Magnetoresistive element and sensing device

Abstract

The invention discloses a magnetoresistive element and sensing equipment, and relates to the technical field of magnetic field measurement. The magnetoresistive element comprises at least one magnetoresistive sub-element, the magnetoresistive sub-element comprises a plurality of bridge arms, and the bridge arms are mutually coupled to form a Wheatstone bridge structure; at least one bridge arm comprises a magnetic resistance bridge arm and a compensation resistor, and the compensation resistor is coupled with the magnetic resistance bridge arm in parallel and used for enabling the resistance of the bridge arm to be lower than that of the magnetic resistance bridge arm; the magnetic resistance bridge arm comprises at least one magnetic tunnel junction, each magnetic tunnel junction has the same magnetic sensitive axis, and the magnetic sensitive axis is parallel or perpendicular to the free layer plane. The bandwidth of the magnetoresistive element is expanded by adjusting the resistance of the bridge arms in the magnetoresistive element, so that the magnetoresistive element can be further used for measuring electrical variables such as high-frequency current, and the magnetoresistive element has the advantages of being simple in structure and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field detection technology, and in particular to a magnetoresistive element and a sensing device. Background Art

[0002] A current sensor is a device for detecting current. It is generally used in actual current measurement and protection systems, such as photovoltaics, wind power, electricity, smart grids, railway electromechanical, aerospace, new energy vehicles and other fields. As the main detection element, the current sensor plays a vital role in ensuring the safety and stability of the system.

[0003] In GaN-based power converter systems, partial discharge of traditional power equipment and other scenarios, it is often necessary to detect current signals at the DC to tens of MHz level.

[0004] The working bandwidth of current sensors based on magnetoresistance effect is generally lower than 1MHz, and it is difficult to detect load currents above 1MHz. At present, the bandwidth is generally improved by combining TMR magnetoresistance elements with other sensing principle elements, such as combining TMR with Rogowski coils or mutual inductors. However, this method generally has problems such as complex back-end signal processing circuits, increased power consumption, and complex micro-nano integration processes. Summary of the invention

[0005] The main purpose of the present invention is to provide a magnetoresistive element and a sensing device, aiming to solve the technical problem that existing magnetoresistive elements are difficult to apply to magnetic field measurement above 1 MHz.

[0006] To achieve the above object, a first aspect of the present invention provides a magnetoresistive element, the magnetoresistive element comprising at least one magnetoresistive sub-element;

[0007] The magnetic resistance sub-element comprises a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm coupled to each other, and has a Wheatstone bridge structure; when there is a zero magnetic field, the resistances of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are the same;

[0008] At least one of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm comprises a magnetoresistive bridge arm and a compensation resistor, wherein the compensation resistor is coupled in parallel with the magnetoresistive bridge arm and is used to make the resistance of the bridge arm lower than the resistance of the magnetoresistive bridge arm;

[0009] The magnetoresistive bridge arm includes at least one magnetic tunnel junction, each of the magnetic tunnel junctions has the same magnetic sensitive axis, and the magnetic sensitive axis is parallel or perpendicular to the free layer plane.

[0010] According to some embodiments of the present invention, the first bridge arm includes a first magnetoresistance bridge arm and a first compensation resistor, the second bridge arm includes a second magnetoresistance bridge arm and a second compensation resistor, the third bridge arm includes a third magnetoresistance bridge arm and a third compensation resistor, and the fourth bridge arm includes a fourth magnetoresistance bridge arm and a fourth compensation resistor;

[0011] Under an external magnetic field within a preset range, the resistances of the first compensation resistor, the second compensation resistor, the third compensation resistor and the fourth compensation resistor remain unchanged;

[0012] Under the external magnetic field within the preset range, the first magnetoresistance bridge arm and the third magnetoresistance bridge arm have a first resistance change value, and the second magnetoresistance bridge arm and the fourth magnetoresistance bridge arm have a second resistance change value different from the first resistance change value.

[0013] According to some embodiments of the present invention, the first compensation resistor, the second compensation resistor, the third compensation resistor and the fourth compensation resistor have the same resistance;

[0014] When there is a zero magnetic field, the resistances of the first magnetoresistance bridge arm, the second magnetoresistance bridge arm, the third magnetoresistance bridge arm and the fourth magnetoresistance bridge arm are the same;

[0015] The first resistance change value is opposite to the second resistance change value.

[0016] According to some embodiments of the present invention, the bandwidth of the magnetoresistive sub-element is related to the bandwidth of the magnetoresistive bridge arm, the resistance value of the magnetoresistive bridge arm in zero magnetic field, and the resistance value of the compensation resistor;

[0017] The greater the ratio of the resistance value of the magnetoresistive bridge arm under zero magnetic field to the resistance value of the compensation resistor, the greater the bandwidth of the magnetoresistive sub-element.

[0018] According to some embodiments of the present invention, under the external magnetic field within the preset range, the ratio of the sensitivity of the magnetoresistive element to the sensitivity of the magnetoresistive bridge arm is

[0019] Wherein, r is the resistance value of the compensation resistor; R1 is the resistance value of the magnetoresistive bridge arm in zero magnetic field.

[0020] According to some embodiments of the present invention, the first bridge arm includes a first magnetoresistance bridge arm and a first compensation resistor, the second bridge arm includes only a second magnetoresistance bridge arm, the third bridge arm includes a third magnetoresistance bridge arm and a third compensation resistor, and the fourth bridge arm includes only a fourth magnetoresistance bridge arm;

[0021] Under zero magnetic field, the resistance value of the first bridge arm after the first magnetoresistance bridge arm is coupled in parallel with the first compensation resistor and the resistance value of the third bridge arm after the third magnetoresistance bridge arm is coupled in parallel with the third compensation resistor are equal to the resistance value of the second magnetoresistance bridge arm or the fourth magnetoresistance bridge arm;

[0022] Under an external magnetic field within a preset range, the resistance value of the first compensation resistor is the same as the resistance value of the second compensation resistor.

[0023] According to some embodiments of the present invention, the compensation resistor comprises:

[0024] A compensating magnetoresistance, comprising at least one magnetic tunnel junction; the compensating magnetoresistance has a first resistance in a zero magnetic field;

[0025] A shielding member covers the surface of the compensating magnetic resistor and is used to keep the resistance of the compensating magnetic resistor at the first resistance under a magnetic field within a preset range.

[0026] According to some embodiments of the present invention, the magnetic tunnel junction includes a top electrode layer, a pinning layer, a pinned layer, a tunneling layer, a free layer and a bottom electrode layer; the free layer is close to the top electrode layer or the bottom electrode layer, the tunneling layer is close to the free layer, the pinned layer is close to the tunneling layer, and the pinning layer is close to the pinned layer;

[0027] The at least one magnetic tunnel junction is electrically coupled to each other through the top electrode layer and / or the bottom electrode layer;

[0028] The magnetoresistive bridge arm is electrically coupled to the compensation resistor through the top electrode layer and the bottom electrode layer.

[0029] According to some embodiments of the present invention, the bandwidth of the magnetoresistive element is higher than 1 MHz.

[0030] To achieve the above objective, a second aspect of the present invention provides a sensing device, the sensing device comprising a magnetoresistive element; the magnetoresistive element is the magnetoresistive element described above.

[0031] Therefore, compared with the prior art, the present invention has the following beneficial effects:

[0032] The magnetoresistive element disclosed in the present invention includes at least one magnetoresistive element, which includes a plurality of bridge arms, each bridge arm is coupled to each other to form a Wheatstone bridge structure; at least one bridge arm includes a magnetoresistive bridge arm and a compensation resistor, the compensation resistor is coupled in parallel with the magnetoresistive bridge arm, and is used to make the resistance of the bridge arm lower than the resistance of the magnetoresistive bridge arm; the magnetoresistive bridge arm includes at least one magnetic tunnel junction, each magnetic tunnel junction has the same magnetic sensitive axis, and the magnetic sensitive axis is parallel or perpendicular to the free layer plane. The present invention expands the bandwidth of the magnetoresistive element by adjusting the bridge arm resistance in the magnetoresistive element, so that the magnetoresistive element can be further used for measuring electrical variables such as high-frequency current, and has the beneficial effects of simple structure and easy implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of a high-frequency impedance model of a magnetoresistive element of an existing Wheatstone bridge structure;

[0035] Figure 2 A schematic diagram of the structure of a magnetoresistive element according to an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of a high-frequency impedance model of a magnetoresistive element according to an embodiment of the present invention;

[0037] Figure 4 A curve showing a gain variation with frequency of a magnetoresistive element according to an embodiment of the present invention;

[0038] Figure 5 A schematic structural diagram of a magnetoresistive element according to another embodiment of the present invention;

[0039] Figure 6 FIG. 4 is a schematic structural diagram of a magnetoresistive element according to another embodiment of the present invention.

[0040] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0043] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0044] A current sensor is a device for detecting current. It is generally used in actual current measurement and protection systems, such as photovoltaics, wind power, electricity, smart grids, railway electromechanical, aerospace, new energy vehicles and other fields. As the main detection element, the current sensor plays a vital role in ensuring the safety and stability of the system.

[0045] In scenarios such as GaN-based power converter systems and partial discharge of traditional power equipment, it is often necessary to detect current signals at the DC to MHz level.

[0046] The working bandwidth of current sensors based on tunneling magnetoresistance effect is generally lower than 1MHz, and it is difficult to detect load currents above 1MHz. At present, the bandwidth is generally improved by combining TMR magnetoresistance elements with elements based on other sensing principles, such as combining TMR with Rogowski coils or mutual inductors. However, this method generally has problems such as complex back-end signal processing circuits, increased power consumption, and complex micro-nano integration processes.

[0047] Therefore, it is necessary to develop a magnetoresistive element with a higher operating bandwidth.

[0048] The embodiment of the present invention provides a magnetoresistive element, aiming to solve the technical problem that the existing magnetoresistive element is difficult to apply to the magnetic field measurement above 1 MHz.

[0049] The magnetoresistive element of the embodiment of the present invention includes at least one magnetoresistive sub-element, and the magnetoresistive sub-element includes a plurality of bridge arms, and each bridge arm is coupled to each other to form a Wheatstone bridge structure. Among the plurality of bridge arms, at least one bridge arm includes a magnetoresistive bridge arm and a compensation resistor, and the compensation resistor is coupled in parallel with the magnetoresistive bridge arm to make the resistance of the bridge arm lower than the resistance of the magnetoresistive bridge arm; the magnetoresistive bridge arm includes at least one magnetic tunnel junction, and each magnetic tunnel junction has the same magnetic sensitive axis, and the magnetic sensitive axis is perpendicular or parallel to the free layer plane.

[0050] The magnetoresistive bridge arm can sense the external magnetic field under a preset range of external magnetic field, so that the resistance outputted by it is related to the magnitude of the external magnetic field. Each magnetic tunnel junction includes at least a free layer, which can have a variable magnetization direction under a preset range of external magnetic field; the plane parallel to the free layer is the free layer plane.

[0051] In one embodiment of the present invention, the structure of the magnetoresistive element is as follows: Figure 2 As shown, the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are coupled to each other, and the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm have the same resistance value under zero magnetic field. The magnetoresistive bridge arms in adjacent bridge arms have different reference magnetization directions.

[0052] Specifically, the first bridge arm is composed of the first magnetoresistance bridge arm R1 and the first compensation resistor r1 in parallel; the second bridge arm is composed of the second magnetoresistance bridge arm R2 and the second compensation resistor r2 in parallel; the third bridge arm is composed of the third magnetoresistance bridge arm R3 and the third compensation resistor r3 in parallel; the fourth bridge arm is composed of the fourth magnetoresistance bridge arm R4 and the fourth compensation resistor r4 in parallel.

[0053] In the embodiment of the present invention, each bridge arm in the Wheatstone bridge is designed to be a parallel structure of a magnetoresistive bridge arm and a compensation resistor, so that the resistance of each bridge arm itself is lower than the resistance of each magnetoresistive bridge arm.

[0054] The embodiment of the present invention improves the bandwidth of the magnetoresistive element by reducing the resistance value of each bridge arm.

[0055] The TMR magnetoresistive elements used for measurement are generally connected together through tunnel magnetoresistive units to form a Wheatstone full-bridge structure. The high-frequency equivalent impedance model of the existing Wheatstone structure magnetoresistive element is as follows: Figure 1As shown. The resistance value of the first magnetoresistive bridge arm R1 is the same as the resistance value of the third magnetoresistive bridge arm R3, and the resistance value of the second magnetoresistive bridge arm R2 is the same as the resistance value of the fourth magnetoresistive bridge arm R4; there are parasitic capacitances C1, C2, C3, C4, C5, and C6 between each end point, which change slightly under a MHz-level magnetic field and can be considered as a constant. The equivalent cutoff frequency of the magnetoresistive element is Where T is the time constant, which is determined by the port equivalent resistance and capacitance, and the time constant Where R1 is the resistance value of the first magnetoresistive bridge arm R1 at zero magnetic field, R2 is the resistance value of the second magnetoresistive bridge arm R2 at zero magnetic field, C1 is the capacitance value of the parasitic capacitor C1, C2 is the capacitance value of the parasitic capacitor C2, and C6 is the capacitance value of the parasitic capacitor C6. Since R1=R2, Therefore, the equivalent cutoff frequency, ie, the bandwidth, of the magnetoresistive element can be increased by reducing the resistance value of each bridge arm, and the equivalent cutoff frequency can even be increased to the MHz range.

[0056] In one embodiment of the present invention, a high frequency equivalent impedance model schematic diagram of a magnetoresistive element is shown in FIG. Figure 3 The resistance value R'1 of the first bridge arm is the parallel resistance value of the first magnetoresistive bridge arm R1 and the first compensation resistor r1, which conforms to: And R'1<R1, R1 is the resistance value of the first magnetoresistive bridge arm under zero magnetic field, r1 is the resistance value of the first compensation resistor; the resistance value R'2 of the second bridge arm is the parallel resistance value of the second magnetoresistive bridge arm R2 and the second compensation resistor r2, which meets: And R'2<R2, R2 is the resistance value of the second magnetoresistive bridge arm R2 under zero magnetic field, r2 is the resistance value of the second compensation resistor r2; the resistance value R'3 of the third bridge arm is the parallel resistance value of the third magnetoresistive bridge arm R3 and the third compensation resistor r3, which meets: And R'3<R3, R3 is the resistance value of the third magnetoresistive bridge arm R3 under zero magnetic field, r3 is the resistance value of the third compensation resistor r3; the resistance value R'4 of the fourth bridge arm is the parallel resistance value of the fourth magnetoresistive bridge arm R4 and the fourth compensation resistor r4, which meets: And R'4<R4, R4 is the resistance value of the fourth magnetoresistive bridge arm R4 under zero magnetic field, r4 is the resistance value of the fourth compensation resistor r4; parasitic capacitances C1, C2, C3, C4, C5, C6 exist between each end point.

[0057] When the external magnetic field is zero, the resistance values ​​of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm in the magnetoresistive element of the embodiment of the present invention are all the same, which meets the following requirements: Therefore, the equivalent cutoff frequency f' of the magnetoresistive element is u conform to:

[0058]

[0059] Therefore, the bandwidth of the magnetoresistive element of the embodiment of the present invention is higher than the bandwidth of the magnetoresistive element including only the magnetoresistive bridge arm, and its bandwidth is related to the bandwidth of the magnetoresistive bridge arm and the resistance value of the magnetoresistive bridge arm under zero magnetic field, that is, the resistance value of the compensation resistor. The greater the ratio of the resistance value of the magnetoresistive bridge arm under zero magnetic field to the resistance value of the compensation resistor, the greater the bandwidth of the magnetoresistive element.

[0060] When the resistance value of the magnetoresistive bridge arm is constant under zero magnetic field, the smaller the resistance value of the compensation resistor is, the larger the bandwidth of the magnetoresistive sub-element is. However, as the resistance value of the compensation resistor is smaller, the sensitivity of the magnetoresistive sub-element is also reduced to a certain extent.

[0061] Specifically, when the resistance value of the first magnetoresistive bridge arm R1 increases by the first resistance change value ΔR1 from R1, the resistance value of the second magnetoresistive bridge arm R2 decreases by the first resistance change value ΔR1.

[0062] The resistance value of the first bridge arm R'1+ΔR'1 meets the following requirements:

[0063] The resistance value of the second bridge arm R'2-ΔR'2 meets the following conditions:

[0064] The sensitivity S of the magnetoresistive element complies with:

[0065]

[0066] Among them, V out (ΔR1) is the differential output signal of the magnetoresistive element; V in (ΔR1) Input signal of the magnetoresistive element;

[0067] Therefore, the sensitivity of the magnetoresistive element of the embodiment of the present invention is lower than the sensitivity of the magnetoresistive element including only the magnetoresistive bridge arm, and its sensitivity is twice the sensitivity of the magnetoresistive bridge arm. times.

[0068] Since the first resistance change value ΔR1 is small, The value of can generally be ignored, that is, under the external magnetic field within the preset range, the ratio of the sensitivity of the magnetoresistive element to the sensitivity of the magnetoresistive bridge arm can be expressed as

[0069] To verify the bandwidth improvement effect of the magnetoresistive element of the embodiment of the present invention, the inventors applied magnetic fields of different frequencies around the magnetoresistive element of the embodiment of the present invention and tested the ratio of the output value to the input value of the magnetoresistive element at different frequencies, i.e., the gain.

[0070] The gain of the magnetoresistive element including only one magnetoresistive element at different frequencies in the embodiment of the present invention is as follows: Figure 4 As shown. Figure 4Before the compensation resistor is used as the parallel resistor of the magnetoresistive bridge arm, the -3dB cutoff frequency of the magnetoresistive element is 0.75MHz; after the compensation resistor is used as the parallel resistor of the magnetoresistive bridge arm, the -3dB cutoff frequency of the magnetoresistive element is increased to 1.29MHz. This shows that the setting of the compensation resistor is helpful to increase the -3dB cutoff frequency of the magnetoresistive element, that is, to increase the bandwidth of the magnetoresistive element.

[0071] Therefore, the magnetoresistive element disclosed in the embodiment of the present invention expands the bandwidth of the magnetoresistive element by adjusting the bridge arm resistance in the magnetoresistive element, so that the magnetoresistive element can be further used to measure electrical variables such as high-frequency current, and has the beneficial effects of simple structure and easy implementation.

[0072] It should be understood that the first compensation resistor, the second compensation resistor, the third compensation resistor and the fourth compensation resistor in the present embodiment have fixed resistances, and their resistance values ​​are not affected by the magnetic field within a certain external magnetic field range, that is, the resistance values ​​remain unchanged. The first magnetoresistance bridge arm, the second magnetoresistance bridge arm, the third magnetoresistance bridge arm and the fourth magnetoresistance bridge arm have certain resistance change values ​​under an external magnetic field within a preset range, wherein the first magnetoresistance bridge arm and the second magnetoresistance bridge arm have a first resistance change value, and the third magnetoresistance bridge arm and the fourth magnetoresistance bridge arm have a second resistance change value, and the first resistance change value is different from the second resistance change value.

[0073] In this embodiment, the resistance values ​​of the first compensation resistor, the second compensation resistor, the third compensation resistor and the fourth compensation resistor are the same; in zero magnetic field, the resistance values ​​of the first magnetoresistance bridge arm, the second magnetoresistance bridge arm, the third magnetoresistance bridge arm and the fourth magnetoresistance bridge arm are the same; at the same time, the change value of the first resistance is opposite to the change value of the second resistance.

[0074] It should be understood that each bridge arm in the magnetoresistive element of the embodiment of the present invention includes a magnetoresistive bridge arm and a compensation resistor. Under zero magnetic field, the resistance value of each bridge arm is the same, the resistance value of the compensation resistors relative to the bridge arm is the same, and the resistance value of the compensation resistors of adjacent bridge arms is different.

[0075] It should be noted that, in the embodiment of the present invention, each bridge arm in the magnetoresistive sub-element may also be partially a parallel structure having a magnetoresistive bridge arm and a compensation resistor, and partially only having a magnetoresistive bridge arm.

[0076] In another embodiment of the present invention, Figure 5As shown, the magnetoresistive sub-element includes a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm coupled in sequence, and under a zero magnetic field, the resistance value of each bridge arm is the same, wherein the first bridge arm includes a first magnetoresistive bridge arm and a first compensation resistor, and the resistance value of the first compensation resistor is greater than zero, that is, the resistance value of the first bridge arm is equal to the resistance value of the first magnetoresistive bridge arm; the second bridge arm only includes the second magnetoresistive bridge arm, and the resistance value of the second bridge arm is equal to the resistance value of the second magnetoresistive bridge arm; the third bridge arm includes a third magnetoresistive bridge arm and a third compensation resistor, and the resistance value of the third compensation resistor is the same as the resistance value of the first compensation resistor: the fourth bridge arm only includes a fourth magnetoresistive bridge arm and a fourth compensation resistor, and the resistance value of the fourth bridge arm is equal to the resistance value of the second magnetoresistive bridge arm.

[0077] In yet another embodiment of the present invention, Figure 6 As shown, the magnetoresistive sub-element includes a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm coupled in sequence, and under a zero magnetic field, the resistance value of each bridge arm is the same, wherein the first bridge arm includes a first magnetoresistive bridge arm and a first compensation resistor, and the resistance value of the first compensation resistor is greater than zero, that is, the resistance value of the first bridge arm is equal to the resistance value of the first magnetoresistive bridge arm; the second bridge arm only includes the second magnetoresistive bridge arm, and the resistance value of the second bridge arm is equal to the resistance value of the second magnetoresistive bridge arm; the third bridge arm only includes the third magnetoresistive bridge arm, and the resistance value of the third bridge arm is equal to the resistance value of the third magnetoresistive bridge arm; the fourth bridge arm only includes the fourth magnetoresistive bridge arm, and the resistance value of the fourth bridge arm is equal to the resistance value of the fourth magnetoresistive bridge arm.

[0078] The compensation resistor of the embodiment of the present invention can be a fixed resistor, or it can be composed of a compensation magnetic resistor and a shielding member. The compensation magnetic resistor includes at least one magnetic tunnel junction, and the compensation magnetic resistor has a first resistance under zero magnetic field; the shielding member is covered on the surface of the compensation magnetic resistor to keep the resistance value of the compensation magnetic resistor unchanged under a magnetic field within a preset range.

[0079] It should be understood that when the magnetoresistive element is used for magnetic field measurement, the resistance value of the compensation magnetoresistive element remains unchanged under an external magnetic field within a preset range. The shielding member can be made of a soft magnetic material such as NiFe, which covers and shields the magnetic field around the compensation magnetoresistive element, thereby preventing the resistance value of the compensation magnetoresistive element from being affected by the external magnetic field and maintaining the resistance value at zero magnetic field. The soft magnetic material is not limited to NiFe and is not specifically limited here.

[0080] The structure of the magnetic tunnel junction in the magnetoresistive bridge arm and the magnetic tunnel junction in the compensation magnetoresistive of the embodiment of the present invention may include a top electrode layer, a pinning layer, a pinned layer, a tunneling layer, a free layer and a bottom electrode layer stacked in sequence, or include a bottom electrode layer, a pinning layer, a pinned layer, a tunneling layer, a free layer and a top electrode layer stacked in sequence.

[0081] Specifically, the free layer is close to the top electrode layer or the bottom electrode layer, the tunnel layer is close to the free layer, the pinned layer is close to the tunnel layer, and the pinned layer is close to the pinned layer; then the magnetic tunnel junction converts the magnetic field signal of the external magnetic field into the resistance change of the magnetic tunnel junction through the tunneling magnetoresistance effect, thereby realizing the magnetic field induction of the external magnetic field.

[0082] The magnetic tunnel junctions in the magnetoresistive bridge arm of the embodiment of the present invention are electrically coupled to each other through the top electrode layer and / or the bottom electrode layer. Specifically, when the magnetic tunnel junctions are connected in parallel, the top electrode layer and the bottom electrode layer are electrically coupled to each other; when the magnetic tunnel junctions are connected in series, the top electrode layer or the bottom electrode layer is electrically coupled to each other.

[0083] It should be understood that the bandwidth of the magnetoresistive sub-element can be increased by the parallel coupling of the compensation resistor. The bandwidth of the magnetoresistive sub-element depends on the resistance value of the compensation resistor. The bandwidth of the magnetoresistive sub-element can be higher than 1 MHz.

[0084] It should be understood that, while the compensation resistor of the present invention increases the bandwidth of the magnetoresistive element, it also reduces the sensitivity of the magnetoresistive element to a certain extent. The selection of the compensation resistor should be considered comprehensively in combination with the bandwidth and sensitivity.

[0085] The embodiment of the present invention also discloses a sensor device, which includes the above-mentioned magnetoresistive element. The sensor device can realize but is not limited to realizing magnetic field sensing, position sensing, angle sensing, and current sensing.

[0086] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A magnetoresistive element, characterized in that: comprising at least one magnetoresistive element; The magnetic resistance sub-element comprises a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm coupled to each other to form a Wheatstone bridge structure; when there is a zero magnetic field, the resistances of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are the same; At least one of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm comprises a magnetoresistive bridge arm and a compensation resistor; the compensation resistor is coupled in parallel with the magnetoresistive bridge arm, and is used to make the resistance of the at least one bridge arm lower than the resistance of the magnetoresistive bridge arm; The magnetoresistive bridge arm includes at least one magnetic tunnel junction, each of the magnetic tunnel junctions has the same magnetic sensitive axis, and the magnetic sensitive axis is parallel or perpendicular to the free layer plane.

2. The magnetoresistive element according to claim 1, wherein: The first bridge arm includes a first magnetoresistance bridge arm and a first compensation resistor, the second bridge arm includes a second magnetoresistance bridge arm and a second compensation resistor, the third bridge arm includes a third magnetoresistance bridge arm and a third compensation resistor, and the fourth bridge arm includes a fourth magnetoresistance bridge arm and a fourth compensation resistor; Under an external magnetic field within a preset range, the resistances of the first compensation resistor, the second compensation resistor, the third compensation resistor and the fourth compensation resistor remain unchanged; Under the external magnetic field within the preset range, the first magnetoresistance bridge arm and the third magnetoresistance bridge arm have a first resistance change value, and the second magnetoresistance bridge arm and the fourth magnetoresistance bridge arm have a second resistance change value different from the first resistance change value.

3. The magnetoresistive element according to claim 2, characterized in that The first compensation resistor, the second compensation resistor, the third compensation resistor and the fourth compensation resistor have the same resistance; When there is a zero magnetic field, the resistances of the first magnetoresistance bridge arm, the second magnetoresistance bridge arm, the third magnetoresistance bridge arm and the fourth magnetoresistance bridge arm are the same; The first resistance change value is opposite to the second resistance change value.

4. The magnetoresistive element according to claim 3, characterized in that The bandwidth of the magnetoresistive element is related to the bandwidth of the magnetoresistive bridge arm, the resistance value of the magnetoresistive bridge arm under zero magnetic field and the resistance value of the compensation resistor; The greater the ratio of the resistance value of the magnetoresistive bridge arm under zero magnetic field to the resistance value of the compensation resistor, the greater the bandwidth of the magnetoresistive sub-element.

5. The magnetoresistive element according to claim 3, characterized in that Under the external magnetic field within the preset range, the ratio of the sensitivity of the magnetoresistive element to the sensitivity of the magnetoresistive bridge arm is r / (r+R_1); Wherein, r is the resistance value of the compensation resistor; R_1 is the resistance value of the magnetoresistive bridge arm in zero magnetic field.

6. The magnetoresistive element according to claim 1, wherein: The first bridge arm includes a first magnetoresistance bridge arm and a first compensation resistor, the second bridge arm includes only a second magnetoresistance bridge arm, the third bridge arm includes a third magnetoresistance bridge arm and a third compensation resistor, and the fourth bridge arm includes only a fourth magnetoresistance bridge arm; Under zero magnetic field, the resistance value of the first bridge arm after the first magnetoresistance bridge arm is coupled in parallel with the first compensation resistor and the resistance value of the third bridge arm after the third magnetoresistance bridge arm is coupled in parallel with the third compensation resistor are equal to the resistance value of the second magnetoresistance bridge arm or the fourth magnetoresistance bridge arm; Under an external magnetic field within a preset range, the resistance value of the first compensation resistor is the same as the resistance value of the second compensation resistor.

7. The magnetoresistive element according to any one of claims 1 to 6, characterized in that: The compensation resistor comprises: A compensating magnetoresistance, comprising at least one magnetic tunnel junction; the compensating magnetoresistance has a first resistance in a zero magnetic field; A shielding member covers the surface of the compensating magnetic resistor and is used to keep the resistance of the compensating magnetic resistor at the first resistance under a magnetic field within a preset range.

8. The magnetoresistive element according to any one of claims 1 to 6, characterized in that: The magnetic tunnel junction comprises a top electrode layer, a pinning layer, a pinned layer, a tunneling layer, a free layer and a bottom electrode layer; the free layer is close to the top electrode layer or the bottom electrode layer, the tunneling layer is close to the free layer, the pinned layer is close to the tunneling layer, and the pinning layer is close to the pinned layer; The at least one magnetic tunnel junction is electrically coupled to each other through the top electrode layer and / or the bottom electrode layer; The magnetoresistive bridge arm is electrically coupled to the compensation resistor through the top electrode layer and the bottom electrode layer.

9. The magnetoresistive element according to claim 1, characterized in that: The bandwidth of the magnetoresistive element is higher than 1 MHz.

10. A sensing device, characterized in that: including a magnetoresistive element; The magnetoresistive element is the magnetoresistive element according to any one of claims 1 to 9.

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