CN112578322A - Magnetic field sensing device - Google Patents

Abstract

The invention provides a magnetic field sensing device, comprising a plurality of magnetoresistive sensor groups with different average resistances, a first magnetization direction setting element and a second magnetization direction setting element. The number of these magnetoresistive sensor groups is four. A portion of the first group of magnetoresistive sensors is coupled to a portion of the second group of magnetoresistive sensors to form a first bridge arm. And the other part of the first magnetoresistive sensor group is coupled with the other part of the second magnetoresistive sensor group to form a second bridge arm. A portion of the third group of magnetoresistive sensors is coupled to a portion of the fourth group of magnetoresistive sensors to form a third bridge arm. And the other part of the third magnetoresistive sensor group is coupled with the other part of the fourth magnetoresistive sensor group to form a fourth bridge arm. The first to fourth bridge arms are coupled together to form a Wheatstone bridge. The first and second magnetization direction setting elements are respectively disposed to overlap two magnetoresistive sensor groups among the first to fourth magnetoresistive sensor groups.

Description

Magnetic field sensing device

Technical Field

The present invention relates to a magnetic field sensing device.

Background

With the development of science and technology, electronic products with navigation and positioning functions are becoming more and more diversified. Electronic compasses provide functionality comparable to conventional compasses in the fields of automotive navigation, aviation, and personal hand-held device applications. In order to realize the function of the electronic compass, the magnetic field sensing device becomes a necessary electronic component.

In a typical magnetic field sensing device, a Wheatstone bridge (Wheatstone bridge) is formed by magnetoresistive sensing elements, and an external magnetic field is measured by an output signal of a circuit. However, in the manufacturing process of the magnetoresistive sensing device, the magnetoresistive sensing devices in different areas have different resistances due to the manufacturing process factors (etching process, lift-off process, etc.), and the resistance difference is quite obvious, i.e. the resistance mismatch phenomenon. Resulting in the prior art magnetic field sensing device having a significant Zero-field Output offset before the external magnetic field has not been measured, resulting in inaccurate measurement results.

Disclosure of Invention

The invention provides a magnetic field sensing device which can effectively eliminate zero-field output offset and has accurate measurement results.

An embodiment of the present invention provides a magnetic field sensing apparatus, which includes a plurality of magnetoresistive sensor groups, a first magnetization direction setting element, and a second magnetization direction setting element. The average resistances of the magnetoresistive sensor groups are different from each other, and each magnetoresistive sensor group includes a plurality of magnetoresistive sensors. The magnetoresistive sensor groups include first to fourth magnetoresistive sensor groups. A portion of the first group of magnetoresistive sensors is coupled to a portion of the second group of magnetoresistive sensors to form a first bridge arm. And the other part of the first magnetoresistive sensor group is coupled with the other part of the second magnetoresistive sensor group to form a second bridge arm. And a part of the third magnetoresistive sensor group and a part of the fourth magnetoresistive sensor group are coupled to form a third bridge arm. And the other part of the third magnetoresistive sensor group and the other part of the fourth magnetoresistive sensor group are coupled to form a fourth bridge arm. The first to fourth bridge arms are coupled together in a Wheatstone bridge. The first magnetization direction setting element is provided to overlap with two magnetoresistive sensor groups among the first to fourth magnetoresistive sensor groups. And a second magnetization direction setting element provided so as to overlap with another two magnetoresistive sensor groups among the first to fourth magnetoresistive sensor groups.

In an embodiment of the present invention, in the first to fourth bridge arms, the line connection therein is an S-loop connection.

In an embodiment of the present invention, in the first to fourth bridge arms, the line connections therein are S-type line connections and straight line connections.

In an embodiment of the invention, the magnetic field sensing apparatus further includes a current generator. The current generator is used for generating current to the first magnetization direction setting element and the second magnetization direction setting element, wherein the current flow direction in the first magnetization direction setting element is opposite to the current flow direction in the second magnetization direction setting element.

In an embodiment of the invention, the first magnetization direction setting element and the first and second magnetoresistive sensor groups are disposed in an overlapping manner, and the second magnetization direction setting element and the third and fourth magnetoresistive sensor groups are disposed in an overlapping manner.

In an embodiment of the invention, the first magnetization direction setting element and the first and second magnetoresistive sensor groups are disposed in an overlapping manner, and the second magnetization direction setting element and the third and fourth magnetoresistive sensor groups are disposed in an overlapping manner.

In an embodiment of the invention, the first bridge arm and the second bridge arm are coupled to the first terminal. The second bridge arm and the fourth bridge arm are coupled with the second end point. The third bridge arm and the fourth bridge arm are coupled with the third end point. The fourth bridge arm is coupled to the first bridge arm and the fourth terminal. The first end point, the second end point, the third end point and the fourth end point are different from each other.

In an embodiment of the invention, an extending direction of each of the magnetoresistive sensors is perpendicular to extending directions of the first magnetization direction setting element and the second magnetization direction setting element.

In an embodiment of the invention, the magnetoresistive sensor is an anisotropic magnetoresistive sensor.

Based on the above, in the magnetic field sensing apparatus according to the embodiment of the invention, the magnetic field sensing apparatus has the first, second, third, and fourth magnetoresistive sensors with different average resistances, and the first, second, third, and fourth bridge arms of the wheatstone bridge are formed by cross-coupling the first to fourth magnetoresistive sensors, so that the relevant errors caused by the process factors can be dispersed in the bridge arms, thereby effectively eliminating the zero-field output offset and having an accurate measurement result. In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic diagram of a magnetic field sensing device according to an embodiment of the invention.

Fig. 2 is an effective circuit diagram of the magnetic field sensing device of fig. 1.

FIGS. 3A and 3B illustrate different layout methods of the anisotropic magnetoresistive sensor of FIG. 1.

FIG. 4 is a schematic diagram of a magnetic field sensing device according to another embodiment of the present invention.

Description of reference numerals: 100. 100 a: a magnetic field sensing device;

110: a magnetoresistive sensor group;

112: a first magnetoresistive sensor group;

114: a second magnetoresistive sensor group;

116: a third magnetoresistive sensor group;

118: a fourth magnetoresistive sensor group;

120: a first magnetization direction setting element;

130: a second magnetization direction setting element;

140: a current generator;

ARM1, ARM1 a: a first bridge arm;

ARM2, ARM2 a: a second bridge arm;

ARM3, ARM3 a: a third bridge arm;

ARM4, ARM4 a: a fourth bridge arm;

d: a direction of extension;

d1, D2: direction;

FF: a ferromagnetic film;

GND: a ground terminal;

h: an external magnetic field;

i: current flow;

m: a magnetization direction;

MR: a magnetoresistive sensor;

SB: a shorting bar;

SD: sensing a direction;

V_DD: a voltage supply terminal;

WHB: a wheatstone bridge.

Detailed Description

Fig. 1 is a schematic diagram of a magnetic field sensing device according to an embodiment of the invention. Fig. 2 is an effective circuit diagram of the magnetic field sensing device of fig. 1. FIGS. 3A and 3B illustrate different layout methods of the anisotropic magnetoresistive sensor of FIG. 1.

Referring to fig. 1, in the present embodiment, a magnetic field sensing apparatus 100 includes a plurality of magnetoresistive sensor groups 110, first and second magnetization direction setting elements 120 and 130, and a current generator 140. The above elements are described in detail in the following paragraphs.

In the present embodiment, each of the magnetoresistive sensor groups 110 includes a plurality of magnetoresistive sensors MR, and the extending direction of each of the magnetoresistive sensors MR is, for example, the direction D2. The number of the magnetoresistive sensor groups 110 is, for example, four, and is referred to as first, second, third, and fourth magnetoresistive sensor groups 112, 114, 116, and 118, respectively. The average resistances of the magnetoresistive sensor groups 110 in different regions are different from each other due to manufacturing process factors. In fig. 1, the magnetoresistive sensors MR belonging to the first to fourth magnetoresistive sensor groups 112, 114, 116, 118 are denoted by different cross sections.

In light of the above, the magnetoresistive sensor MR refers to a sensor whose resistance can be changed by a change in an external magnetic field. The magnetoresistive sensor MR may be an Anisotropic magnetoresistive sensor (AMR resistor). In the present embodiment, the extending direction of the magnetoresistive sensor MR is the direction D2. Referring to fig. 3A and 3B, the anisotropic magnetoresistive sensor MR has, for example, a barber pole (barber pole) structure, that is, a plurality of short-circuit bars (electrical short bars) SB extending at an angle of 45 degrees with respect to the extending direction D of the anisotropic magnetoresistive sensor MR are disposed on the surface of the anisotropic magnetoresistive sensor MR, the short-circuit bars SB are spaced apart from each other and are disposed in parallel on a ferromagnetic film (ferromagnetic film) FF, which is a main body of the anisotropic magnetoresistive sensor MR, and the extending direction of the ferromagnetic film FF is the extending direction of the anisotropic magnetoresistive sensor MR. The sensing direction SD of the anisotropic magnetoresistive sensor MR is perpendicular to the extension direction D. In addition, opposite ends of the ferromagnetic film FF may be made to be pointed (tapered).

In the present embodiment, the first and second magnetization direction setting elements 120 and 130 can be any one of a coil, a wire, a metal sheet, a conductor, or a combination thereof, which generates a magnetic field by being energized, and the extending direction of the first and second magnetization direction setting elements 120 and 130 is, for example, the direction D1, and the direction D1 is perpendicular to the direction D2.

In the present embodiment, the current generator 140 refers to an electronic device for providing current.

To illustrate the configuration effect of the magnetic field sensing device 100 of the present embodiment, the following paragraphs will be combined with fig. 3A and 3B to describe the basic principle of the magnetic field sensing device 100 of the present embodiment for measuring a magnetic field.

Referring to fig. 3A and 3B, before the anisotropic magnetoresistive sensor MR starts to measure the external magnetic field H, the magnetization direction thereof can be set by the first and second magnetization direction setting elements 120 and 130. In fig. 3A, the first and second magnetization direction setting elements 120 and 130 can generate a magnetic field along the extension direction D (or the long axis direction) by applying a current, so that the anisotropic magnetoresistive sensor MR has a magnetization direction M.

Then, the first and second magnetization direction setting elements 120 and 130 are not energized, so that the anisotropic magnetoresistive sensor MR starts to measure the external magnetic field H. When there is no external magnetic field H, the magnetization direction M of the anisotropic magnetoresistive sensor MR is maintained in the extension direction D, and the current generator 140 can apply the current I to flow from the left end to the right end of the anisotropic magnetoresistive sensor MR, so that the current I near the shorting bar SB flows perpendicular to the extension direction of the shorting bar SB, and the current I near the shorting bar SB flows at an angle of 45 degrees to the magnetization direction M, and the resistance value of the anisotropic magnetoresistive sensor MR is R.

When an external magnetic field H is oriented in a direction perpendicular to the extending direction D, the magnetization direction M of the anisotropic magnetoresistive sensor MR deflects outward in the direction of the magnetic field H, so that an included angle between the magnetization direction and the current I flowing direction near the shorting bar is greater than 45 degrees, and the resistance value of the anisotropic magnetoresistive sensor MR changes by- Δ R, i.e., becomes R- Δ R, that is, the resistance value becomes smaller, wherein Δ R is greater than 0.

However, as shown in fig. 3B, when the extending direction of the shorting bar SB in fig. 3B is located at an angle of 90 degrees with respect to the extending direction of the shorting bar SB in fig. 3A (at this time, the extending direction of the shorting bar SB in fig. 3B is still 45 degrees with respect to the extending direction D of the anisotropic magnetoresistive sensor MR), and when there is an external magnetic field H, the magnetization direction M is still deflected outward in the direction of the magnetic field H by the magnetic field H, and at this time, the angle between the magnetization direction M and the current I flowing direction near the shorting bar SB is smaller than 45 degrees, so the resistance value of the anisotropic magnetoresistive sensor MR becomes R + Δ R, that is, the resistance value of the anisotropic magnetoresistive sensor MR becomes larger.

When the magnetization direction M of the anisotropic magnetoresistive sensor MR is set to the reverse direction shown in fig. 3A by the first and second magnetization direction setting elements 120 and 130, the resistance value of the anisotropic magnetoresistive sensor MR shown in fig. 3A under the external magnetic field H becomes R + Δ R thereafter. When the magnetization direction M of the anisotropic magnetoresistive sensor MR is set to the reverse direction shown in fig. 3B by the magnetization direction setting element 130, the resistance value of the anisotropic magnetoresistive sensor MR in fig. 3B under the external magnetic field H becomes R- Δ R thereafter.

As described above, in the present embodiment, the resistance of the magnetoresistive sensor MR in the magnetoresistive sensor group 110 changes due to the external magnetic field, and the direction and magnitude of the external magnetic field can be determined by the differential signal at the voltage output terminal of the wheatstone bridge WHB. However, if the resistance values R of the MR sensors in different regions are too different due to process factors, the Wheatstone bridge WHB will have a significant zero-field output offset before the extraneous magnetic field is not measured. Therefore, at least one objective of the magnetic field sensing device 100 of the present embodiment is to solve the problem of zero-field output offset.

The following paragraphs will describe the configuration of the elements in the magnetic field sensing device 100 of the present embodiment in detail.

Referring to fig. 1, in the present embodiment, the first magnetization direction setting element 120 is disposed to overlap the first and second magnetoresistive sensor groups 112 and 114 and is disposed below the first and second magnetoresistive sensor groups 112 and 114. The second magnetization direction setting element 130 is disposed to overlap the third and fourth magnetoresistive sensor groups 116 and 118 and is disposed below the third and fourth magnetoresistive sensor groups 116 and 118. The current generator 140 is coupled to the first and second magnetization direction setting elements 120 and 130 through a conductive wire to form an S-shaped loop. When the current generator 140 generates the current I, the current I flows into the first and second magnetization direction setting elements 120 and 130 through the conducting wires, the current direction in the first magnetization direction setting element 120 is D1, and the current direction in the second magnetization direction setting element 130 is opposite to the direction D1, i.e. the current flows in the first and second magnetization direction setting elements 120 and 130 are anti-parallel (anti-parallel) to each other. Therefore, the first magnetization direction setting element 120 sets the magnetization direction M of the first and second magnetoresistive sensor groups 112 and 114 to the direction D2, for example, and the second magnetization direction setting element 130 sets the magnetization direction of the third and fourth magnetoresistive sensor groups 116 and 118 to the opposite direction of the direction D2, for example.

Referring to fig. 1, in detail, in the present embodiment, the magnetoresistive sensors MR of the first to fourth magnetoresistive sensor groups 112 to 118 having different average resistances are coupled to the first to fourth bridge ARMs ARM1 to ARM4 of the wheatstone bridge WHB in an inter-digital manner, so as to distribute the difference between the resistances to the respective bridge ARMs. The average resistance in the magnetoresistive sensor group 110 is: the arithmetic mean of the resistances of all the magnetoresistive sensors MR in the corresponding magnetoresistive sensor group 110. For example, in fig. 1 can be seen: the number of the magnetoresistive sensors MR in the first magnetoresistive sensor group 112 is three, and the average resistance of the first magnetoresistive sensor group 112 is the arithmetic average of the three magnetoresistive sensors MR (112) after the three magnetoresistive sensors MR (112) are summed up, and so on. The coupling of the bridge arms is described in detail in the following paragraphs.

In the present embodiment, the first bridge ARM1 is formed by coupling a part (one) of the first group of magnetoresistive sensors 112 and a part (two) of the second group of magnetoresistive sensors 114, for example.

Second bridge ARM2 is formed, for example, by coupling another portion (two) of first magnetoresistive sensor group 112 with another portion (one) of second magnetoresistive sensor group 114.

In the present embodiment, the third bridge ARM3 is formed by coupling a part (two) of the third group 116 of magnetoresistive sensors and a part (one) of the fourth group 118 of magnetoresistive sensors, for example.

Fourth bridge ARM4 is formed, for example, by coupling another portion (one) of third magnetoresistive sensor group 116 with a portion (two) of fourth magnetoresistive sensor group 118.

In view of the above, in the present embodiment, each of the bridge ARMs ARM 1-ARM 4 is formed by coupling the magnetoresistive sensors MR with the same magnetization direction. In the present embodiment, the wire connection in each of the bridge ARMs ARM 1-ARM 4 is an S-type connection. From another perspective, in each of the bridge ARMs ARM 1-ARM 4, the conductive lines between two MR sensors are bent conductive lines.

Referring to fig. 1 and fig. 2, in the magnetic field sensing device 100 of the present embodiment, the first and second bridge ARMs ARM1 and ARM2 are coupled to the first terminal P1. Second, and fourth bridge legs ARM2, ARM4 are coupled to second terminal P2. Third and fourth bridge legs ARM3 and ARM4 are coupled to third terminal P3. Fourth, first bridge ARM4, ARM1 is coupled to fourth terminal P4. The first to fourth terminals P1-P4 are different from each other, wherein the first terminal P1 is used as the voltage supply terminal V_DDThe second and fourth terminals P2 and P4 are, for example, voltage output terminals, and the third terminal P3 is, for example, a ground terminal GND, but the invention is not limited thereto.

In view of the above, the magnetic field sensing device 100 of the present embodiment includes the first to fourth magnetoresistive sensor groups 112, 114, 116 and 118 having different average resistances. The magnetic field sensing device 100 forms the first, second, third and fourth bridge ARMs ARM 1-ARM 4 of the wheatstone bridge WHB by cross-coupling the first to fourth magnetoresistive sensor groups 112, 114, 116, 118 with each other, so that the related errors caused by the process factors can be dispersed in the bridge ARMs ARM 1-ARM 4 by the coupling method, thereby effectively eliminating the zero-field output offset and having accurate measurement results.

It should be noted that, the following embodiments follow the contents of the foregoing embodiments, descriptions of the same technical contents are omitted, reference may be made to the contents of the foregoing embodiments for the same element names, and repeated descriptions of the following embodiments are omitted.

FIG. 4 is a schematic diagram of a magnetic field sensing device according to another embodiment of the present invention.

Referring to fig. 4, the magnetic field sensing device 100a of fig. 4 is substantially similar to the magnetic field sensing device 100 of fig. 1, and the main differences are: the differences in the installation relationship between the first and second magnetization direction setting elements 120 and 130 and the first to fourth magnetoresistive sensor groups 112, 114, 116 and 118, the numbers and properties of the magnetoresistive sensors in the first to fourth bridge ARMs ARM1a to ARM4a, and the wiring method are different, and the differences will be described in detail in the following paragraphs.

In the present embodiment, the first magnetization direction setting element 120 is disposed to overlap the first and fourth magnetoresistive sensor groups 112, 118 and is disposed under the first and fourth magnetoresistive sensor groups 112, 118, and the second magnetization direction setting element 130 is disposed to overlap the second and third magnetoresistive sensor groups 114, 116 and is disposed under the second and third magnetoresistive sensor groups 114, 116. Since the current I generated by the current generator 140 is in the direction opposite to the direction D1 and the direction D1 in the first and second magnetization direction setting elements 120 and 130, respectively, the magnetization direction M of the magnetoresistive sensors MR in the first and fourth magnetoresistive sensor groups 112 and 118 is set to the direction D2 by the first magnetization direction setting element 120, and the magnetization direction M of the magnetoresistive sensor MR in the second and third magnetoresistive sensor groups 114 and 116 is set to the direction opposite to the direction D2 by the second magnetization direction setting element 130.

In the present embodiment, the first bridge ARM1a is formed by coupling a part (three) of the first magnetoresistive sensor group 112 and a part (three) of the second magnetoresistive sensor group 114, for example.

In the present embodiment, the second bridge ARM2a is formed by coupling another part (three) of the first magnetoresistive sensor group 112 and another part (three) of the second magnetoresistive sensor group 114, for example.

In the present embodiment, the third bridge ARM3a is formed by coupling a part (three) of the third magnetoresistive sensor group 116 and a part (three) of the fourth magnetoresistive sensor group 118, for example.

In the present embodiment, the fourth bridge ARM4a is formed by coupling another part (three) of the third magnetoresistive sensor group 116 and another part (three) of the fourth magnetoresistive sensor group 118, for example.

It should be noted that, the equivalent circuit of the wheatstone bridge formed by the bridge ARMs ARM1 a-ARM 4a can also refer to the equivalent circuit of fig. 2, and the description thereof is similar to fig. 1, and is not repeated herein.

In view of the above, in the present embodiment, each of the bridge ARMs ARM1 a-ARM 4a is formed by coupling magnetoresistive sensors MR with different magnetization directions. The connection method in each of the bridge ARMs ARM1a to ARM4a is also slightly different. Specifically, in each of the bridge ARMs ARM1a to ARM4a, the wire bonding method between the partial magnetoresistive sensors MR is, for example, an S-type wire bonding method, and the wire bonding method between the other partial magnetoresistive sensors MR is, for example, a straight wire bonding method.

In summary, in the magnetic field sensing apparatus according to the embodiment of the invention, the magnetic field sensing apparatus has the first, second, third and fourth magnetoresistive sensors with different average resistances, and the first to fourth magnetoresistive sensors are cross-coupled to form the first, second, third and fourth bridge arms of the wheatstone bridge, so that the related errors caused by the process factors can be dispersed in the bridge arms by cross-coupling, thereby effectively eliminating the zero-field output offset and obtaining an accurate measurement result.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited thereto, and various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims (9)

1. A magnetic field sensing device, comprising:

a plurality of magnetoresistive sensor groups, average resistances of the plurality of magnetoresistive sensor groups being different from each other, and each of the magnetoresistive sensor groups including a plurality of magnetoresistive sensors, wherein the plurality of magnetoresistive sensor groups include first to fourth magnetoresistive sensor groups;

a part of the first magnetoresistive sensor group is coupled with a part of the second magnetoresistive sensor group to form a first bridge arm;

the other part of the first magnetoresistive sensor group is coupled with the other part of the second magnetoresistive sensor group to form a second bridge arm;

a part of the third magnetoresistive sensor group and a part of the fourth magnetoresistive sensor group are coupled to form a third bridge arm;

another part of the third magnetoresistive sensor group is coupled with another part of the fourth magnetoresistive sensor group to form a fourth bridge arm;

the first to the fourth bridge arms are coupled together in a Wheatstone bridge;

a first magnetization direction setting element provided to overlap with two magnetoresistive sensor groups among the first to fourth magnetoresistive sensor groups; and

and a second magnetization direction setting element provided so as to overlap with another two magnetoresistive sensor groups among the first to fourth magnetoresistive sensor groups.

2. The magnetic field sensing device according to claim 1, wherein in the first to the fourth bridge legs, the line connection therein is an S-loop connection.

3. The magnetic field sensing device according to claim 1, wherein in the first to the fourth bridge legs, the line connections therein are S-loop connections and straight connections.

4. The magnetic field sensing device according to claim 1, further comprising:

a current generator for generating a current to the first magnetization direction setting element and the second magnetization direction setting element,

wherein a flow direction of the current in the first magnetization direction setting element is opposite to a flow direction of the current in the second magnetization direction setting element.

5. The magnetic field sensing device according to claim 4, wherein the first magnetization direction setting element is disposed to overlap with the first group of magnetoresistive sensors and the second group of magnetoresistive sensors, and the second magnetization direction setting element is disposed to overlap with the third group of magnetoresistive sensors and the fourth group of magnetoresistive sensors.

6. The magnetic field sensing device according to claim 4, wherein the first magnetization direction setting element is disposed to overlap with the first group of magnetoresistive sensors and the second group of magnetoresistive sensors, and the second magnetization direction setting element is disposed to overlap with the third group of magnetoresistive sensors and the fourth group of magnetoresistive sensors.

7. The magnetic field sensing device according to claim 1, wherein,

the first bridge arm and the second bridge arm are coupled with a first end point;

the second bridge arm and the fourth bridge arm are coupled with a second end point;

the third bridge arm and the fourth bridge arm are coupled with a third end point; and

the fourth bridge leg is coupled to the first bridge leg and a fourth terminal,

wherein the first end point, the second end point, the third end point, and the fourth end point are different from each other.

8. The magnetic field sensing device according to claim 1, wherein an extension direction of each of the magnetoresistive sensors is perpendicular to an extension direction of the first magnetization direction setting element and the second magnetization direction setting element.

9. The magnetic field sensing device according to claim 1, wherein the kind of magnetoresistive sensor is an anisotropic magnetoresistive sensor.

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