CN115825826A - Three-axis full-bridge circuit transformation type linear magnetic field sensor - Google Patents
Three-axis full-bridge circuit transformation type linear magnetic field sensor Download PDFInfo
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Abstract
The invention relates to a three-axis full-bridge circuit conversion type linear magnetic field sensor which comprises two groups of magnetic field sensing units which are arranged perpendicular to each other, wherein each group of magnetic field sensing unit comprises a switch circuit and two magnetic field sensing array slices which are symmetrically arranged, the switch circuit is respectively connected with each magnetic field sensing array slice and is used for switching the conduction state between the two magnetic field sensing array slices to form a changeable bridge structure so as to obtain a three-axis push-pull type full-bridge magnetic field sensor, so that the magnetic field changes of an X axis, a Y axis and a Z axis can be measured, the magneto resistance shows obvious linear changes to an external magnetic field in the test process, meanwhile, the measurement error caused by the magnetic field in the direction of a non-sensitive axis can be eliminated, and the measurement precision is improved. In addition, the triaxial full-bridge circuit transformation type linear magnetic field sensor provided by the application adopts a magnetic field sensing array slicing structure, is simple in design and process, reduces the design and process difficulty, and is beneficial to improving the production efficiency and quality.
Description
Technical Field
The invention relates to the field of magnetic field sensors, in particular to a three-axis full-bridge circuit transformation type linear magnetic field sensor.
Background
The magnetoresistive sensor reflects an external magnetic field into an obvious low resistance state or a high resistance state by utilizing Tunneling magnetoresistive effect (TMR), anisotropic magnetoresistive effect (AMR) or Giant magnetoresistive effect (GMR), and the resistance value of the magnetoresistive sensor shows obvious linear change along with the change of the external magnetic field in a certain magnetic field range by introducing a proper structure. Compared with the traditional Hall magnetic field sensor, fluxgate sensor and the like, the magneto-resistance sensor has comprehensive advantages in the aspects of sensitivity and miniaturization, and is widely applied to the fields of integrated magnetic field and current sensing.
However, the magnetoresistive sensor based on TMR and GMR usually has only the single-axis linear sensitivity characteristic of the X-axis, the Y-axis or the Z-axis, and the signal of the single-axis sensing unit is interfered by the magnetic field in the non-sensitive axis direction, thereby causing a certain measurement error.
Disclosure of Invention
In view of the above, it is necessary to provide a three-axis full-bridge circuit transformation type linear magnetic field sensor.
The embodiment of the application provides a linear magnetic field sensor of triaxial full-bridge circuit transform formula, includes: the magnetic field sensing units are arranged vertically, each magnetic field sensing unit comprises a switch circuit and two magnetic field sensing array slices which are symmetrically arranged, and the switch circuit is connected with each magnetic field sensing array slice respectively and used for switching the conduction state between the two magnetic field sensing array slices; wherein each of the magnetic field sensing array slices comprises:
two magnetic field sensing arrays, each for sensing a magnetic field;
and the magnetic flux control module is positioned above each magnetic field sensing array.
In one embodiment, each of the magnetic field sensing arrays includes two magnetoresistive sensing element string structures disposed parallel to each other, and each of the magnetoresistive sensing element string structures includes at least one row of magnetoresistive sensing element strings electrically connected to each other.
In one embodiment, the series of magnetoresistive sensing elements comprises a plurality of interconnected magnetoresistive sensing elements.
In one embodiment, each of the magnetoresistive sensing elements is an elliptical or rectangular magnetoresistive sensing element, wherein a short axis direction of each of the magnetoresistive sensing elements is a magnetization direction of a pinning layer and is parallel to a short side direction of the magnetic flux control module, and a long axis direction of each of the magnetoresistive sensing elements is perpendicular to the magnetization direction of the pinning layer and is parallel to a long side direction of the magnetic flux control module.
In one embodiment, the magnetization direction of the magnetic free layer of each of the magnetoresistive sensor elements is parallel to the long axis direction of the magnetoresistive sensor element in the absence of an external magnetic field.
In one embodiment, the magnetic flux control modules are rectangular strip structures, the long side direction of each magnetic flux control module is perpendicular to the magnetization direction of a pinning layer of the magnetoresistive sensor element, the short side direction of each magnetic flux control module is parallel to the magnetization direction of the pinning layer of the magnetoresistive sensor element, each magnetic flux control module is arranged along the short side direction, and a gap is formed between every two adjacent magnetic flux control modules; and every two adjacent rows of the magnetoresistive sensing element strings are positioned below the magnetic flux control module and are arranged at equal intervals along the long side direction of the magnetic flux control module.
In one embodiment, each of the magnetic field sensing units comprises a first magnetic field sensing array slice and a second magnetic field sensing array slice; the first magnetic field sensing array slice comprises a first magnetic resistance sensing element string structure, a second magnetic resistance sensing element string structure, a third magnetic resistance sensing element string structure and a fourth magnetic resistance sensing element string structure; the second magnetic field sensing array slice comprises a fifth magnetoresistive sensing element string structure, a sixth magnetoresistive sensing element string structure, a seventh magnetoresistive sensing element string structure and an eighth magnetoresistive sensing element string structure; wherein,
the first magnetoresistive sensing element string structure and the fifth magnetoresistive sensing element string structure are centrosymmetric, the second magnetoresistive sensing element string structure and the sixth magnetoresistive sensing element string structure are centrosymmetric, the third magnetoresistive sensing element string structure and the seventh magnetoresistive sensing element string structure are centrosymmetric, and the fourth magnetoresistive sensing element string structure and the eighth magnetoresistive sensing element string structure are centrosymmetric.
In one embodiment, the switching circuit is controlled to connect the first end of the first magnetoresistance sense element string structure to the second end of the fifth magnetoresistance sense element string structure, connect the first end of the second magnetoresistance sense element string structure to the second end of the sixth magnetoresistance sense element string structure, connect the first end of the third magnetoresistance sense element string structure to the second end of the seventh magnetoresistance sense element string structure, connect the first end of the fourth magnetoresistance sense element string structure to the second end of the eighth magnetoresistance sense element string structure, connect the second end of the first magnetoresistance sense element string structure and the second end of the fourth magnetoresistance sense element string structure to a bias voltage, connect the second end of the second magnetoresistance sense element string structure and the second end of the third magnetoresistance sense element string structure to ground, connect the first end of the fifth magnetoresistance sense element string structure and the first end of the sixth magnetoresistance sense element string structure to form a first output end, connect the first end of the seventh magnetoresistance sense element string structure and the first end of the eighth magnetoresistance sense element string structure to form a second output end, and connect the first end of the seventh magnetoresistance sense element string structure and the eighth magnetoresistance sense element string structure to form a second output end.
In one embodiment, the switching circuit is controlled to connect the first end of the first magnetoresistance sense element string structure with the first end of the second magnetoresistance sense element string structure, the second end of the fifth magnetoresistance sense element string structure with the second end of the sixth magnetoresistance sense element string structure, the second end of the third magnetoresistance sense element string structure with the second end of the fourth magnetoresistance sense element string structure, the first end of the seventh magnetoresistance sense element string structure with the first end of the eighth magnetoresistance sense element string structure, the second end of the first magnetoresistance sense element string structure and the second end of the seventh magnetoresistance sense element string structure both connected with a bias voltage, the first end of the third magnetoresistance sense element string structure and the first end of the fifth magnetoresistance sense element string structure both grounded, the second end of the second magnetoresistance sense element string structure and the first end of the sixth magnetoresistance sense element string structure connected and serving as a first output terminal, the first end of the fourth magnetoresistance sense element string structure and the second end of the eighth magnetoresistance sense element string structure connected and serving as a second output terminal, and the magnetic field measurement device is used for measuring a magnetic field in an X-axis or a Y-axis direction.
In one embodiment, an output voltage V = (R1-R2) Vbias/(R1 + R2) between the first output and the second output; wherein R1 represents an equivalent resistance of the first magnetoresistive sensing element string structure or the third magnetoresistive sensing element string structure, R2 represents an equivalent resistance of the second magnetoresistive sensing element string structure or the fourth magnetoresistive sensing element string structure, and Vbias represents the bias voltage.
The three-axis full-bridge circuit transformation type linear magnetic field sensor provided by the embodiment comprises two groups of magnetic field sensing units which are perpendicular to each other, each group of magnetic field sensing unit comprises a switch circuit and two magnetic field sensing array slices which are symmetrically arranged, the switch circuit is respectively connected with each magnetic field sensing array slice and is used for switching the conduction state between the two magnetic field sensing array slices to form a changeable bridge structure, so that the three-axis push-pull type full-bridge magnetic field sensor is obtained, the magnetic field changes of an X axis, a Y axis and a Z axis can be measured, the magneto resistance presents obvious linear changes to an external magnetic field in the test process, meanwhile, the measurement error caused by the magnetic field in the direction of a non-sensitive axis can be eliminated, and the measurement precision is improved. In addition, the triaxial full-bridge circuit transformation type linear magnetic field sensor provided by the application adopts a magnetic field sensing array slicing structure, is simple in design and process, reduces the design and process difficulty, and is beneficial to improving the production efficiency and quality.
Drawings
Fig. 1 is a schematic structural diagram of a three-axis full-bridge circuit transformation type linear magnetic field sensor according to an embodiment;
FIG. 2 is a schematic diagram of a magnetic field sensing array according to an embodiment;
FIG. 3 is a schematic structural diagram of a magnetic field sensing unit according to an embodiment;
fig. 4 is a schematic structural diagram of a three-axis full-bridge circuit transformation type linear magnetic field sensor according to another embodiment;
FIG. 5 is a schematic diagram of a switch circuit according to an embodiment;
FIG. 6 is a schematic diagram illustrating a circuit connection relationship of a magnetic field sensing unit according to an embodiment;
FIG. 7 is an equivalent circuit diagram of the circuit shown in FIG. 6 according to one embodiment;
FIG. 8 is a schematic diagram of magnetic fields around a magnetoresistive sensing element according to one embodiment;
FIG. 9 is a schematic diagram illustrating resistance versus magnetic field of a magnetoresistive sensing element according to one embodiment;
FIG. 10 is a schematic diagram illustrating a circuit connection relationship of a magnetic field sensing unit according to another embodiment;
FIG. 11 is an equivalent circuit diagram for the circuit of FIG. 10 according to one embodiment;
FIG. 12 is a schematic diagram of magnetic fields around a magnetoresistive sensing element according to another embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
As the background art shows, in order to realize three-axis detection and improve the measurement accuracy, the application provides a three-axis full-bridge circuit transformation type linear magnetic field sensor.
In one embodiment, referring to fig. 1, a three-axis full-bridge circuit transformation type linear magnetic field sensor is provided. The three-axis full-bridge circuit conversion type linear magnetic field sensor comprises two groups of magnetic field sensing units 10 which are arranged vertically. Illustratively, one set of magnetic field sensing units 10 may be rotated 90 degrees in the X-Y plane to provide another set of magnetic field sensing units 10. Each set of magnetic field sensing units 10 comprises a switching circuit 110 and two symmetrically arranged magnetic field sensing array slices 120. The switch circuit 110 is connected to each magnetic field sensing array slice 120, and the switch circuit 110 is configured to switch a conducting state between two magnetic field sensing array slices 120. Each magnetic field sensing array slice 120 has the same structure, and includes two magnetic field sensing arrays 121 and a magnetic flux control module 122. Each magnetic field sensing array 121 is for sensing a magnetic field. The magnetic flux control module 122 is located above each magnetic field sensing array 121, the magnetic flux control module 122 may be used to adjust the direction and magnitude of the magnetic field, and the magnetic flux control module 122 may be a magnetic flux controller. Illustratively, each magnetic field sensing array slice 120 may further include a substrate 123, and each magnetic field sensing array 121 may be deposited on the substrate 123. Illustratively, the substrate 123 may be a silicon single crystal substrate or other common electronic component substrate.
According to the triaxial full-bridge circuit conversion type linear magnetic field sensor, the switching circuit is used for switching the conduction state between the two magnetic field sensing array slices to form a changeable bridge structure, the triaxial push-pull type full-bridge magnetic field sensor is obtained, the magnetic field changes of an X axis, a Y axis and an out-of-plane Z axis in a plane can be measured, so that the external magnetic field presents obvious linear change in the test process, meanwhile, the measurement error caused by the magnetic field in the direction of a non-sensitive axis can be eliminated, and the measurement precision is improved. In addition, the triaxial full-bridge circuit transformation type linear magnetic field sensor adopts a magnetic field sensing array slicing structure, the design and the process are simple, the design and the process difficulty are reduced, and the production efficiency and the quality are favorably improved.
In one embodiment, referring to fig. 2, each magnetic field sensing array 121 includes two magnetoresistive sensing element string structures 1210 disposed parallel to each other, wherein two ends of one magnetoresistive sensing element string structure 1210 are electrically connected to a pad 11 and a pad 13, respectively, and two ends of the other magnetoresistive sensing element string structure 1210 are electrically connected to a pad 12 and a pad 14, respectively. Each magnetoresistive sensing element string structure 1210 includes at least one row of magnetoresistive sensing element strings 1211 electrically connected to each other, and each row of magnetoresistive sensing element strings 1211 is arranged in the Y-axis direction in fig. 2.
The three-axis full-bridge circuit conversion type linear magnetic field sensor has the advantages that each magnetic field sensing array 121 is composed of at least one row of magnetic resistance sensing element strings 1211 which are electrically connected with each other, a changeable bridge structure is formed by combining the switch circuit 110, the three-axis push-pull type full-bridge magnetic field sensor is obtained, the magnetic field changes of an in-plane X axis, a Y axis and an out-plane Z axis can be measured, the magnetic resistance presents obvious linear changes to an external magnetic field in the test process, meanwhile, the measurement error caused by the magnetic field in the direction of a non-sensitive axis can be eliminated, the measurement precision is improved, the design and the process are simple, and the production efficiency and the quality are improved.
In one embodiment, with continued reference to FIG. 2, each magnetoresistive sensing element string 1211 may include a plurality of interconnected magnetoresistive sensing elements 1211a. Each magnetoresistive sensing element string 1211 may also include one magnetoresistive sensing element 1211a. Illustratively, each magnetoresistive sensing element 1211a may be a TMR magnetoresistive sensing element or a GMR magnetoresistive sensing element.
Each magnetoresistive sensing element string 1211 is composed of one or more magnetoresistive sensing elements 1211a which are mutually and electrically connected, a changeable bridge structure is formed by combining the switch circuit 110, and the triaxial push-pull type full-bridge magnetic field sensor is obtained, so that the magnetic field changes of an X axis, a Y axis and an out-of-plane Z axis in a plane can be measured, the magnetoresistance presents obvious linear change to an external magnetic field in the test process, meanwhile, the measurement error caused by the magnetic field in the direction of a non-sensitive axis can be eliminated, the measurement precision is improved, the design and the process are simple, and the production efficiency and the quality are favorably improved.
In one embodiment, each magnetoresistive sensing element 1211a may be an elliptical or rectangular magnetoresistive sensing element, with the magnetoresistive sensing elements 1211a shown in FIG. 2 being elliptical. The short axis direction of each magnetoresistive sensor element 1211a is the magnetization direction of the pinned layer and is parallel to the short side direction of the magnetic flux control block 122, and the long axis direction of each magnetoresistive sensor element 1211a is perpendicular to the magnetization direction of the pinned layer and is parallel to the long side direction of the magnetic flux control block 122.
In the three-axis full-bridge circuit conversion type linear magnetic field sensor, each of the magnetic resistance sensing elements 1211a may be an ellipse or a rectangle, so as to increase the design diversity and the realizability, and the position direction of each of the magnetic resistance sensing elements 1211a is set to realize sensing of the three-axis magnetic field variation.
In one embodiment, each magnetoresistive sensing element 1211a includes a magnetic tunnel junction multilayer film structure. The magnetic tunnel junction multilayer thin film structure may include an antiferromagnetic layer, a pinned layer, a ferromagnetic reference layer, a metal spacer layer, a ferromagnetic reference layer, an insulating tunneling layer, and a ferromagnetic free layer, or the antiferromagnetic layer, the pinned layer, the ferromagnetic reference layer, the metal spacer layer, the ferromagnetic reference layer, a nonmagnetic metal layer, and the ferromagnetic free layer, from top to bottom.
The three-axis full-bridge circuit transformation type linear magnetic field sensor, each magnetoresistive sensing element 1211a has a magnetic tunnel junction multilayer film structure, thereby realizing sensing of a three-axis magnetic field variation.
In one embodiment, the magnetization direction of the magnetic free layer of each magnetoresistive sensor element 1211a is parallel to the long axis direction of the magnetoresistive sensor element 1211a in the absence of an external magnetic field, so as to sense magnetic fields in different directions. Illustratively, the magnetoresistive sensing cell 10 may be annealed at the blocking temperature of the antiferromagnetic layer to make the pinning direction of the reference layer parallel to the short axis direction of the magnetoresistive sensing element 1211a by applying a magnetic field in the short axis direction of the magnetoresistive sensing element 1211a during cooling.
In one embodiment, with continued reference to fig. 2, the magnetic flux control modules 122 may have a rectangular strip structure, the long side direction of the magnetic flux control module 122 is perpendicular to the magnetization direction of the pinned layer of the magnetoresistive sensor element 1211a, the short side direction of the magnetic flux control module 122 is parallel to the magnetization direction of the pinned layer of the magnetoresistive sensor element 1211a, each of the magnetic flux control modules 122 is arranged along the short side direction, and a gap is formed between two adjacent magnetic flux control modules 122. Here, every two adjacent rows of magnetoresistive sensing element strings 1211 are positioned below the magnetic flux control module 122 and arranged at equal intervals in the longitudinal direction of the magnetic flux control module 122. In one embodiment, the material of the rectangular strip structure of the magnetic flux control module 122 is a soft ferromagnetic alloy.
In the three-axis full-bridge circuit conversion type linear magnetic field sensor, the magnetic flux control module 122 is set to be in a rectangular strip structure, and covers the upper part of the magnetoresistive sensing element 1211 so as to adjust the direction and the size of the magnetic field, so that the magnetic field can be sensed by the magnetoresistive sensing element 1211a, and the three-axis magnetic field can be measured.
For a better understanding, referring to FIG. 3 in conjunction with the magnetic field sensing array 121 shown in FIG. 2, a single magnetic field sensing array slice 120 is illustrated. As shown in FIG. 3, the magnetic field sensing array slice 120 includes a substrate 123, two magnetic field sensing arrays 121 deposited on the substrate 123, a flux control module 122, and 8 pads 11-18. The specific structure of the magnetic field sensing array 121 can be seen in fig. 2 and related contents, which are not described herein again.
In one embodiment, referring to fig. 4, an example of a magnetoresistive sensing element string structure including three rows of magnetoresistive sensing element strings and a magnetoresistive sensing element string including eight oval magnetoresistive sensing elements is illustrated. Each magnetic field sensing unit includes a first magnetic field sensing array slice and a second magnetic field sensing array slice. The first magnetic field sensing array slice comprises a first magnetic resistance sensing element string structure, a second magnetic resistance sensing element string structure, a third magnetic resistance sensing element string structure and a fourth magnetic resistance sensing element string structure. The second magnetic field sensing array slice includes a fifth magnetoresistive sensing element string structure, a sixth magnetoresistive sensing element string structure, a seventh magnetoresistive sensing element string structure, and an eighth magnetoresistive sensing element string structure.
Wherein, two ends of the first magnetoresistive sensing element string structure are respectively connected with the bonding pad 16 and the bonding pad 18; two ends of the second magnetoresistive sensing element string structure are respectively connected with the bonding pad 15 and the bonding pad 17; two ends of the third magnetoresistive sensing element string structure are respectively connected with the bonding pad 12 and the bonding pad 14; two ends of the fourth magnetic resistance sensing element string structure are respectively connected with the bonding pad 11 and the bonding pad 13; two ends of the fifth magnetoresistive sensing element string structure are respectively connected with the bonding pad 16 'and the bonding pad 18'; two ends of the sixth magnetoresistive sensing element string structure are respectively connected with the bonding pad 15 'and the bonding pad 17'; two ends of the seventh magnetoresistive sensing element string structure are respectively connected with the bonding pad 12 'and the bonding pad 14'; the two ends of the eighth magnetoresistance sensing element string structure are connected to the pads 11 'and 13', respectively.
The first magnetoresistive sensing element string structure and the fifth magnetoresistive sensing element string structure are centrosymmetric, the second magnetoresistive sensing element string structure and the sixth magnetoresistive sensing element string structure are centrosymmetric, the third magnetoresistive sensing element string structure and the seventh magnetoresistive sensing element string structure are centrosymmetric, and the fourth magnetoresistive sensing element string structure and the eighth magnetoresistive sensing element string structure are centrosymmetric.
In one embodiment, please continue to refer to fig. 4 with reference to fig. 5 and 6. Fig. 5 shows the switch circuit 110, the pads shown in fig. 5 are connected to the pads shown in fig. 4 in a one-to-one correspondence, and the switch circuit may include 16 MOS transistors, a bias voltage supply input terminal VDD, a ground terminal GND, an output V1 terminal, an output V2 terminal, and level control S1 and S2 terminals. Fig. 6 is a diagram showing the electrical connections between two slices of the magnetic field sensing array in the magnetic field sensing unit of fig. 4.
Specifically, the switching circuit may be controlled to connect a first end of the first magnetoresistive sensing element string structure (i.e., pad 16) to a second end of the fifth magnetoresistive sensing element string structure (i.e., pad 18'), i.e., to connect pad 26 and pad 36; connecting a first end of the second magnetoresistive sensing element string structure (i.e., pad 15) to a second end of the sixth magnetoresistive sensing element string structure (i.e., pad 17'), i.e., connecting pad 25 and pad 35; connecting a first end (i.e., pad 12) of the third magnetoresistive sensing element string structure to a second end (i.e., pad 14') of the seventh magnetoresistive sensing element string structure, i.e., connecting pad 22 and pad 32; connecting a first end (i.e., pad 11) of the fourth magnetoresistive sensing element string structure to a second end (i.e., pad 13') of the eighth magnetoresistive sensing element string structure, i.e., connecting pad 21 and pad 31; connecting both the second end of the first series of magnetoresistive sensing elements (i.e., pad 18) and the second end of the fourth series of magnetoresistive sensing elements (i.e., pad 23) to a bias voltage Vbias, i.e., pad 27 to pad 24; grounding both the second end of the second magnetoresistive sensing element string structure (i.e., pad 17) and the second end of the third magnetoresistive sensing element string structure (i.e., pad 14), i.e., pads 28 and 23 to GND; connecting a first end of the fifth magnetoresistive sensing element string structure (i.e., pad 16 ') and a first end of the sixth magnetoresistive sensing element string structure (i.e., pad 15') and being a first output terminal V1, i.e., pad 37 is connected to pad 38 and being a first output terminal V1; a first end (i.e., the pad 12 ') of the seventh magnetoresistive sensing element string structure and a first end (i.e., the pad 11') of the eighth magnetoresistive sensing element string structure are connected and are a second output terminal V2, i.e., the pad 33 is connected to the pad 34 and is a second output terminal V2, to measure the Z-axis direction magnetic field.
Fig. 4 is an equivalent circuit shown in fig. 7, in which the first magnetoresistance sensing element string structure and the fifth magnetoresistance sensing element string structure form a first push arm, the second magnetoresistance sensing element string structure and the sixth magnetoresistance sensing element string structure form a first pull arm, the third magnetoresistance sensing element string structure and the seventh magnetoresistance sensing element string structure form a second push arm, and the fourth magnetoresistance sensing element string structure and the eighth magnetoresistance sensing element string structure form a second pull arm.
When the external magnetic field direction is the Z direction, the magnetic flux control module regulates and controls the magnetic field direction and magnitude, the magnetic field around the magnetoresistive sensing element is as shown in fig. 8, and the arrow direction in the figure is the magnetic induction line direction. The magnetic fields actually induced by the magnetoresistive sensing element strings positioned on two sides below the same magnetic flux control module respectively form a push arm and a pull arm along the + X direction and the-X direction, the magnetoresistive sensors in the push arm are in a high resistance state R1, and the magnetoresistive sensors in the pull arm are in a low resistance state R2. Ideally, the output voltage of the push-pull full bridge shown in fig. 7 is:
wherein V represents an output voltage between the first output terminal and the second output terminal; v1 represents a first output terminal; v2 represents a second output terminal; vbias represents a bias voltage; r1 represents the equivalent resistance of the first push arm or the second push arm; r2 represents an equivalent resistance of the first or second lever arm.
When a magnetic field in the X-axis direction exists, an interference magnetic field in the X-axis direction may exist in the space, causing the resistances R1 and R2 corresponding to the push arm and the pull arm to decrease or increase by Δ R, as shown in fig. 9, where the abscissa H represents the magnetic field, the ordinate R represents the resistance, B1 represents the negative saturation magnetic field, B2 represents the positive saturation magnetic field, RL represents the minimum resistance of the magnetic tunnel junction when the magnetic field is parallel to the pinning direction of the pinning layer, and RH represents the maximum resistance of the magnetic tunnel junction when the magnetic field is perpendicular to the pinning direction of the pinning layer.
If the magnetic field is opposite to the magnetization direction of the pinning layer of the left magnetoresistive sensor, the magnetoresistance in the first push arm is R1+ delta R, and the magnetoresistance in the first pull arm is R2+ delta R; the magnetization direction of the pinned layer of the right magnetoresistive sensor is the same, the magnetoresistance in the second push arm is R1-DeltaR, and the magnetoresistance in the second pull arm is R2-DeltaR. At this time, the output voltage of the push-pull full bridge is:
if the magnetic field is the same as the magnetization direction of the pinning layer of the left magnetoresistive sensor, the magnetoresistance in the first push arm is R1-Delta R, and the magnetoresistance in the first pull arm is R2-Delta R; the magnetization direction of the pinning layer of the right magnetoresistive sensor is opposite, the magnetoresistance in the second push arm is R1+ DeltaR, and the magnetoresistance in the second pull arm is R2+ DeltaR. The output voltage of the push-pull full bridge is as follows:
the voltage output value is the same as the voltage output when only the magnetic field in the z-axis direction exists, and no in-plane direction error exists, so that the push-pull type full-bridge magnetic field sensor provided by the application can eliminate the error caused by the in-plane magnetic field when the out-of-plane magnetic field is tested.
In one embodiment, with continuing reference to fig. 4 and 5 and with further reference to fig. 10, the switching circuit is controlled to connect the first end of the first series of magnetoresistive sensing elements (i.e., pad 16) to the first end of the second series of magnetoresistive sensing elements (i.e., pad 15), i.e., to connect pad 26 to pad 25; connecting a second end of the fifth magneto-resistive sensing element string structure (i.e., pad 18 ') to a second end of the sixth magneto-resistive sensing element string structure (i.e., pad 17'), i.e., connecting pad 36 to pad 35; connecting a second end (i.e., pad 14) of the third magnetoresistive sensing element string structure to a second end (i.e., pad 13) of the fourth magnetoresistive sensing element string structure, i.e., connecting pad 23 to pad 24; connecting a first end (i.e., pad 12 ') of the seventh magnetoresistive sensing element string structure to a first end (i.e., pad 11') of the eighth magnetoresistive sensing element string structure, i.e., connecting pad 33 to pad 34; connecting both the second end of the first magnetoresistive sensing element string structure (i.e., pad 18) and the second end of the seventh magnetoresistive sensing element string structure (i.e., pad 14') to the bias voltage Vbias, i.e., connecting pad 27 to pad 32; grounding both the first end of the third magnetoresistive sensing element string structure (i.e., pad 12) and the first end of the fifth magnetoresistive sensing element string structure (i.e., pad 16'), i.e., both pad 22 and pad 37 are grounded to GND; connecting the second end of the second magneto-resistive sensing element string structure (i.e., pad 17) and the first end of the sixth magneto-resistive sensing element string structure (i.e., pad 15') and being a first output terminal V1, i.e., pad 28 is connected to pad 38 and being a first output terminal V1; a first end (i.e., the pad 11) of the fourth magnetoresistance sense element string structure and a second end (i.e., the pad 13') of the eighth magnetoresistance sense element string structure are connected and are the second output terminal V2, i.e., the pad 21 is connected to the pad 31 and is the second output terminal V2, to measure the X-axis or Y-axis direction magnetic field.
Fig. 4 is an equivalent circuit shown in fig. 11, in which the first magnetoresistance sensor element string structure and the second magnetoresistance sensor element string structure form a first push arm, the fifth magnetoresistance sensor element string structure and the sixth magnetoresistance sensor element string structure form a first pull arm, the third magnetoresistance sensor element string structure and the fourth magnetoresistance sensor element string structure form a second push arm, and the seventh magnetoresistance sensor element string structure and the eighth magnetoresistance sensor element string structure form a second pull arm.
When the external magnetic field direction is the X direction, the magnetic field around the magnetoresistive sensing element is as shown in fig. 12, and ideally, the output voltage of the push-pull full bridge is:
when an additional magnetic field in the Z-axis direction exists, the magnetoresistance of two rows of magnetoresistive sensing element strings in the first push arm and the second push arm are respectively R1-delta R and R1+ delta R, and the magnetoresistance of two rows of magnetoresistive sensing element strings in the first pull arm and the second pull arm are respectively R2-delta R and R2+ delta R. At this time, the output voltage of the push-pull full bridge is:
the voltage output value is the same as that of the voltage output when only the magnetic field in the X-axis direction exists, and other direction errors do not exist.
When the external magnetic field direction is the Y direction, ideally, the push-pull full bridge outputs voltage as follows:
when an additional magnetic field in the Z-axis direction exists, the magnetoresistance of the two rows of the magnetoresistive sensing element strings in the first push arm and the second push arm are respectively R1-delta R-delta Rz and R1+ delta R + delta Rz, and the magnetoresistance of the two rows of the magnetoresistive sensing element strings in the first pull arm and the second pull arm are respectively R2-delta R-delta Rz and R2+ delta R + delta Rz. At this time, the output voltage of the push-pull full bridge is:
the voltage output value is the same as that of the voltage output when only the magnetic field in the Y-axis direction exists, and other direction errors do not exist.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A three-axis full-bridge circuit transformation type linear magnetic field sensor is characterized by comprising: the magnetic field sensing units are arranged vertically, each magnetic field sensing unit comprises a switch circuit and two magnetic field sensing array slices which are symmetrically arranged, and the switch circuit is connected with each magnetic field sensing array slice respectively and used for switching the conduction state between the two magnetic field sensing array slices; wherein each of the magnetic field sensing array slices comprises:
two magnetic field sensing arrays, each for sensing a magnetic field;
and the magnetic flux control module is positioned above each magnetic field sensing array.
2. The three-axis full-bridge switched linear magnetic field sensor according to claim 1, wherein each of the magnetic field sensing arrays comprises two magnetoresistive sensing element string structures disposed parallel to each other, each of the magnetoresistive sensing element string structures comprising at least one row of magnetoresistive sensing element strings electrically connected to each other.
3. The tri-axial full bridge switched linear magnetic field sensor according to claim 2, wherein the series of magnetoresistive sensing elements comprises a plurality of interconnected magnetoresistive sensing elements.
4. The sensor according to claim 3, wherein each of the magnetoresistive sensing elements is an elliptical or rectangular magnetoresistive sensing element, wherein a short axis direction of each of the magnetoresistive sensing elements is a magnetization direction of a pinning layer and is parallel to a short side direction of the magnetic flux control module, and a long axis direction of each of the magnetoresistive sensing elements is perpendicular to the magnetization direction of the pinning layer and is parallel to a long side direction of the magnetic flux control module.
5. The sensor according to claim 4, wherein the magnetization direction of the free magnetic layer of each of the magnetoresistive sensor elements is parallel to the long axis of the magnetoresistive sensor elements in the absence of an external magnetic field.
6. The sensor according to claim 2, wherein the flux control modules are rectangular strips, the long side direction of the flux control modules is perpendicular to the magnetization direction of the pinned layer of the magnetoresistive sensor element, the short side direction of the flux control modules is parallel to the magnetization direction of the pinned layer of the magnetoresistive sensor element, each of the flux control modules is arranged along the short side direction, and a gap is formed between two adjacent flux control modules; wherein,
every two adjacent rows of the magnetoresistive sensing element strings are positioned below the magnetic flux control module and are arranged at equal intervals along the long edge direction of the magnetic flux control module.
7. The three-axis full-bridge switched linear magnetic field sensor according to claim 1, wherein each of the magnetic field sensing units comprises a first magnetic field sensing array slice and a second magnetic field sensing array slice; the first magnetic field sensing array slice comprises a first magnetic resistance sensing element string structure, a second magnetic resistance sensing element string structure, a third magnetic resistance sensing element string structure and a fourth magnetic resistance sensing element string structure; the second magnetic field sensing array slice comprises a fifth magnetoresistive sensing element string structure, a sixth magnetoresistive sensing element string structure, a seventh magnetoresistive sensing element string structure and an eighth magnetoresistive sensing element string structure; wherein,
the first magnetoresistive sensing element string structure and the fifth magnetoresistive sensing element string structure are centrosymmetric, the second magnetoresistive sensing element string structure and the sixth magnetoresistive sensing element string structure are centrosymmetric, the third magnetoresistive sensing element string structure and the seventh magnetoresistive sensing element string structure are centrosymmetric, and the fourth magnetoresistive sensing element string structure and the eighth magnetoresistive sensing element string structure are centrosymmetric.
8. The tri-axial full bridge switched linear magnetic field sensor of claim 7, wherein the switching circuit is controlled to connect the first end of the first series of magneto-resistive sensing elements to the second end of the fifth series of magneto-resistive sensing elements, the first end of the second series of magneto-resistive sensing elements to the second end of the sixth series of magneto-resistive sensing elements, the first end of the third series of magneto-resistive sensing elements to the second end of the seventh series of magneto-resistive sensing elements, the first end of the fourth series of magneto-resistive sensing elements to the second end of the eighth series of magneto-resistive sensing elements, the second end of first magnetic resistance sensing element string structure with the second end of fourth magnetic resistance sensing element string structure all is connected with bias voltage, the second end of second magnetic resistance sensing element string structure with the second end of third magnetic resistance sensing element string structure all is ground connection, the first end of fifth magnetic resistance sensing element string structure with the first end of sixth magnetic resistance sensing element string structure is connected and is first output, the first end of seventh magnetic resistance sensing element string structure with the first end of eighth magnetic resistance sensing element string structure is connected and is the second output to measure Z axle direction magnetic field.
9. The tri-axial full bridge switched linear magnetic field sensor according to claim 7, wherein the switch circuit is controlled to connect the first end of the first series structure of magnetoresistive sensing elements to the first end of the second series structure of magnetoresistive sensing elements, the second end of the fifth series structure of magnetoresistive sensing elements to the second end of the sixth series structure of magnetoresistive sensing elements, the second end of the third series structure of magnetoresistive sensing elements to the second end of the fourth series structure of magnetoresistive sensing elements, the first end of the seventh series structure of magnetoresistive sensing elements to the first end of the eighth series structure of magnetoresistive sensing elements, the second end of the first series structure of magnetoresistive sensing elements and the second end of the seventh series structure of magnetoresistive sensing elements both connected to a bias voltage, the first end of the third series structure of magnetoresistive sensing elements and the first end of the fifth series structure of magnetoresistive sensing elements both connected to ground, the second end of the second series structure of magnetoresistive sensing elements and the first end of the sixth series structure of magnetoresistive sensing elements both connected to a first output terminal, the second end of the fourth series structure of magnetoresistive sensing elements and the first end of the sixth series structure of magnetoresistive sensing elements both connected to a first output terminal, and the second series structure of magnetoresistive sensing elements connected to the second end of the second series structure of magnetoresistive sensing elements and the second sense element or the second magnetoresistive sensing element connected to the second sense element and the second end of the second magnetoresistive sensing element connected to the second magnetoresistive sensing element or the second magnetoresistive sensing element string structure.
10. The three-axis full-bridge switched linear magnetic field sensor according to claim 8 or 9, wherein an output voltage V = (R1-R2) Vbias/(R1 + R2) between the first output terminal and the second output terminal; wherein R1 represents an equivalent resistance of the first magnetoresistive sensing element string structure or the third magnetoresistive sensing element string structure, R2 represents an equivalent resistance of the second magnetoresistive sensing element string structure or the fourth magnetoresistive sensing element string structure, and Vbias represents the bias voltage.
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