magnetoresistance unit.

[0043] In this embodiment, the RC series is formed by connecting the capacitor 2 and the RD series in series. The RD series is formed by connecting the RD charge series and the RD discharge series in parallel. The RC series is formed by: As shown in FIG. 16, during the charging phase, the charge / discharge switch 5 is connected to the high voltage supply terminal 6. That is, the ON end 5a is switched to the connection end 5c of the charge / discharge switch 5. The high voltage supply terminal (+Vdd) 6 is connected to the RD series via the charging branch path as shown by the arrow. During the discharge phase, the charge / discharge switch The off end 5b of the charge / discharge switch 5 is switched to the ground terminal 7. The capacitor 2 is connected to the connecting end 5c through the discharge branch path as shown by the arrow. Discharge to ground terminal 7 via the RD series.

[0044] An external magnetic field is applied to the magnetometer 1 and during the charging phase, the external magnetic field changes the resistance in the RD series. During the discharge phase, the external magnetic field induces a resistance change in the RD series. During the charging phase, the signal output terminal Output a charging pulse voltage signal, and the charging pulse voltage signal is one or more harmonics of the RD series. During the discharge phase, the signal output terminal outputs a discharge pulse voltage signal, and the discharge pulse voltage The signal includes one or more harmonics of the RD sequence. The signal processing circuitry determines the magnitude of the external magnetic field. In order to measure the resistance, the pulse signal of the signal output terminal is measured. Decreases.

[0045] FIG. 18 is a circuit diagram of the equivalent trigger of FIG. 15. The magnetometer 1 further includes a low voltage supply terminal. The charge / discharge switch is a trigger, and the input and output terminals of the trigger are high A voltage source terminal or a low voltage source terminal, and a charging resistor is connected to the RD terminal to form a charging series. The discharge resistor is connected in series with a diode having a charging direction that is set to RD. A capacitor is connected in series with a diode having a discharge direction that is turned on to form a The second end of the resistor is connected to the input terminal of the trigger, and the RD charging series and the RD discharging series are The two ends of the parallel-connected RD charging series and RD discharging series are connected in parallel. The signal output terminal is connected to the trigger output terminal or the or the input terminal.

[0046] The charge / discharge switch 5 connects the input terminal 6(4) and the output terminal 8(4) to the high voltage source terminal. The Schmitt trigger has a low voltage supply terminal and a low voltage terminal. Capacitor 2 is connected to ground. The two ends of the RD series are connected between terminal 7 and input terminal 6 (4), and the two ends of the RD series are connected to the input of trigger 5. The charging branch 9(4) is connected between the terminal 6(4) and the output terminal 8(4), respectively. The discharge branch 10(4) includes a charging resistor 3a and a charging diode 3b connected in series. , a discharge resistor 4a and a discharge diode 4b connected in series, and a charging branch 9 (4) and the discharge branch 10(5) are connected in parallel.

[0047] During the charging phase, output terminal 8(4) is the high voltage source terminal and input terminal 6(4) is the low voltage The output terminal 8(4) charges the capacitor 2 through the charging resistor 3a. The voltage across capacitor 2 increases. When the voltage is higher than the threshold Vph, the trigger is activated. Voltage switching is performed, i.e., the input terminal 6(4) is a high voltage source terminal and the output terminal 8(4) is the low voltage supply terminal, which then enters the discharge phase.

[0048] During the discharge phase, the capacitor 2 starts to discharge through the discharge resistor 4a and the input terminal 6(4 ) decreases, and when the voltage is less than the threshold Vp1, a voltage reversal occurs at the input terminal 6( 4) and again at output terminal 8(4), and the charging process begins. Branch 9(4) and discharge branch 10(4) are connected to Schmitt trigger 5 and a capacitor This is carried out by charging and discharging the battery.

[0049] Figure 19 shows the voltage Vc(t) and current of the capacitor at the output terminal of the trigger in Figure 15. 1 is a schematic graph of the voltage Vout(t) across the capacitor during the charging phase. The charging characteristic curve 11(4) given by is an exponentially increasing function, during the discharge phase: The charging characteristic curve 12(4) caused by the voltage Vc(t) across the capacitor is Vout(t) is the high and low level pulse voltage, and the charging time is t 1 and the discharge time is t2.

[0050] The charge and discharge function of the RC series is given by the formula of its frequency f, the charge time t1 and the discharge time t2. The charging time t2 is as follows: f=0.8 / (RC) t1 ∝ R1C t2 ∝ R2C It is.

[0051] The charging time t1 is directly proportional to the charging resistor R1, and the discharging time t2 is directly proportional to the discharging resistor R2. It is understandable to give examples.

[0052] The above solution includes the following three cases:

[0053] In case 1, t1=t2, i.e., R and C form a series combination, and then , charging and discharging are performed, and the charging resistor R1 and the discharging resistor R2 are the same or the same 1 There are two common resistors.

[0054] In case 2, t1 varies and t2 is constant, i.e., the discharge resistor R2 does not change. The magnetic shielding magnetoresistive unit remains the same, i.e., only the charging resistor R1 is external. R2 and R1 constitute the sensing reference magnetoresistor pair. do.

[0055] In case 3, t1+t2=constant, i.e., the charging branch R1 and the discharging branch R2 are A push-pull type magnetoresistor pair.

[0056] The output pulse function of the signal output terminal is a piecewise periodic function with a period T=t1+t2 and a base The basic formula is,

number

number

number

number

number

[0057] For magnetometer 1, which contains a single resistor R, t1 = t2, t1 + t2 = T = 2t1, and Therefore, a signal processing circuit may be employed as shown in FIG. The output terminal of the Schmitt trigger in 2) is connected directly to the frequency f / voltage V converter 21 or to an external Then, it is connected to the V-1 / V converter 22, and finally, the output voltage is The voltage during the charging / discharging time period T is directly proportional to the field H. , connected to an FV converter, which converts the pulse signal into a voltage signal, and then The voltage signal is converted by a V-1 / V converter into a voltage signal that is directly proportional to the external magnetic field.

[0058] As shown in FIG. 21, the signal output terminal Vout is connected to an RC low-pass filter 2 2, a first end of a first capacitor 24 in an RC low-pass filter 25 is connected is connected to the ground terminal, and the first resistor 23 in the RC low-pass filter 25 A first capacitor is disposed between the signal output terminal Vout and the second end of the first capacitor. The two ends of the sensor 24 output DC and the first harmonic, and the signal processing circuit outputs and converting the signal across the first capacitor 24 to obtain a discharge period value.

[0059] As mentioned above, the Schmitt trigger output of relaxation oscillator 1 (4) is a single R A Clpf capacitor 24 is connected to the lpf resistor 23 and ground. The Rlpf resistor 23 and the Clpf resistor 24 are connected between the The low-pass filter 25 forms a periphery of the amplifier and then outputs the signal to Vout. It can be seen that by removing some of the wave numbers, the formula V0 can be obtained directly. In an oscillatory circuit of a push-pull coupled magnetoresistor pair, t1+t2=constant, and as t1 increases The increase in t2 is directly proportional to R, and the decrease in t2 is directly proportional to R. Therefore, V0 is directly proportional to the external magnetic field H. For example:

[0060] Another way is to use a harmonics converter where two or more harmonics are in the range of V0+V 1(t) To obtain the low pass filter Therefore, the value of t1+t2 is V1(t ), and (t1+t2)*V0 is H is directly proportional to.

[0061] Optionally, the signal output terminal of the magnetoresistive relaxation oscillator magnetometer may be an analog The pulse signal is converted into a digital signal by the analog-to-digital converter 31. The converted signal is then processed and The signal processing circuit outputs the signal to the microprocessor to obtain the charging and discharging periods. Optionally, an analog-to-digital converter 31 measures the signal output directly. The analog signal may be converted to a digital signal, and the microprocessor 32 may include a DSP or It is an MCU that directly outputs a digital signal related to the external magnetic field H through a certain algorithm. The trigger output terminal of the relaxation oscillator 1 (2) is connected to an AD converter 31, and The signal is converted into a digital signal, and then the digital signal is input to the MCU / DSP32 and The rising or falling edge times are counted directly, and the time A value is output, which is directly proportional to H.

[0062] For any of the above embodiments, FIG. 23 shows four typical signal outputs of a relaxation oscillator magnetometer. The corresponding charging and discharging resistors in figure (a) are common resistors. When the charge time t1 is equal to the discharge time t2, the value of H is then similarly can be obtained by measuring the corresponding charging resistor and discharge resistor in figure (b). When the resistor is a common resistor, the period T=t1+t2 or the pulse frequency f is measured directly. and 1 / f is calculated, then the value of H can be measured. Figure (c) shows the push-pull type magnetoresistor pair, t1+t2=constant, and (t1-t2) / (t1+t2) is , which is directly proportional to the external magnetic field H. Figure (d) shows a pair of sensing reference magnetoresistors, with t2 = constant. and t1 / t2 is directly proportional to the external magnetic field H.

[0063] The above are merely preferred embodiments and applied technical principles of the present disclosure. It should be noted that the present disclosure is not limited to the specific embodiments described herein. Various obvious modifications, rearrangements, combinations and substitutions may be made without departing from the scope of protection of the Those skilled in the art will understand that such conversions may be made by those skilled in the art. The disclosure has been described in more detail by the above embodiments, but the present disclosure is not limited to the above embodiments. The present disclosure is not limited to the above embodiments, and includes many equivalent embodiments without departing from the concept of the present disclosure. The scope of the present disclosure is determined by the appended claims.

Claims

1. A magnetoresistive relaxation oscillator magnetometer comprising: a capacitor; a charging resistor; a discharging resistor; a charging / discharging switch; a high voltage source terminal; a ground terminal; and a signal output terminal, the charging resistor being comprised of at least one charging magnetoresistance unit, and the discharging resistor being comprised of at least one discharging magnetoresistance unit, a first end of the capacitor is connected to the ground terminal, and a second end of the capacitor is configured to be switched by the charge / discharge switch to connect to the charging resistor during a charging phase and to connect to the discharging resistor during a discharging phase; During a charging phase, the high voltage source terminal charges the capacitor through the charging resistor, by switching the charge / discharge switch, while during a discharging phase, the capacitor discharges through the discharging resistor to the ground terminal, by switching the charge / discharge switch; When an external magnetic field causes a resistance change in the charging resistor and the discharging resistor, the charging and discharging time of the capacitor changes, and a pulse signal output by the signal output terminal includes one or more harmonics of the charging resistor or the discharging resistor, and a signal processing circuit measures the pulse signal to measure the external magnetic field.

2. The magnetoresistive relaxation oscillator magnetometer of claim 1 , wherein the charge magnetoresistive unit and the discharge magnetoresistive unit are anisotropic magnetoresistive units, giant magnetoresistive units, or tunneling magnetoresistive units.

3. the charge / discharge switch is a metal oxide semiconductor field effect transistor (MOSFET), the second end of the capacitor and the second end of the charging resistor are both connected to a gate of the MOSFET, the discharge resistor is located between a drain of the MOSFET and the ground terminal, and the high voltage supply terminal is connected to a first end of the charging resistor and a source of the MOSFET, respectively; or 2. The magnetoresistive relaxation oscillator magnetometer of claim 1, wherein the charge / discharge switch is a triode, the second end of the capacitor and the second end of the charging resistor are both connected to the base of the triode, the discharge resistor is located between the emitter of the triode and the ground terminal, and the high voltage source terminal is connected to the first end of the charging resistor and to the collector of the triode, respectively.

4. The charge / discharge switch is a triode bidirectional switch having an on end, an off end, and a connection end, a high voltage source end is connected to the on end through the charge resistor, the ground terminal is connected to the off end through the discharge resistor, and the second end of the capacitor is connected to the connection end; 2. The magnetoresistive relaxation oscillator magnetometer of claim 1, wherein during a charging phase, the ON end is conducted to the connecting end, and during a discharging phase, the OFF end is conducted to the connecting end.

5. the charge / discharge switch is a triode bidirectional switch having an on end, an off end, and a connection end, the charge resistor is connected in series with a diode having a charge direction turned on to form an RD charge series, the discharge resistor is connected in series with a diode having a discharge direction turned on to form an RD discharge series, the RD charge series and the RD discharge series are connected in parallel to form an RD series, the second end of the capacitor and the RD series are connected in series to form an RC series, the RC series is connected with the connection end, the high voltage source terminal is connected with the on end, and the ground terminal is connected with the off end; 2. The magnetoresistive relaxation oscillator magnetometer of claim 1, wherein during a charging phase, the ON end is conducted to the connecting end, and during a discharging phase, the OFF end is conducted to the connecting end.

6. Further comprising a low voltage power supply terminal; 2. The magnetoresistive relaxation oscillator magnetometer of claim 1, wherein the charge / discharge switch is a trigger, an input terminal and an output terminal of the trigger are the high voltage supply terminal or the low voltage supply terminal, respectively, the charge resistor is connected in series with a diode having a charge direction that is turned on to form an RD charging series, the discharge resistor is connected in series with a diode having a discharge direction that is turned on to form an RD discharging series, the second end of the capacitor is connected to the input terminal of the trigger, the RD charging series and the RD discharging series are connected in parallel, two ends of the parallel connected RD charging series and the RD discharging series are connected to the input terminal and the output terminal of the trigger, respectively, and the signal output terminal is located at the output terminal or the input terminal of the trigger.

7. 7. The magnetoresistive relaxation oscillator magnetometer of claim 3, wherein the charging resistor and the discharging resistor are opposite in magnetic field sensing direction, identical in sensitivity, and identical in resistance when no external magnetic field is applied, forming a push-pull type magnetoresistor.

8. The magnetoresistive relaxation oscillator magnetometer of any one of claims 3 to 6, wherein the charging resistor is a magnetic field sensitive magnetoresistive unit.

9. 2. The magnetoresistive relaxation oscillator magnetometer of claim 1, wherein the signal output terminal is connected to an RC low pass filter, a first end of a first capacitor in the RC low pass filter is connected to the ground terminal, a first resistor in the RC low pass filter is located between the signal output terminal and a second end of the first capacitor, the two ends of the first capacitor output DC and a first harmonic, and the signal processing circuit converts the signal across the first capacitor to obtain a charge period value and a discharge period value.

10. 2. The magnetoresistive relaxation oscillator magnetometer of claim 1, wherein the signal output terminal is connected to an analog-to-digital converter, the pulse signal is converted by the analog-to-digital converter, and then the converted signal is processed and output by a microprocessor, and the signal processing circuit directly measures the signal output by the microprocessor to obtain the charging period and the discharging period.

11. A magnetoresistive relaxation oscillator magnetometer comprising a capacitor, a charging resistor, a discharging resistor, a charging / discharging switch, a high voltage source terminal, a ground terminal, and a signal output terminal, the charging resistor and the discharging resistor being configured as a common resistor, the common resistor being configured as a magnetoresistive unit, a first end of the capacitor is connected to the ground terminal, a second end of the capacitor is switched by the charge / discharge switch, and the common resistor functions as the charge resistor or the discharge resistor; During a charging phase, the high voltage source terminal charges the capacitor through the common resistor by switching the charge / discharge switch, while during a discharging phase, the capacitor discharges through the common resistor to the ground terminal by switching the charge / discharge switch; When an external magnetic field causes a resistance change in the common resistor, the charging and discharging time of the capacitor changes, and a pulse signal output by the signal output terminal contains one or more harmonics of the common resistor, and a signal processing circuit measures the pulse signal to measure the external magnetic field.

12. The charge / discharge switch is a triode bidirectional switch having an on end, an off end, and a connection end, the second end of the capacitor and the common resistor are connected in series to form an RC series, the RC series is connected to the connection end, the high voltage source terminal is connected to the on end, and the ground terminal is connected to the off end; During a charging phase, the on-end is connected to the connection end, and the common resistor functions as the charging resistor; 12. The magnetoresistive relaxation oscillator magnetometer of claim 11, wherein during a discharging phase, the off end is conducted to the connected end and the common resistor functions as the discharging resistor.

13. Further comprising a low voltage power supply terminal; the charge / discharge switch is a trigger, the input terminal and the output terminal of the trigger are the high voltage source terminal or the low voltage source terminal, respectively; during a charging phase, the common resistor functions as the charge resistor, and during a discharging phase, the common resistor functions as the discharge resistor; 12. The magnetoresistive relaxation oscillator magnetometer of claim 11, wherein the second end of the capacitor is connected to the input terminal of the trigger, the two ends of the common resistor are connected to the input terminal and the output terminal of the trigger, respectively, and the signal output terminal is located at the output terminal or the input terminal of the trigger.

14. The magnetoresistive relaxation oscillator magnetometer of claim 12 or 13, wherein the signal output terminal is connected to an FV converter, which converts the pulse signal into a voltage signal, which is then converted by a V-1 / V converter into a voltage signal directly proportional to the external magnetic field.

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