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WO2013182036A1 - 一种磁电阻齿轮传感器 - Google Patents

一种磁电阻齿轮传感器 Download PDF

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Publication number
WO2013182036A1
WO2013182036A1 PCT/CN2013/076707 CN2013076707W WO2013182036A1 WO 2013182036 A1 WO2013182036 A1 WO 2013182036A1 CN 2013076707 W CN2013076707 W CN 2013076707W WO 2013182036 A1 WO2013182036 A1 WO 2013182036A1
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WIPO (PCT)
Prior art keywords
mtj
magnetic
bridge
magnetoresistive
layer
Prior art date
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Ceased
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PCT/CN2013/076707
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English (en)
French (fr)
Inventor
白建民
吕华
迪克•詹姆斯•G
沈卫锋
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MultiDimension Technology Co Ltd
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MultiDimension Technology Co Ltd
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Publication date
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Priority to JP2015515381A priority Critical patent/JP6189426B2/ja
Priority to EP13800125.0A priority patent/EP2860530A4/en
Priority to US14/405,736 priority patent/US10060941B2/en
Publication of WO2013182036A1 publication Critical patent/WO2013182036A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/488—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by variable reluctance detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/142—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/02—Indicating direction only, e.g. by weather vane
    • G01P13/04—Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement
    • G01P13/045—Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement with speed indication
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/50—Devices characterised by the use of electric or magnetic means for measuring linear speed
    • G01P3/54—Devices characterised by the use of electric or magnetic means for measuring linear speed by measuring frequency of generated current or voltage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G01R33/098—Magnetoresistive devices comprising tunnel junctions, e.g. tunnel magnetoresistance sensors

Definitions

  • the invention relates to the technical field of gear sensors, in particular to a magnetoresistive gear sensor with an MTJ component as a sensitive component.
  • Gear sensors are mainly used in automated control systems to measure the speed and direction of rotation of the gears.
  • gear sensors are photosensitive sensors and magnetic sensors.
  • the magnetic sensor In the mechanical rotating system, the magnetic sensor has a greater advantage than the photosensitive sensor in the harsh environment such as vibration, impact, and oil.
  • Hall Hall
  • AMR anisotropic magnetoresistance
  • GMR giant magnetoresistance
  • the magnetic sensor with the Hall element as the sensitive element has very low sensitivity, and it is usually required to use a polymagnetic ring structure to amplify the magnetic field to improve the sensitivity of the Hall element, which increases the volume and weight of the sensor in which the Hall element is a sensitive element.
  • a sensor in which a Hall element is a sensitive element has a drawback of high power consumption and poor linearity.
  • the sensitivity of AMR components is much higher than that of Hall components, but the linear operating area of AMR components is narrow.
  • Magnetic sensors with AMR components as sensitive components require a 'set/reset' coil to preset them - Reset operation, which not only complicates the manufacturing process of the magnetic sensor in which the AMR element is a sensitive element, but also increases the size and power consumption of the magnetic sensor in which the AMR element is a sensitive element.
  • GMR A magnetic sensor whose component is a sensitive component has higher sensitivity than a sensor whose Hall component is a sensitive component, but a linear working area of a magnetic sensor in which a GMR component is a sensitive component is narrow.
  • GMR The response curve of the component is evenly symmetrical, so a magnetic sensor with a GMR component as a sensitive component can only measure a unipolar gradient magnetic field and cannot measure a bipolar gradient magnetic field.
  • MTJ magnetic tunnel junction
  • MMR tunneling magnetoresistance
  • the Tunnel Magnetoresistance effect senses the magnetic field.
  • MTJ components are compared to previously applied AMR components and GMR The component has a greater rate of change in resistance. Compared to Hall elements, MTJ components have better temperature stability, higher sensitivity, lower power consumption, and better linearity, and do not require an additional magnetic ring structure.
  • MTJ components have better temperature stability, higher sensitivity, and a wider linear working area, and do not require an additional 'set/reset' coil structure.
  • MTJ components have better temperature stability, higher sensitivity, lower power consumption and a wider linear operating area.
  • a magnetic sensor commonly used for gear sensing uses a printed circuit board (PCB) structure.
  • PCB gear sensors are typically constructed of magnetic sensor chips, peripheral circuits, and permanent magnets.
  • the magnetic sensor chip senses the change of the external magnetic field H apply generated by the permanent magnet at the physical position thereof and outputs the sensing signal, and the peripheral circuit processes and converts the sensing signal outputted by the magnetic sensor chip.
  • the change in the external magnetic field H apply generated by the permanent magnet at the physical location of the magnetic sensor chip is very weak. Therefore, in the application of the PCB type gear sensor, whether or not the interference of the interference magnetic field other than the external magnetic field H apply generated by the permanent magnet can be prevented becomes a technical problem to be solved.
  • the magnetic sensor with the MTJ component as the sensitive component still has the following disadvantages:
  • External magnetic field H (1) apply the permanent magnets along the direction of the MTJ element sensitive component is large, resulting in the MTJ element by departing from the linear region of operation and performance degradation, even due to the MTJ element lead saturated and unable to work;
  • a magnetoresistive gear sensor includes a magnetic sensor chip and a first permanent magnet, the magnetic sensor chip including at least one bridge, the bridge Each of the bridge arms includes at least one MTJ component set.
  • the magnetoresistive gear sensor further includes a magnetic sensor chip and the first permanent magnet A concave soft magnet is interposed, and the opening of the soft magnet faces the magnetic sensor chip.
  • the at least one MTJ component group is a plurality of MTJ component groups, and the plurality of MTJ component groups Connected in series and / or in parallel.
  • the plurality of MTJ element groups are connected in series and/or in parallel in the same sensitive direction.
  • each of the bridge arms comprising the MTJ component group has the same sensitive direction.
  • the bridge is a half bridge, a full bridge or a double full bridge.
  • each MTJ component group includes a plurality of MTJ components connected in series and/or in parallel.
  • each MTJ component group includes a plurality of MTJ components connected in series and/or in parallel in the same sensitive direction.
  • each MTJ component It is a multilayer film structure including a pinned layer, a pinned layer, a tunnel barrier layer, and a magnetic free layer which are sequentially deposited.
  • a pair of second permanent magnets are disposed on both sides of each of the MTJ component groups, and the pair of second permanent magnets are opposite to the MTJ
  • the sensitive direction of the component group is tilted to provide a bias magnetic field to the MTJ component group.
  • a pair of second permanent magnets are disposed on both sides of each of the MTJ component groups, and the pair of second permanent magnets are opposite to the MTJ
  • the sensitive direction of the component group is tilted to eliminate the Neil coupling field of the MTJ component group.
  • each pair of second permanent magnets is obliquely disposed with respect to a sensitive direction of the corresponding MTJ element group, and is further used to eliminate the MTJ The Neil coupling field of the component group.
  • each MTJ component It is a multilayer film structure including a pinned layer, a pinned layer, a tunnel barrier layer, a magnetic free layer, and a bias layer which are sequentially deposited.
  • each MTJ element further includes an isolation layer disposed between the magnetic free layer and the bias layer.
  • the magnetoresistive gear sensor further includes a control circuit electrically coupled to the magnetic sensor chip.
  • control circuit is based on The corresponding relationship between the voltage signal outputted by the magnetic sensor chip and the gear tooth position point determines the position of the gear teeth.
  • the magnetic sensor chip comprises a double full bridge
  • each bridge arm of the double full bridge comprises an MTJ component group
  • the control circuit is The voltage signal output by the magnetic sensor chip determines the direction of motion of the gear.
  • the magnetoresistive gear sensor further includes a housing.
  • the sensor uses the MTJ component as the sensitive component, and the Hall component, the AMR component or the GMR Compared with sensors with sensitive components, the sensor has better temperature stability, higher sensitivity, lower power consumption, better linearity, wider linear working area and simpler structure.
  • the sensor is provided with a concave soft magnetic body, so that the external magnetic field generated by the permanent magnet is along the MTJ element.
  • the component of the sensitive direction is reduced, thereby ensuring that the MTJ component in the magnetic sensor chip operates in its linear working area, so that the performance of the sensor is significantly improved;
  • the magnetic sensor chip of the sensor adopts a full bridge, so that the sensor is not easily subjected to the removal of the permanent magnet Interference from disturbing magnetic fields other than the generated external magnetic field;
  • a pair of inclined permanent magnets are disposed on both sides of the MTJ element group, and the magnetic field generated by the inclined permanent magnet is perpendicular to The component of the MTJ component's sensitive direction provides a biasing magnetic field for the MTJ component.
  • MTJ can be adjusted by changing the bias magnetic field The saturation field of the component to obtain a sensor with high sensitivity, or a sensor with different sensitivity as needed;
  • a pair of inclined permanent magnets are disposed on both sides of the MTJ element group, and the magnetic field along the inclined permanent magnet
  • the component of the sensitive direction of the MTJ component can eliminate the Neil coupling field of the MTJ component, thereby ensuring that the operating point of the MTJ component is in its linear working area, improving the linearity of the sensor;
  • the magnetic free layer of the MTJ element is provided with a bias layer capable of providing a perpendicular to the magnetic free layer
  • the bias field of the MTJ component in the sensitive direction can be adjusted by changing the bias magnetic field The saturation field of the component to obtain a sensor with high sensitivity, or a sensor with different sensitivity as needed;
  • the sensor can determine the position of a tooth in the gear, and when the gear is missing, the position of the missing tooth can also be determined;
  • the sensor can not only determine the moving speed of the gear but also determine the moving direction of the gear;
  • the sensor is suitable for both linear gears and circular gears
  • the sensor is advantageous for achieving low-cost mass production.
  • FIG. 1 is a schematic structural diagram of a first MTJ component 11 according to Embodiment 1 of the present invention.
  • FIG. 4 is a schematic diagram of a plurality of first MTJ elements 11 connected in series to a first MTJ element group 13;
  • Figure 5 is a schematic view showing a pair of inclined permanent magnets 14 disposed on both sides of the first MTJ element group 13;
  • Figure 6 is a cross-sectional view showing the distribution of the magnetic field around a pair of inclined permanent magnets on both sides of the first MTJ element group 13;
  • Figure 7 is a plan view showing a pair of inclined permanent magnets 14 disposed on both sides of the first MTJ element group 13;
  • Figure 8 is a plan view of the physical position of the half bridge 15;
  • Figure 9 is an equivalent circuit diagram of the half bridge 15 shown in Figure 8.
  • Figure 10 is a top view of the physical location of the full bridge 16
  • FIG 11 is an equivalent circuit diagram of the full bridge 16 shown in Figure 10;
  • Figure 12 is a graph of the actual measured output voltage of a magnetic field sensor using a full bridge 16
  • Figure 13 is a top view of the physical position of the double full bridge 17;
  • Figure 14 is an equivalent circuit diagram of the double full bridge 17 shown in Figure 13;
  • FIG. 15 is a schematic structural view of a magnetoresistive gear sensor 18 according to Embodiment 1 of the present invention.
  • FIG. 16 is a schematic diagram of a voltage signal of a sinusoidal waveform outputted by the magnetoresistive gear sensor 18 according to Embodiment 1 of the present invention.
  • Figure 17 is a magnetoresistive gear sensor provided by Embodiment 1 of the present invention when the gear is missing teeth. Schematic diagram of the output sinusoidal waveform and the square waveform voltage signal;
  • FIG. 18 is a schematic diagram of a dual voltage signal outputted by the magnetoresistive gear sensor 18 according to Embodiment 1 of the present invention.
  • FIG. 19 is a schematic structural diagram of a second MTJ component 21 according to Embodiment 2 of the present invention.
  • FIG. 1 is a schematic structural diagram of a first MTJ component 11 provided in this embodiment.
  • the first MTJ element 11 is a multilayer film structure, as shown in FIG. 1, which includes an insulating layer 112, a bottom electrode layer 113, a pinning layer 114, a pinned layer 115, and a tunnel barrier which are sequentially deposited on the substrate 111.
  • the pinned layer 115 and the magnetic free layer 117 are ferromagnetic layers, and the material thereof includes, for example, Fe, Co, Ni, FeCo, FeNi, FeCoB, or FeCoNi.
  • the pinned layer 115 may also be a composite layer formed of a ferromagnetic layer, a Ru layer, and a ferromagnetic layer, such as a composite layer formed of a FeCo layer, a Ru layer, and an FeCo layer.
  • the exchange coupling between the pinning layer 114 and the pinned layer 115 causes the direction of the magnetic moment 1151 of the pinned layer 115 to be pinned in one direction, and the direction of the magnetic moment 1151 remains unchanged under the action of the external magnetic field H apply .
  • the pinning layer 114 is an antiferromagnetic layer, and its material includes, for example, PtMn, IrMn, or FeMn.
  • the material of the tunnel barrier layer 116 includes, for example, MgO or Al 2 O 3 .
  • the magnetic moment direction 1171 of the magnetic free layer 117 can vary with the change of the external magnetic field H apply . Under the action of the external magnetic field H apply , the magnetic moment direction 1171 of the magnetic free layer 117 can be gradually changed from the direction parallel to the magnetic moment direction 1151 of the pinned layer 115 to be antiparallel to the magnetic moment direction 1151 of the pinned layer 115. Direction, and vice versa.
  • the magnetic moment direction 1171 of the magnetic free layer 117 is defined as the sensitive direction of the first MTJ element 11.
  • the top electrode layer 118 and the bottom electrode layer 113 are typically made of a non-magnetic conductive material.
  • the material of the substrate 111 is usually silicon, quartz, heat resistant glass, GaAs, or AlTiC.
  • the area of the insulating layer 112 is larger than the area of the bottom electrode layer 113.
  • the top electrode layer 118 and the bottom electrode layer 113 are used to electrically connect with other components. In the present embodiment, the top electrode layer 118 and the bottom electrode layer 113 are electrically connected to, for example, the ohmmeter 12 to measure the resistance of the first MTJ element 11.
  • the magnitude of the resistance of the first MTJ element 11 is related to the relative orientation of the magnetic free layer 117 and the magnetic moment of the pinned layer 115.
  • the resistance value of the first MTJ element 11 is the smallest, which is called the first MTJ element 11 is in a low resistance state; when the magnetic free layer
  • the resistance value of the first MTJ element 11 is the largest, and the first MTJ element 11 is referred to as the high resistance state.
  • the resistance value of the first MTJ element 11 can be linearly changed between the high resistance state and the low resistance state as the external magnetic field H apply changes.
  • the response curve of the resistance of the first MTJ element 11 to the external magnetic field H apply is as shown in FIG. 2, and the external magnetic field H apply is in the sensitive direction of the first MTJ element 11.
  • the first MTJ element 11 When the first MTJ element 11 is in a low resistance state or a high resistance state, its response curve is saturated.
  • the resistance value when the first MTJ element 11 is in the low resistance state is marked as, for example, R L ; and the resistance value when the first MTJ element 11 is in the high resistance state is marked as, for example, R H .
  • the resistance value R of the first MTJ element 11 varies linearly with the change of the external magnetic field H apply .
  • the slope of the response curve of the resistance value R of the first MTJ element 11 to the external magnetic field H apply is defined as the sensitivity of the first MTJ element 11.
  • H O is often referred to as a Neel Coupling field. In general, the Neel coupling field H O ranges from 1 to 40 Oe.
  • the resistance value R of the first MTJ element 11 can be approximated as:
  • H S represents a saturation field.
  • the resistance value R of the first MTJ element 11 is a perfect linear relationship with the change of the external magnetic field H apply , and there is no hysteresis.
  • the response curve of the resistance of the first MTJ element 11 to the external magnetic field H apply is a curve, as shown in FIG.
  • the resistance of the first MTJ element 11 to the external magnetic field H apply will be more curved.
  • first MTJ elements 11 can be connected in series and/or in parallel to form a first MTJ. Component group.
  • the first MTJ element group 13 is formed by connecting six first MTJ elements 11 in series, as shown in FIG. 4, and the first six MTJ element groups 13 are six first.
  • the sensitive direction of the MTJ component 11 is the same as 1171.
  • the first MTJ component group 13 is electrically connected to other components such as the ohmmeter 12. When there is current 131 flowing through the first MTJ component group At 13 o'clock, the direction of current 131 is shown in Figure 4. Normally, the direction of current 131 does not affect the resistance of MTJ component group 13.
  • a first MTJ component group 13 can be used as a bridge arm of the bridge, or it can be connected in series A plurality of first MTJ component groups 13 in parallel or in parallel are used as one bridge arm of the bridge.
  • one side may be disposed on either side of the first MTJ element 11 or the first MTJ element group 13 Pair of inclined permanent magnets 14.
  • a pair of permanent magnets 14 are provided on both sides of, for example, the first MTJ element group 13, and the permanent magnets 14 are placed obliquely with respect to the sensitive direction 1171 of the first MTJ element group 13.
  • the shape of the permanent magnet 14 is, for example, a rectangular parallelepiped.
  • the complementary angle between the long side of the permanent magnet 14 and the sensitive direction 1171 of the first MTJ element group 13 is defined as the inclination angle ⁇ sns of the permanent magnet 14.
  • the length, width and thickness of each permanent magnet 14 are L, W and t, respectively, and the gap between the two permanent magnets 14 is G.
  • the magnetic field H mag of the gap position of the two permanent magnets 14 is considered to be generated by the magnetic charges of the edges of the two permanent magnets 14, and the magnetic field H mag is related to the shape and boundary conditions of the permanent magnets 14. As shown in FIG 7, the angle defined between the sensitive direction of remanent magnetization M r 141 and the permanent magnets 14 of the first MTJ element 13 is set to 1171 M r permanent remanence inclination angle ⁇ mag 141 14.
  • the magnetic charge density r s at the edge of the permanent magnet 14 is related to the magnitude of the residual magnetization M r 141 of the permanent magnet 14 , the inclination angle ⁇ mag of the residual magnetization M r 141 of the permanent magnet 14 , and the inclination angle ⁇ sns of the permanent magnet 14 .
  • the magnetic charge density r s at the edge of the permanent magnet 14 can be expressed as:
  • the magnetic field H mag generated by the magnetic charge at the edge of the permanent magnet 14 can be expressed as:
  • the magnetic field H of the magnetic charge edge 14 mag of the permanent magnets in the vertical bias magnetic field H is defined as the component sensitive to Cross direction 13 of the first MTJ element group 1171.
  • the bias magnetic field H cross can be expressed as:
  • the magnetic field H of the magnetic charge edge 14 generated by the permanent mag 1171 along the sensitive direction of the first MTJ element 13 is set OFF component H can be expressed as:
  • the magnetic field H mag generated by the magnetic charge at the edge of the permanent magnet 14 can be changed along the first MTJ element group.
  • the component H off of the sensitive direction 1171 of 13 is to eliminate the Neil coupling field H O of the first MTJ element 11 itself, ensuring that the operating point of the first MTJ element 11 is in its linear working area.
  • FIG. 8 is a top view of the physical position of the half bridge 15 in the XY plane.
  • Figure 9 shows the equivalent circuit diagram of the half bridge 15.
  • the half bridge 15 comprises two bridge arms 151 and 152, both of which employ, for example, a first MTJ component group 13, the resistance values of which are, for example, R1 and R2, respectively.
  • the sensitive directions of the bridge arms 151 and the bridge arms 152 are all in the sensitive direction 1171.
  • An external magnetic field H apply having a gradient of magnetic field strength is applied in the sensitive direction 1171. As shown in FIG. 8, the magnetic field strength of the external magnetic field H apply at the physical position where the bridge arm 151 is located is outside the physical position of the bridge arm 152.
  • the magnetic field H apply has a different magnetic field strength.
  • a pair of inclined permanent magnets 14 are disposed on both sides of the bridge arm 151 and the bridge arm 152.
  • the two inputs of the half bridge 16 are IN1 and IN2, for example the input IN2 is grounded.
  • the output of half bridge 16 is OUT1.
  • Figure 10 is a top view of the physical location of the full bridge 16.
  • Figure 11 shows the equivalent circuit diagram of the full bridge 16.
  • the full bridge 16 includes four bridge arms 161, 162, 163 and 164, each of which uses two first MTJ component groups 13 connected in series, the resistance values of which are R3, R4, R5 and R6.
  • the sensitive directions of the bridge arms 161, the bridge arms 162, the bridge arms 163, and the bridge arms 164 are all in the sensitive direction 1171.
  • An external magnetic field H apply having a gradient of magnetic field strength is applied in the sensitive direction 1171. As shown, the different magnetic field strength of the external magnetic field H apply the magnetic field strength at the physical location of the external magnetic field at a physical location where the arm 162 and the arm 161 H apply the arm 163 and the arm 164 is located 10.
  • a pair of inclined permanent magnets 14 are respectively disposed on both sides of each of the bridge arms 161, the bridge arms 162, the bridge arms 163, and the bridge arms 164.
  • the two inputs of the full bridge 16 are IN3 and IN4 respectively, for example, the input terminal IN4 is grounded.
  • the two outputs of full bridge 16 are OUT2 and OUT3 respectively.
  • the full bridge 16 output voltage signal V OUT2 does not respond to the common mode magnetic field H cM , but is responsive to the differential mode magnetic field H dM .
  • the resistance values of the bridge arm 161 , the bridge arm 162 , the bridge arm 163 , and the bridge arm 164 are the same, so the full bridge 16 does not output a voltage signal.
  • the senor can also use two full bridges, namely double full bridges.
  • Figure 13 is a top plan view of the physical position of the double full bridge 17.
  • Figure 14 shows the equivalent circuit diagram of the dual full bridge 17.
  • the double full bridge 17 includes eight bridge arms 171, 172, 173, 174, 175, 176, 177 and 178, each of which uses, for example, three parallel first MTJ component groups 13, the resistance of the eight bridge arms
  • the values are R7, R8, R9, R10, R11, R12, R13, and R14. As shown in Fig.
  • the bridge arm 171, the bridge arm 172, the bridge arm 173, and the bridge arm 174 constitute a full bridge
  • the bridge arm 175, the bridge arm 176, the bridge arm 177, and the bridge arm 178 constitute a full bridge.
  • the eight bridge arms of the double full bridge 17 are in the sensitive direction 1171.
  • An external magnetic field H apply having a gradient of magnetic field strength is applied in the sensitive direction 1171.
  • the magnetic field strength of the external magnetic field H apply the magnetic field strength at the physical location of the external magnetic field at the physical location of arm 171 and arm 172 H apply the arm 173 and the arm 174 is located 13 different; bridge different external magnetic field strength H apply the magnetic field strength at the physical location of the external magnetic field H apply at the physical location where the arm 176 and the arm 175 and the arm 177 and the arm 178 is located.
  • a pair of inclined permanent magnets 14 are disposed on both sides of each of the bridge arms of the double full bridge 17.
  • the two inputs of the dual full bridge 17 are IN5 and IN6, for example, the input IN6 is grounded.
  • the four outputs of the dual full bridge 17 are OUT4, OUT5, OUT6, and OUT7.
  • Steady voltage V bias is applied between the input terminal and the input terminal IN5 IN6, the resistance value of the resistance value of the bridge arm 171 of the change resistance value R8 R9 or arm 174 of the arm 173 and the size of R7 or arm 172 R10 varies in magnitude, and the resistance value R11 of the bridge arm 175 or the resistance value R12 of the bridge arm 176 is different from the resistance value R13 of the bridge arm 177 or the resistance value R14 of the bridge arm 178.
  • the half bridge 15, the full bridge 16 or the double full bridge 17 It can be prepared in one time on the same substrate by the same process, usually called a single chip magnetoresistive sensor; or a plurality of first MTJ elements can be prepared by the same process on the same substrate. Then, the plurality of first MTJ elements 11 are cut and packaged separately, and the first MTJ element 11 is electrically connected into a plurality of first MTJ element groups 13 by wires, and the plurality of first MTJs are further connected. Component group 13 is electrically connected to a half bridge 15 , full bridge 16 or double full bridge 17 .
  • a magnetoresistive sensor in a single chip package or a magnetoresistive sensor in a multi-chip package can be connected to an ASIC through its external pad (Application Specific Integrated Circuit, ASIC) or lead frame on the package leads.
  • ASIC Application Specific Integrated Circuit
  • the magnetoresistive gear sensor 18 includes a magnetic sensor chip 181, a permanent magnet 182, a control circuit 183, a concave soft magnet 184, and a housing 185.
  • the magnetic sensor chip 181, the permanent magnet 182, the control circuit 183, and the soft magnetic 184 are integrated in the outer casing 185.
  • the magnetic sensor chip 181 includes at least one bridge, which is a half bridge 15, a full bridge 16 or a double full bridge 17, each bridge arm of the half bridge 15, full bridge 16 or double full bridge 17 includes at least one first MTJ component Group 13, the first set of MTJ elements 13 includes a plurality of first MTJ elements 11 connected in series and/or in parallel.
  • the magnetic sensor chip 181 is electrically connected to the control circuit 183.
  • the soft magnet 184 is disposed between the magnetic sensor chip 181 and the permanent magnet 182, and the opening of the soft magnetic 184 faces the magnetic sensor chip 181.
  • the magnetic sensor chip 181 includes a double full bridge 17, and each of the bridge arms 17 includes a first MTJ component group 13.
  • the permanent magnet 182 is used to generate an external magnetic field H apply and magnetizes a gear made of a ferromagnetic material.
  • the soft magnet 184 is used to reduce the component of the external magnetic field H apply generated by the permanent magnet 182 in the sensitive direction 1171, thereby ensuring that the first MTJ element 11 in the magnetic sensor chip 181 operates in its linear working area.
  • the magnetic sensor chip 181 is for sensing a change in the magnetic field strength of the external magnetic field H apply at its position and outputting a voltage signal to the control circuit 183.
  • the control circuit 183 is for processing and converting the voltage signal output from the magnetic sensor chip 181. In the present embodiment, the control circuit 183 can convert the voltage signal of the sinusoidal waveform output from the magnetic sensor chip 181 into a voltage signal of a square waveform.
  • the magnetoresistive gear sensor 18 is stationary and the gear is moved as shown in FIG.
  • the voltage signal of the sinusoidal waveform output from the magnetoresistive gear sensor 18 is as shown in FIG.
  • the specific position of a tooth to be detected of the gear can be determined based on the correspondence relationship between the sinusoidal waveform and the position point of the voltage signal output from the magnetoresistive gear sensor 18, for example.
  • the voltage signal of the sinusoidal waveform output by the magnetoresistive gear sensor 18 and the voltage signal of the square waveform are as shown in FIG.
  • Whether the gear is missing or not is determined based on, for example, a sinusoidal waveform or a square waveform of a voltage signal output from the magnetoresistive gear sensor 18. If the gear is missing, the specific position of the missing tooth can be determined based on, for example, a sinusoidal waveform or a corresponding relationship between the square waveform and the position point of the voltage signal output from the magnetoresistive gear sensor 18. Since the magnetic sensor chip 181 of the magnetoresistive gear sensor 18 provided in this embodiment adopts the double full bridge 17, the magnetoresistive gear sensor 18 can output the dual voltage signals V OUT4 and V OUT5 as shown in FIG. 18 , according to the two paths The phase difference of the voltage signals V OUT4 and V OUT5 can determine the direction of motion of the gear.
  • the interference magnetic field other than the external magnetic field H apply generated by the permanent magnet 182 at the position where the magnetic sensor chip 181 is located can be regarded as a common mode magnetic field. Since the magnetic sensor chip 181 employs a double full bridge 17, and the double full bridge has a strong ability to suppress common mode magnetic field interference, the magnetoresistive gear sensor 18 is not susceptible to interference magnetic fields other than the external magnetic field H apply generated by the permanent magnet 182. Interference.
  • FIG. 2 is a schematic structural diagram of a second MTJ component 21 according to the embodiment.
  • the second MTJ element 21 is a multilayer film structure, as shown in FIG. 2, which includes an insulating layer 212, a bottom electrode layer 213, a pinning layer 214, a pinned layer 215, and a tunnel barrier which are sequentially deposited on the substrate 211.
  • the pinned layer 215 and the magnetic free layer 217 are ferromagnetic layers.
  • the material of the pinned layer 215 and the magnetic free layer 217 includes Fe, Co, Ni, FeCo, FeNi, FeCo or FeCoNi.
  • the pinned layer 215 may also be a composite layer formed of a ferromagnetic layer, a Ru layer, and a ferromagnetic layer, such as a composite layer formed of a FeCo layer, a Ru layer, and an FeCo layer.
  • the pinning layer 214 is an antiferromagnetic layer made of PtMn, IrMn or FeMn. The exchange coupling between the pinning layer 214 and the pinned layer 215 causes the magnetic moment direction 2151 of the pinned layer 215 to be pinned in one direction, and the magnetic moment direction 2151 remains unchanged under the action of the external magnetic field H apply .
  • the tunnel barrier layer 216 includes MgO or Al 2 O 3 .
  • the magnetic moment direction 2171 of the magnetic free layer 217 can vary as the external magnetic field H apply changes. Under the action of the external magnetic field H apply , the magnetic moment direction 2171 of the magnetic free layer 217 can be gradually changed from the direction parallel to the magnetic moment direction 2151 of the pinned layer 215 to be antiparallel to the magnetic moment direction 2151 of the pinned layer 215. Direction, and vice versa.
  • the bias layer 218 is an antiferromagnetic layer or a permanent magnet layer. The bias layer 218 and the exchange coupling magnetic free layer 217 such that the biasing layer 218 can provide a bias magnetic field H cross sensitivity direction perpendicular to the second MTJ element 21 is a magnetic free layer 217.
  • the saturation field of the second MTJ element 21 can be adjusted by changing the bias magnetic field H cross , thereby adjusting the sensitivity of the second MTJ element 21.
  • the bias layer 218 is an antiferromagnetic layer
  • the blocking temperature of the bias layer 218 is lower than the blocking temperature of the pinned layer 214.
  • Between the free layer 217 and the bias magnetic layer 218 may be deposited isolating layer, for attenuating the bias magnetic field H cross bias layer 218 is provided.
  • the magnitude of the bias magnetic field H cross can be adjusted by changing the thickness of the isolation layer.
  • the spacer layer is typically a non-magnetic material such as Ta, Ru or Cu.
  • the top electrode layer 219 and the bottom electrode layer 213 are generally made of a non-magnetic conductive material.
  • the material of the substrate 211 is usually silicon, quartz, heat resistant glass, GaAs, or AlTiC.
  • the area of the insulating layer 212 is larger than the area of the bottom electrode layer 213.
  • the top electrode layer 219 and the bottom electrode layer 213 are used to electrically connect with other elements.
  • a plurality of second MTJ elements 21 can be connected in series and/or in parallel to form a second MTJ element group.
  • the second MTJ element group 23 is formed by, for example, four second MTJ elements 21 in parallel, and the four second MTJ elements of the second MTJ element group 23 are 21
  • the sensitive direction is the same.
  • the second MTJ component group 23 is electrically connected to other components such as the ohmmeter 12.
  • a second MTJ component group 23 can be used as a bridge arm of the bridge, or it can be connected in series and /
  • a plurality of second MTJ component groups 23 connected in parallel or in parallel are used as one bridge arm of the bridge.
  • each of the bridges of the half bridge 15, the full bridge 16, and the double full bridge 17 employs, for example, a second MTJ element group 23.
  • the sensor uses the MTJ component as a sensitive component, compared to a sensor that uses a Hall component, an AMR component, or a GMR component as a sensitive component.
  • the sensor's temperature stability is better, sensitivity is higher, power consumption is lower, linearity is better, linear working area is wider, and structure is simpler.
  • the sensor is provided with a concave soft magnetic body, so that the external magnetic field generated by the permanent magnet is along the MTJ element. The component in the sensitive direction is reduced, thereby ensuring that the MTJ component in the magnetic sensor chip operates in its linear working area, resulting in a significant improvement in sensor performance.
  • the sensor's magnetic sensor chip uses a full bridge, making the sensor less susceptible to interference from magnetic fields other than the external magnetic field generated by the permanent magnet.
  • MTJ A pair of inclined permanent magnets are disposed on both sides of the element, and the magnetic field generated by the inclined permanent magnet is perpendicular to the sensitive direction of the MTJ element to provide a bias magnetic field for the MTJ element, and the MTJ can be adjusted by changing the bias magnetic field.
  • the saturation field of the component resulting in a sensor with high sensitivity, or a sensor with different sensitivity as needed.
  • MTJ A pair of inclined permanent magnets are arranged on both sides of the component, and the component of the magnetic field generated by the inclined permanent magnet along the sensitive direction of the MTJ component can eliminate the Neil coupling field of the MTJ component, thereby ensuring MTJ The operating point of the component is in its linear working area, improving the linearity of the sensor.
  • the magnetic free layer of the MTJ element is provided with a bias layer capable of providing a magnetic free layer perpendicular to the MTJ.
  • a bias magnetic field in the sensitive direction of the component, by changing the bias magnetic field, the saturation field of the MTJ element can be adjusted to obtain a sensor with high sensitivity, or a sensor with different sensitivity can be realized as needed.
  • the sensor is capable of determining the position of a tooth in the gear and, when the gear is missing, the position of the missing tooth.
  • the sensor not only determines the speed of movement of the gear, but also determines the direction of movement of the gear.
  • the sensor is suitable for both linear gears and round gears. The sensor facilitates low-cost mass production.

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Description

一种磁电阻齿轮传感器
技术领域
本发明涉及齿轮传感器技术领域，特别涉及一种以 MTJ 元件为敏感元件的磁电阻齿轮传感器。
背景技术
齿轮传感器主要应用于自动化控制系统中，以测量齿轮的转速和转动方向。目前，常用的齿轮传感器为光敏传感器和磁传感器。在机械转动系统中，面对震动、冲击、油污等恶劣环境，磁传感器比光敏传感器具有更大的优势。现有技术中有许多不同类型的磁传感器，例如以霍尔（ Hall ）元件、各向异性磁电阻（ AMR ）元件或巨磁电阻（ GMR ）元件为敏感元件的磁传感器。
以霍尔元件为敏感元件的磁传感器灵敏度非常低，通常需要使用聚磁环结构来放大磁场，以提高霍尔元件的灵敏度，这增加了以霍尔元件为敏感元件的传感器的体积和重量。此外，以霍尔元件为敏感元件的传感器具有功耗大、线性度差的缺陷。 AMR 元件的灵敏度比霍尔元件高很多，但是 AMR 元件的线性工作区窄。以 AMR 元件为敏感元件的磁传感器需要设置' set/reset '线圈对其进行预设 - 复位操作，这不仅导致以 AMR 元件为敏感元件的磁传感器的制造工艺复杂，而且使以 AMR 元件为敏感元件的磁传感器的尺寸和功耗均增大。以 GMR 元件为敏感元件的磁传感器较以霍尔元件为敏感元件的传感器具有更高的灵敏度，但是以 GMR 元件为敏感元件的磁传感器的线性工作区偏窄。此外， GMR 元件的响应曲线呈偶对称，因此以 GMR 元件为敏感元件的磁传感器只能测量单极性的梯度磁场，不能测量双极性的梯度磁场。
近年来，一种新型磁电阻效应传感器，即以磁隧道结（ MTJ, Magnetic Tunnel Junction ）元件为敏感元件的磁传感器开始在工业中应用。以 MTJ 元件为敏感元件的磁传感器的工作原理是利用磁性多层膜材料的隧道磁电阻（ TMR, Tunnel Magnetoresistance ）效应对磁场进行感应。 MTJ 元件较之前应用的 AMR 元件和 GMR 元件具有更大的电阻变化率。与霍尔元件相比， MTJ 元件具有更好的温度稳定性、更高的灵敏度、更低的功耗和更好的线性度，并且不需要额外的聚磁环结构。与 AMR 元件相比， MTJ 元件具有更好的温度稳定性、更高的灵敏度和更宽的线性工作区，并且不需要额外的' set/reset '线圈结构。与 GMR 元件相比， MTJ 元件具有更好的温度稳定性、更高的灵敏度、更低的功耗和更宽的线性工作区。
通常用作齿轮传感的磁传感器采用的是印刷电路板（ PCB ）式结构。 PCB 式齿轮传感器通常由磁传感芯片、外围电路和永磁体构成。磁传感芯片感应其所在物理位置处的由永磁体产生的外磁场 Happly 的变化并输出感应信号，外围电路对磁传感芯片输出的感应信号进行处理和转换。磁传感芯片所在物理位置处的由永磁体产生的外磁场 Happly 的变化非常弱。因此，在 PCB 式齿轮传感器的应用中，能否防止除永磁体产生的外磁场 Happly 之外的干扰磁场的干扰成为亟待解决的技术问题。
虽然 MTJ 元件具有极高的灵敏度，但是以 MTJ 元件为敏感元件的磁传感器仍然存在以下不足：
(1) 永磁体产生的外磁场 Happly 沿 MTJ 元件敏感方向的分量很大，导致 MTJ 元件因偏离其线性工作区而性能下降，甚至导致 MTJ 元件因达到饱和而无法工作；
(2) 磁传感芯片感应其所在物理位置处的由永磁体产生的外磁场 Happly 的变化时，容易受到除永磁体产生的外磁场 Happly 之外的干扰磁场的干扰；
(3) 不能确定齿轮中某个齿的位置，当齿轮缺齿时，也不能确定缺齿的具体位置；
(4) 无法确定齿轮的运动方向；
(5) 难于实现低成本的大规模生产。
因此，需要一种能够精确感测齿轮运动状态的齿轮传感器。
发明内容
本发明的目的是提供一种 磁电阻齿轮传感器。
根据本发明提供的 磁电阻齿轮传感器包括磁传感芯片和第一永磁体，所述磁传感芯片包括至少一个电桥， 该电桥 的每一个桥臂包括至少一个 MTJ 元件组 。
优选地 ，所述磁电阻齿轮传感器进一步包括设置于所述磁传感芯片与所述第一永磁体 之间的凹形的软磁体，且所述软磁体的开口朝向 所述磁传感芯片 。
优选地 ， 所述至少一个 MTJ 元件组是 多个 MTJ 元件组，该 多个 MTJ 元件组 串联和/或并联连接。
优选地 ，该多个 MTJ 元件组以相同敏感方向串联和/或并联连接。
优选地 ，每一包括 MTJ 元件组的桥臂具有相同的敏感方向。
优选地 ，所述电桥为半桥、 全桥 或双全桥 。
优选地 ， 每一 MTJ 元件组包括 串联和/或并联连接的多个 MTJ 元件 。
优选地 ， 每一 MTJ 元件组包括以相同敏感方向 串联和/或并联连接的多个 MTJ 元件 。
优选地 ， 每一 MTJ 元件 为多层膜结构，包括依次沉积的钉扎层、被钉扎层、隧道势垒层和磁性自由层。
优选地 ， 所述每一 MTJ 元件组的两侧设有一对第二永磁体，该对第二永磁体相对于该 MTJ 元件组的敏感方向倾斜设置，用于给所述 MTJ 元件组提供偏置磁场 。
优选地 ， 所述每一 MTJ 元件组的两侧设有一对第二永磁体，该对第二永磁体相对于该 MTJ 元件组的敏感方向倾斜设置，用于消除所述 MTJ 元件组的奈耳耦合场 。
优选地 ， 各对第二永磁体相对于对应的 MTJ 元件组的敏感方向倾斜设置，进一步用于消除所述 MTJ 元件组的奈耳耦合场 。
优选地 ， 每一 MTJ 元件 为多层膜结构，包括依次沉积的钉扎层、被钉扎层、隧道势垒层、磁性自由层和偏置层。
更优选地 ， 每一 MTJ 元件 进一步包括设于所述磁性自由层与偏置层之间的隔离层。
优选地 ，所述磁电阻齿轮传感器进一步包括 与 所述磁传感芯片 电连接 的控制电路。
优选地 ， 所述控制电路根据 所述磁传感芯片输出的电压信号与齿轮轮齿位置点的对应关系来确定轮齿的位置。
优选地 ，所述磁传感芯片包括双全桥，所述双全桥的每一桥臂包括 MTJ 元件组， 所述控制电路根据 所述磁传感芯片输出的电压信号来确定齿轮的运动方向。
优选地 ，所述磁电阻齿轮传感器进一步包括外壳。
本发明具有如下有益效果：
(1) 所述 传感器以 MTJ 元件为敏感元件，与以霍尔元件、 AMR 元件或 GMR 元件为敏感元件的传感器相比，所述 传感器 的温度稳定性更好、灵敏度更高、功耗更低、线性度更好、线性工作区更宽、结构更简单；
(2) 所述 传感器设有凹形的软磁体， 使 永磁体 产生的外磁场沿 MTJ 元件 敏感方向的分量减小，从而保证 磁传感芯片 中的 MTJ 元件工作在其线性工作区，使 所述 传感器的性能得到明显改善 ；
(3) 所述 传感器的磁传感芯片采用全桥，使得 所述 传感器不容易受到 除 所述永磁体 产生的外磁场之外的干扰磁场的干扰；
(4) 在一种优选实施例中， MTJ 元件组的两侧设置一对倾斜的永磁体，该倾斜的永磁体产生的磁场垂直于 MTJ 元件敏感方向的分量为 MTJ 元件提供了偏置磁场。通过改变该偏置磁场能够调整 MTJ 元件的饱和场，从而获得具有高灵敏度的传感器，或可根据需要实现不同灵敏度的传感器；
(5) 在一种优选实施例中， MTJ 元件组的两侧设置一对倾斜的永磁体，该倾斜的永磁体产生的磁场沿 MTJ 元件敏感方向的分量能够消除 MTJ 元件的奈耳耦合场，从而保证 MTJ 元件的工作点处于其线性工作区，改善了所述传感器的线性度；
(6) 在另一种优选实施例中， MTJ 元件的磁性自由层上设有偏置层，该偏置层能够为磁性自由层提供垂直于 MTJ 元件敏感方向的偏置磁场 。 通过改变该偏置磁场能够调整 MTJ 元件的饱和场，从而获得具有高灵敏度的传感器，或可根据需要实现不同灵敏度的传感器；
(7) 所述感器能够确定齿轮中某个齿的位置，当齿轮缺齿时，还能够确定缺齿的位置；
(8) 所述传感器不仅能够确定齿轮的运动速度，而且能够确定齿轮的运动方向；
(9) 所述传感器既适用于直线形齿轮，也适用于圆形齿轮；
(10) 所述传感器有利于实现低成本的大规模生产。
附图说明
图 1 为本发明实施例 1 提供的第一 MTJ 元件 11 的结构示意图；
图 2 为理想状态下第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线图，外磁场 Happly 沿第一 MTJ 元件 11 的敏感方向；
图 3 为实际应用中第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线图，外磁场 Happly 沿第一 MTJ 元件 11 的敏感方向；
图 4 为多个第一 MTJ 元件 11 串联成一个第一 MTJ 元件 组 13 的示意图；
图 5 为在第一 MTJ 元件组 13 两侧设置一对倾斜永磁体 14 的示意图；
图 6 为在第一 MTJ 元件组 13 两侧设置一对倾斜永磁体后其周围的磁场分布的剖面图；
图 7 为在第一 MTJ 元件组 13 两侧设置一对倾斜永磁体 14 的俯视图；
图 8 为半桥 15 的物理位置的俯视图；
图 9 为图 8 所示的半桥 15 的等效电路图；
图 10 为全桥 16 的物理位置的俯视图；
图 11 为图 10 所示的全桥 16 的等效电路图；
图 12 为实际测量的采用全桥 16 的磁场传感器的输出电压的曲线图；
图 13 为双全桥 17 的物理位置的俯视图；
图 14 为图 13 所示的双全桥 17 的等效电路图；
图 15 为本发明实施例 1 提供的磁电阻齿轮传感器 18 的结构示意图；
图 16 为本发明实施例 1 提供的磁电阻齿轮传感器 18 输出的正弦波形的电压信号的示意图；
图 17 为当齿轮缺齿时本发明实施例 1 提供的磁电阻齿轮传感器 18 输出的正弦波形和方波形的电压信号的示意图；
图 18 为本发明实施例 1 提供的磁电阻齿轮传感器 18 输出的双路电压信号的示意图；
图 19 为本发明实施例 2 提供的第二 MTJ 元件 21 的结构示意图。
具体实施方式
下面结合附图及实施例对本发明的发明内容作进一步的描述。
实施例 1 ：
图 1 为本实施例提供的第一 MTJ 元件 11 的结构示意图。第一 MTJ 元件 11 为多层膜结构，如图 1 所示，其包括依次沉积在基片 111 上的绝缘层 112 、底电极层 113 、钉扎层 114 、被钉扎层 115 、隧道势垒层 116 、磁性自由层 117 和顶电极层 118 。被钉扎层 115 和磁性自由层 117 为铁磁层，其材质例如包括 Fe 、 Co 、 Ni 、 FeCo 、 FeNi 、 FeCoB 或 FeCoNi 。被钉扎层 115 也可以是铁磁层、 Ru 层和铁磁层形成的复合层，例如 FeCo 层、 Ru 层和 FeCo 层形成的复合层。钉扎层 114 与被钉扎层 115 之间的交换耦合作用使得被钉扎层 115 的磁矩方向 1151 被钉扎在一个方向，且在外磁场 Happly 作用下磁矩方向 1151 保持不变。钉扎层 114 为反铁磁层，其材质例如包括 PtMn 、 IrMn 或 FeMn 。隧道势垒层 116 的材质例如包括 MgO 或 Al2O3 。磁性自由层 117 的磁矩方向 1171 能够随外磁场 Happly 的改变而变化。在外磁场 Happly 的作用下，磁性自由层 117 的磁矩方向 1171 能够从与被钉扎层 115 的磁矩方向 1151 平行的方向逐步改变为与被钉扎层 115 的磁矩方向 1151 反平行的方向，且反之亦然。在本实施例中，磁性自由层 117 的磁矩方向 1171 定义为第一 MTJ 元件 11 的敏感方向。顶电极层 118 和底电极层 113 通常采用非磁性导电材料。基片 111 的材质通常采用硅、石英、耐热玻璃、 GaAs 、或 AlTiC 。绝缘层 112 的面积大于底电极层 113 的面积。顶电极层 118 和底电极层 113 用于与其它元件电连接。在本实施例中，顶电极层 118 和底电极层 113 与例如欧姆计 12 电连接，以测量第一 MTJ 元件 11 的电阻。
第一 MTJ 元件 11 的电阻大小与磁性自由层 117 和被钉扎层 115 的磁矩的相对取向有关。当磁性自由层 117 的磁矩方向 1171 与被钉扎层 115 的磁矩方向 1151 平行时，第一 MTJ 元件 11 的电阻值最小，称为第一 MTJ 元件 11 处于低阻态；当磁性自由层 117 的磁矩方向 1171 与被钉扎层 115 的磁矩方向 1151 反平行时，第一 MTJ 元件 11 的电阻值最大，称为第一 MTJ 元件 11 处于高阻态。利用现有技术能够实现第一 MTJ 元件 11 的电阻值随着外磁场 Happly 的改变在高阻态与低阻态之间线性变化。
在理想状态下，第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线图如图 2 所示，外磁场 Happly 沿第一 MTJ 元件 11 的敏感方向。当第一 MTJ 元件 11 处于低阻态或高阻态时，其响应曲线达到饱和。第一 MTJ 元件 11 处于低阻态时的电阻值被标记为例如 RL ；第一 MTJ 元件 11 处于高阻态时的电阻值被标记为例如 RH 。在高阻态与低阻态之间，第一 MTJ 元件 11 的电阻值 R 随外磁场 Happly 的改变呈线性变化。第一 MTJ 元件 11 的电阻值 R 对外磁场 Happly 的响应曲线的斜率，即第一 MTJ 元件 11 的电阻值 R 随外磁场 Happly 的变化率定义为第一 MTJ 元件 11 的灵敏度。如图 2 所示，第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线 不是关于 Happly=0 的直线成轴对称，而是关于 Happly=HO 的直线成轴对称。 HO 通常被称为奈尔耦合（ Neel Coupling ）场。通常情况下，奈尔耦合场 HO 的取值范围为 1-40 Oe 。
如图 2 所示的响应曲线的线性区内，第一 MTJ 元件 11 的电阻值 R 可以近似表示为：
Figure PCTCN2013076707-appb-I000001
, (1)
式 (1) 中， HS 表示饱和场。饱和场 HS 的定义为：当奈尔耦合场 HO=0 时，第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线的线性区域的切线与正向或负向饱和曲线的切线的交点对应的外磁场值。在理想状态下，第一 MTJ 元件 11 的电阻值 R 随外磁场 Happly 的变化是完美的线性关系，并且没有磁滞。在实际情况下，由于第一 MTJ 元件 11 具有磁滞现象，第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线为一条曲线，如图 3 所示。在实际的传感器应用领域，由于磁传感设计的制约以及材料的缺陷，第一 MTJ 元件 11 的电阻对外磁场 Happly 的响应曲线会更弯曲。
应用中，可以将多个第一 MTJ 元件 11 串联和 / 或并联连接成一个第一 MTJ 元件组。在本实施例中，第一 MTJ 元件组 13 由六个第一 MTJ 元件 11 串联连接而成，如图 4 所示，且第一 MTJ 元件组 13 的六个第一 MTJ 元件 11 的敏感方向 1171 相同。将第一 MTJ 元件组 13 与其它元件例如欧姆计 12 电连接。当有电流 131 流过第一 MTJ 元件组 13 时，电流 131 的方向如图 4 所示。通常情况下，电流 131 的方向并不对 MTJ 元件组 13 的电阻值产生影响。通过改变第一 MTJ 元件组 13 中第一 MTJ 元件 11 的个数可以调整第一 MTJ 元件组 13 的电阻值。可以将一个第一 MTJ 元件组 13 用作电桥的一个桥臂，也可以将串联和 / 或并联的多个第一 MTJ 元件组 13 用作电桥的一个桥臂。
为了给第一 MTJ 元件 11 或第一 MTJ 元件组 13 提供偏置磁场 Hcross ，并消除其奈耳耦合场 HO ，可以在第一 MTJ 元件 11 或第一 MTJ 元件组 13 的两侧设置一对倾斜的永磁体 14 。在本实施例中，如图 5 所示，在例如第一 MTJ 元件组 13 的 两侧设有一对永磁体 14 ，且永磁体 14 相对于第一 MTJ 元件组 13 的敏感方向 1171 倾斜放置。给永磁体 14 充磁后，第一 MTJ 元件组 13 周围的磁场分布如图 6 所示。在本实施例中，永磁体 14 的形状例如为长方体。如图 7 所示，永磁体 14 的长边与第一 MTJ 元件组 13 的敏感方向 1171 之间的夹角的余角定义为永磁体 14 的倾斜角 θsns 。每个永磁体 14 的长度、宽度和厚度分别为 L 、 W 和 t ，两个永磁体 14 之间的间隙为 G 。
两个永磁体 14 的间隙位置的磁场 Hmag 被认为是两个永磁体 14 边缘的磁荷产生的，并且磁场 Hmag 与永磁体 14 的形状和边界条件有关。如图 7 所示， 永磁体 14 的剩磁 Mr141 与第一 MTJ 元件组 13 的敏感方向 1171 之间的夹角定义为永磁体 14 的剩磁 Mr141 的倾斜角 θmag 。永磁体 14 边缘的磁荷密度 r s 与永磁体 14 的剩磁 Mr141 的大小、永磁体 14 的剩磁 Mr141 的倾斜角 θmag 和永磁体 14 的倾斜角 θsns 相关。永磁体 14 边缘的磁荷密度 r s 可表示为：
Figure PCTCN2013076707-appb-I000002
(2)
永磁体 14 边缘的磁荷产生的磁场 Hmag 可以表示为：
Figure PCTCN2013076707-appb-I000003
(3)
如图 7 所示，永磁体 14 边缘的磁荷产生的磁场 Hmag 沿垂直于第一 MTJ 元件组 13 的敏感方向 1171 的分量定义为偏置磁场 Hcross 。当 θmag = θsns = π/2 时，偏置磁场 Hcross 可以表示为：
Figure PCTCN2013076707-appb-I000004
(4)
由式 (4) 可以看出，通过调整两个永磁体 14 的形状、尺寸、二者之间的间隙 G 和剩磁 Mr141 的大小，可以改变第一 MTJ 元件组 13 所在位置的偏置磁场 Hcross 。通过改变偏置磁场 Hcross 能够调整第一 MTJ 元件组 13 的饱和场，进而确定第一 MTJ 元件组 13 的灵敏度。
偏置磁场 Hcross 也可以表示为：
Figure PCTCN2013076707-appb-I000005
(5)
永磁体 14 边缘的磁荷产生的磁场 Hmag 沿第一 MTJ 元件组 13 的敏感方向 1171 的分量 Hoff 可以表示为：
Figure PCTCN2013076707-appb-I000006
(6)
由式 (6) 可以看出，通过调整永磁体 14 的形状、尺寸和剩磁 Mr141 的倾斜角 θmag ，可以改变永磁体 14 边缘的磁荷产生的磁场 Hmag 沿第一 MTJ 元件组 13 的敏感方向 1171 的分量 Hoff ，以消除第一 MTJ 元件 11 本身的奈耳耦合场 HO ，保证第一 MTJ 元件 11 的工作点处于其线性工作区。
图 8 为半桥 15 的物理位置在 X-Y 平面的俯视图。图 9 为半桥 15 的等效电路图。半桥 15 包括两个桥臂 151 和 152 ，该两个桥臂都采用例如一个第一 MTJ 元件组 13 ，该两个桥臂的电阻值例如分别为 R1 和 R2 。桥臂 151 和桥臂 152 的敏感方向都沿敏感方向 1171 。沿敏感方向 1171 施加一磁场强度呈梯度变化的外磁场 Happly ，如图 8 所示，桥臂 151 所在的物理位置处的外磁场 Happly 的磁场强度与桥臂 152 所在的物理位置处的外磁场 Happly 的磁场强度不同。桥臂 151 和桥臂 152 的两侧都设置有一对倾斜的永磁体 14 。半桥 16 的两个输入端为 IN1 和 IN2 ，例如输入端 IN2 接地。半桥 16 的输出端为 OUT1 。在输入端 IN1 与输入端 IN2 之间施加稳恒电压 Vbias ，桥臂 151 的电阻值 R1 的变化大小与桥臂 152 的电阻值 R2 的变化大小不同，因此输出端 OUT1 将输出电压信号 VOUT1=V1 。
图 10 为全桥 16 的物理位置的俯视图。图 11 为全桥 16 的等效电路图。全桥 16 包括四个桥臂 161 、 162 、 163 和 164 ，该四个桥臂都采用两个串联的第一 MTJ 元件组 13 ，该四个桥臂的电阻值分别为 R3 、 R4 、 R5 和 R6 。桥臂 161 、桥臂 162 、桥臂 163 和桥臂 164 的敏感方向都沿敏感方向 1171 。沿敏感方向 1171 施加一磁场强度呈梯度变化的外磁场 Happly 。如图 10 所示，桥臂 161 和桥臂 162 所在的物理位置处的外磁场 Happly 的磁场强度与桥臂 163 和桥臂 164 所在的物理位置处的外磁场 Happly 的磁场强度不同。每一桥臂 161 、桥臂 162 、桥臂 163 和桥臂 164 的两侧分别设置有一对倾斜的永磁体 14 。全桥 16 的两个输入端分别为 IN3 和 IN4 ，例如输入端 IN4 接地。全桥 16 的两个输出端分别为 OUT2 和 OUT3 。在输入端 IN3 与输入端 IN4 之间施加稳恒电压 Vbias ，桥臂 161 的电阻值 R3 或桥臂 162 的电阻值 R4 的变化大小与桥臂 163 的电阻值 R5 或桥臂 164 的电阻值 R6 的变化大小不同，因此，输出端 OUT2 和输出端 OUT3 将分别输出电压 V2 和 V3 ，全桥 16 输出的电压信号为 VOUT2=(V3-V2) 。
在理想情况下，全桥 16 输出的电压信号 VOUT2 对共模磁场 HcM 没有响应，但对差模磁场 HdM 有响应。在共模磁场 HcM 的作用下，桥臂 161 、桥臂 162 、桥臂 163 和桥臂 164 的电阻值变化相同，因此全桥 16 不输出电压信号。在理想情况下，全桥 16 的四个桥臂的电阻值都等于 R ，即 R3=R4=R5=R6=R ，且全桥 1 6 的四个桥臂的灵敏度都等于 SR ，即 SR3=SR4=SR5=SR6=S R ，则有：
Figure PCTCN2013076707-appb-I000007
， (7)
Figure PCTCN2013076707-appb-I000008
， (8)
Figure PCTCN2013076707-appb-I000009
， (9)
由式 (9) 可以看出，全桥 16 输出的电压信号只与差模磁场 HdM 有关，而与共模磁场 HcM 无关。因此，全桥 16 具有很强的抑制共模磁场干扰的能力。全桥 16 的典型输出如图 12 所示。
在实际应用中，传感器也可以采用两个全桥，即双全桥。图 13 为双全桥 17 的物理位置的俯视图。图 14 为双全桥 17 的等效电路图。双全桥 17 包括八个桥臂 171 、 172 、 173 、 174 、 175 、 176 、 177 和 178 ，该八个桥臂都采用例如三个并联的第一 MTJ 元件组 13 ，该八个桥臂的电阻值分别为 R7 、 R8 、 R9 、 R10 、 R11 、 R12 、 R13 和 R14 。如图 14 所示，例如桥臂 171 、桥臂 172 、桥臂 173 和桥臂 174 构成一个全桥，桥臂 175 、桥臂 176 、桥臂 177 和桥臂 178 构成一个全桥。优选地，双全桥 17 的八个桥臂的敏感方向都沿敏感方向 1171 。沿敏感方向 1171 施加一磁场强度呈梯度变化的外磁场 Happly 。如图 13 所示，桥臂 171 和桥臂 172 所在的物理位置处的外磁场 Happly 的磁场强度与桥臂 173 和桥臂 174 所在的物理位置处的外磁场 Happly 的磁场强度不同；桥臂 175 和桥臂 176 所在的物理位置处的外磁场 Happly 的磁场强度与桥臂 177 和桥臂 178 所在的物理位置处的外磁场 Happly 的磁场强度不同。双全桥 17 的每一个桥臂的两侧都设置有一对倾斜的永磁体 14 。双全桥 17 的两个输入端分别为 IN5 和 IN6 ，例如输入端 IN6 接地。双全桥 17 的四个输出端分别为 OUT4 、 OUT5 、 OUT6 和 OUT7 。在输入端 IN5 与输入端 IN6 之间施加稳恒电压 Vbias ，桥臂 171 的电阻值 R7 或桥臂 172 的电阻值 R8 的变化大小与桥臂 173 的电阻值 R9 或桥臂 174 的电阻值 R10 的变化大小不同，桥臂 175 的电阻值 R11 或桥臂 176 的电阻值 R12 的变化大小与桥臂 177 的电阻值 R13 或桥臂 178 的电阻值 R14 的变化大小不同，输出端 OUT4 、输出端 OUT5 、输出端 OUT6 和输出端 OUT7 将分别输出电压 V4 、 V5 、 V6 和 V7 。双全桥 1 7 输出双路电压信号 VOUT4=(V5-V4) 和 VOUT5=(V7-V6) 。
在磁电阻传感器的实际制备中，半桥 15 、全桥 16 或双全桥 17 都可以在同一基片上采用相同的工艺一次性制备完成，通常称为单一芯片磁电阻传感器；也可以在同一基片上采用相同的工艺制备出多个第一 MTJ 元件 11 ，然后将多个第一 MTJ 元件 11 切割后单独封装，并通过引线将第一 MTJ 元件 11 电连接成多个第一 MTJ 元件组 13 ，再将该多个第一 MTJ 元件组 13 电连接成半桥 15 、全桥 16 或双全桥 17 。单一芯片封装的磁电阻传感器或多芯片封装的磁电阻传感器，都可以通过其外接焊盘连接到专用集成电路（ Application Specific Integrated Circuit ， ASIC ）或引线框的封装引脚上。
如图 15 所示，本实施例提供的 磁电阻齿轮传感器 18 包括磁传感芯片 181 、永磁体 182 、控制电路 183 、凹形的软磁体 184 和 外壳 185 。磁传感芯片 181 、永磁体 182 、 控制电路 183 和 软磁体 184 集成于外壳 185 内。磁传感芯片 181 包括至少一个电桥，该电桥为半桥 15 、 全桥 16 或双全桥 17 ，半桥 15 、 全桥 16 或双全桥 17 的每一个桥臂包括至少一个 第一 MTJ 元件组 13 ，第一 MTJ 元件组 13 包括 串联和/或并联的多个 第一 MTJ 元件 11 。磁传感芯片 181 与 控制电路 183 电连接。软磁体 184 设置于磁传感芯片 181 与永磁体 182 之间，且软磁体 184 的开口朝向 磁传感芯片 181 。 在本实施例中，磁传感芯片 181 包括一个双全桥 17 ，双全桥 17 的每一个桥臂包括一个第一 MTJ 元件组 13 。 永磁体 182 用于产生外磁场 Happly 并使由铁磁材料制成的齿轮磁化。软磁体 184 用于使 永磁体 182 产生的外磁场 Happly 沿敏感方向 1171 的分量减小，从而保证 磁传感芯片 181 中的第一 MTJ 元件 11 工作在其线性工作区 。当齿轮与 磁传感芯片 181 之间发生相对运动时， 磁传感芯片 181 所在位置处的外磁场 Happly 的磁场强度将发生变化。 磁传感芯片 181 用于感应其所在位置的外磁场 Happly 的磁场强度的变化并向 控制电路 183 输出电压信号。 控制电路 183 用于对 磁传感芯片 181 输出的电压信号进行处理和转换。在本实施例中， 控制电路 183 能够将 磁传感芯片 181 输出的正弦波形的电压信号转换为方波形的电压信号。
在本实施例中，例如 磁电阻齿轮传感器 18 静止不动，齿轮运动，如图 15 所示。当齿轮上的不同位置点 A 、 B 、 C 、 D 和 E 依次经过 磁电阻齿轮传感器时，磁电阻齿轮传感器 18 输出的例如正弦波形的电压信号如图 16 所示 。根据 磁电阻齿轮传感器 18 输出的电压信号的例如正弦波形与位置点的对应关系即可确定齿轮的一个待检测齿的具体位置 。当齿轮缺齿时，磁电阻齿轮传感器 18 输出的正弦波形的电压信号和方波形的电压信号如图 17 所示。根据磁电阻齿轮传感器 18 输出的电压信号的例如正弦波形或方波形即可确定齿轮是否缺齿。如果齿轮缺齿，根据 磁电阻齿轮传感器 18 输出的电压信号的例如正弦波形或方波形与位置点的对应关系即可确定缺齿的具体位置 。由于本实施例提供的磁电阻齿轮传感器 18 的 磁传感芯片 181 采用双全桥 17 ，因此磁电阻齿轮传感器 18 能够输出双路电压信号 VOUT4 和 VOUT5 ，如图 18 所示，根据该双路电压信号 VOUT4 和 VOUT5 的相位差能够确定齿轮的运动方向。应用 磁电阻齿轮传感器 18 时 ， 磁传感芯片 181 所在的位置处，除 永磁体 182 产生的外磁场 Happly 之外的干扰磁场可以视为共模磁场。由于 磁传感芯片 181 采用双全桥 17 ，并且双全桥具有很强的抑制共模磁场干扰的能力，因此 磁电阻齿轮传感器 18 不容易受到 除 永磁体 182 产生的外磁场 Happly 之外的干扰磁场的干扰。
实施例 2 ：
图 2 为本实施例提供的第二 MTJ 元件 21 的结构示意图。第二 MTJ 元件 21 为多层膜结构，如图 2 所示，其包括依次沉积在基片 211 上的绝缘层 212 、底电极层 213 、钉扎层 214 、被钉扎层 215 、隧道势垒层 216 、磁性自由层 217 、偏置层 218 和顶电极层 219 。被钉扎层 215 和磁性自由层 217 为铁磁层。被钉扎层 215 和磁性自由层 217 的材质包括 Fe 、 Co 、 Ni 、 FeCo 、 FeNi 、 FeCo 或 FeCoNi 。被钉扎层 215 也可以是铁磁层、 Ru 层和铁磁层形成的复合层，例如 FeCo 层、 Ru 层和 FeCo 层形成的复合层。钉扎层 214 为反铁磁层，其材质包括 PtMn 、 IrMn 或 FeMn 。钉扎层 214 与被钉扎层 215 之间的交换耦合作用使得被钉扎层 215 的磁矩方向 2151 被钉扎在一个方向，且在外磁场 Happly 作用下磁矩方向 2151 保持不变。隧道势垒层 216 包括 MgO 或 Al2O3 。磁性自由层 217 的磁矩方向 2171 能够随外磁场 Happly 的改变而变化。在外磁场 Happly 的作用下，磁性自由层 217 的磁矩方向 2171 能够从与被钉扎层 215 的磁矩方向 2151 平行的方向逐步改变为与被钉扎层 215 的磁矩方向 2151 反平行的方向，且反之亦然。偏置层 218 为反铁磁层或永磁层。偏置层 218 与磁性自由层 217 之间的交换耦合作用使得偏置层 218 能够为磁性自由层 217 提供垂直于第二 MTJ 元件 21 的敏感方向的偏置磁场 Hcross 。通过改变偏置磁场 Hcross 能够调整第二 MTJ 元件 21 的饱和场，进而调整第二 MTJ 元件 21 的灵敏度。当偏置层 218 为反铁磁层时，偏置层 218 的阻隔温度 (Blocking Temperature) 要低于钉扎层 214 的阻隔温度。在磁性自由层 217 与偏置层 218 之间也可以沉积一层隔离层，用于减弱偏置层 218 提供的偏置磁场 Hcross 。通过改变隔离层的厚度即可调整偏置磁场 Hcross 的大小。隔离层通常采用非磁性材料例如 Ta 、 Ru 或 Cu 。顶电极层 219 和底电极层 213 通常采用非磁性导电材料。基片 211 的材质通常采用硅、石英、耐热玻璃、 GaAs 、或 AlTiC 。绝缘层 212 的面积大于底电极层 213 的面积。顶电极层 219 和底电极层 213 用于与其它元件电连接。
应用中，可以将多个第二 MTJ 元件 21 串联和 / 或并联成一个第二 MTJ 元件组 23 。在本实施例中，第二 MTJ 元件组 23 由例如四个第二 MTJ 元件 21 并联而成，且第二 MTJ 元件组 23 的四个第二 MTJ 元件 21 的敏感方向相同。将第二 MTJ 元件组 23 与其它元件例如欧姆计 12 电连接。可以将一个第二 MTJ 元件组 23 用作电桥的一个桥臂，也可以将串联和 / 或并联的多个第二 MTJ 元件组 23 用作 电桥 的一个桥臂。需要说明的是，当电桥中采用第二 MTJ 元件组 23 时，不需要在第二 MTJ 元件组 23 的两侧设置倾斜的永磁体 14 。在本实施例中， 半桥 15 、 全桥 16 和双全桥 17 的每一个桥臂采用例如一个第二 MTJ 元件组 23 。
磁电阻齿轮传感器 18 中采用第二 MTJ 元件组 23 的情况与实施例 1 相同。
传感器以 MTJ 元件为敏感元件，与以霍尔元件、 AMR 元件或 GMR 元件为敏感元件的传感器相比， 传感器 的温度稳定性更好、灵敏度更高、功耗更低、线性度更好、线性工作区更宽、结构更简单。 传感器设有凹形的软磁体， 使 永磁体 产生的外磁场沿 MTJ 元件 敏感方向的分量减小，从而保证 磁传感芯片 中的 MTJ 元件工作在其线性工作区，使传感器的性能得到明显改善 。 传感器的磁传感芯片采用全桥，使得传感器不容易受到 除 永磁体 产生的外磁场之外的干扰磁场的干扰。在一种优选实施例中， MTJ 元件的两侧设置一对倾斜的永磁体，该倾斜的永磁体产生的磁场垂直于 MTJ 元件敏感方向的分量为 MTJ 元件提供了偏置磁场，通过改变该偏置磁场能够调整 MTJ 元件的饱和场，从而获得具有高灵敏度的传感器，或可根据需要实现不同灵敏度的传感器。在一种优选实施例中， MTJ 元件的两侧设置一对倾斜的永磁体，该倾斜的永磁体产生的磁场沿 MTJ 元件敏感方向的分量能够消除 MTJ 元件的奈耳耦合场，从而保证 MTJ 元件的工作点处于其线性工作区，改善了传感器的线性度。在另一种优选实施例中， MTJ 元件的磁性自由层上设有偏置层，该偏置层能够为磁性自由层提供垂直于 MTJ 元件敏感方向的偏置磁场 ， 通过改变该偏置磁场能够调整 MTJ 元件的饱和场，从而获得具有高灵敏度的传感器，或可根据需要实现不同灵敏度的传感器。 传感器能够确定齿轮中某个齿的位置，当齿轮缺齿时，还能够确定缺齿的位置。传感器不仅能够确定齿轮的运动速度，而且能够确定齿轮的运动方向。传感器既适用于直线形齿轮，也适用于圆形齿轮。 传感器有利于实现低成本的大规模生产。
应当理解，以上借助优选实施例对本发明的技术方案进行的详细说明是示意性的而非限制性的。本领域的普通技术人员在阅读本发明说明书的基础上可以对各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的精神和范围。

Claims (18)

1. 一种磁电阻齿轮传感器，其特征在于，该传感器包括磁传感芯片 (181) 和第一永磁体 (182) ，所述磁传感芯片 (181) 包括至少一个电桥， 该电桥 的每一个桥臂包括至少一个 MTJ 元件组 (13 ， 23) 。
2. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于，所述磁电阻齿轮传感器进一步包括设置于所述磁传感芯片 (181) 与所述第一永磁体 (182) 之间的凹形的软磁体 (184) ，且所述软磁体 (184) 的开口朝向 所述磁传感芯片 (181) 。
3. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于， 所述至少一个 MTJ 元件组是 多个 MTJ 元件组，该 多个 MTJ 元件组 串联和/或并联连接。
4. 根据权利要求 3 所述的磁电阻齿轮传感器，其特征在于，多个 MTJ 元件组以相同敏感方向串联和/或并联连接。
5. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于，所有包括 MTJ 元件组的桥臂具有相同的敏感方向。
6. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于，所述电桥为半桥 (15) 、 全桥 (16) 或双全桥 (17) 。
7. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于， 每一 MTJ 元件组 (13 ， 23) 包括 串联和/或并联连接的多个 MTJ 元件 (11 ， 21) 。
8. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于， 每一 MTJ 元件组 (13 ， 23) 包括以相同敏感方向 串联和/或并联连接的多个 MTJ 元件 (11 ， 21) 。
9. 根据权利要求 7 或 8 所述的磁电阻齿轮传感器，其特征在于， 每一 MTJ 元件 (11) 为多层膜结构，包括依次沉积的钉扎层 (114) 、被钉扎层 (115) 、隧道势垒层 (116) 和磁性自由层 (117) 。
10. 根据权利要求 9 所述的磁电阻齿轮传感器，其特征在于， 所述每一 MTJ 元件组 (13) 的两侧设有一对第二永磁体 (14) ，各对第二永磁体 (14) 相对于对应的 MTJ 元件组 (13) 的敏感方向倾斜设置，用于给所述 MTJ 元件组 (13) 提供偏置磁场 。
11. 根据权利要求 9 所述的磁电阻齿轮传感器，其特征在于， 所述每一 MTJ 元件组 (13) 的两侧设有一对第二永磁体 (14) ，各对第二永磁体 (14) 相对于对应的 MTJ 元件组 (13) 的敏感方向倾斜设置，用于消除所述 MTJ 元件组 (13) 的奈耳耦合场 。
12. 根据权利要求 10 所述的磁电阻齿轮传感器，其特征在于，各 对第二永磁体 (14) 相对于对应的 MTJ 元件组 (13) 的敏感方向倾斜设置，还用于消除所述 MTJ 元件组 (13) 的奈耳耦合场 。
13. 根据权利要求 7 或 8 所述的磁电阻齿轮传感器，其特征在于， 每一 MTJ 元件 (21) 为多层膜结构，包括依次沉积的钉扎层 (214) 、被钉扎层 (215) 、隧道势垒层 (216) 、磁性自由层 (217) 和偏置层 (218) 。
14. 根据权利要求 13 所述的磁电阻齿轮传感器，其特征在于， 每一 MTJ 元件 (21) 进一步包括设于所述磁性自由层 (217) 与所述偏置层 (218) 之间的隔离层。
15. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于，所述磁电阻齿轮传感器进一步包括 与 所述磁传感芯片 (181) 电连接 的控制电路 (183) 。
16. 根据权利要求 15 所述的磁电阻齿轮传感器，其特征在于， 所述控制电路（ 183 ）根据 所述磁传感芯片（181）输出的电压信号与齿轮轮齿位置点的对应关系来确定轮齿的位置。
17. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于，所述磁传感芯片包括双全桥，所述双全桥的每一桥臂包括 MTJ 元件组， 所述控制电路根据 所述磁传感芯片输出的电压信号来确定齿轮的运动方向。
18. 根据权利要求 1 所述的磁电阻齿轮传感器，其特征在于，所述磁电阻齿轮传感器进一步包括外壳 (185) 。
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