TW201719189A - Magnetic field sensing apparatus and detection method thereof - Google Patents

Abstract

A magnetic field sensing apparatus and a detection method thereof are provided. The magnetic field sensing apparatus includes a first anisotropic magneto-resistive (AMR) resistor, a second AMR resistor, a current generator and an arithmetic device. A magnetized direction of the first AMR resistor is set to a first direction, and a magnetized direction of the second AMR resistor is set to a second direction, wherein the first direction is opposite to or the same as the second direction. The current generator provides current to flow through the first and second AMR resistors along a direction parallel to the first direction. The arithmetic device obtains a first detection voltage according to a voltage difference between two ends of the first AMR resistor, obtains a second detection voltage according to a voltage difference between two ends of the second AMR resistor, and operates an arithmetic operation on the first and second detection voltages to obtain a first magnetic field detection result.

Description

Magnetic field sensing device and sensing method thereof

The present invention relates to a magnetic field sensing device and a sensing method, and more particularly to a magnetic field sensing device and a sensing method using an anisotropic magnetoresistance.

With the popularity of portable electronic devices, the technology of an electronic compass capable of sensing the geomagnetic direction has received attention. When an electronic compass is applied to a small portable electronic device (such as a smart phone), in addition to the small volume requirement, the electronic compass is preferably capable of achieving three-axis sensing because the user When holding the phone in your hand, it may be held obliquely, and various holding angles may also occur. In addition, the electronic compass can also be applied to drones (such as remote control aircraft, remote control helicopters, etc.).

In the prior art, an anisotropic magneto-resistive resistor (AMR resistor) is commonly used and a magnetic field sensing operation is performed through a Wheatstone bridge architecture. In the Wheatstone full bridge architecture, four anisotropic magnetoresistors are needed to sense the magnetic field. That is to say, the magnetic field sensing device of the prior art often requires a large layout area, resulting in an increase in production cost.

The invention provides a magnetic field sensing device and a detecting method thereof, which can effectively improve the accuracy of magnetic field sensing, reduce the volume of the magnetic field sensing device, and save cost.

The magnetic field sensing device of the present invention includes a first anisotropic magnetoresistance, a second anisotropic magnetoresistance, a current generator, and an arithmetic unit. The magnetization direction of the first anisotropic magnetoresistance is set to the first direction. The magnetization direction of the second anisotropic magnetoresistance is set to a second direction that is opposite or identical to the first direction. When the resistance value of the first anisotropic magnetoresistance increases according to the measured magnetic field, the resistance value of the second anisotropic magnetoresistance decreases correspondingly; in addition, when the resistance value of the first anisotropic magnetoresistance is based on the measured magnetic field When decreasing, the resistance value of the second anisotropic magnetoresistance increases correspondingly. The current generator is coupled to the first anisotropic magnetoresistance and the second anisotropic magnetoresistance. The current generator provides a current in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance. The operator is coupled to the first anisotropic magnetoresistance, the second anisotropic magnetoresistance, and the current generator. The operator obtains the first detection voltage according to the voltage difference between the two ends of the first anisotropic magnetoresistance, obtains the second detection voltage according to the voltage difference between the two ends of the second anisotropic magnetoresistance, and then detects the first detection voltage. The voltage and the second detected voltage are arithmetically operated to obtain a first magnetic field detection result.

In an embodiment of the invention, the operator includes a first operational amplifier, a second operational amplifier, and an arithmetic operator. The first input end of the first operational amplifier is coupled to the first end of the first anisotropic magnetoresistance, and the second end of the first operational amplifier is coupled to the second end of the first anisotropic magnetoresistance and coupled to Referring to the ground terminal, the output of the first operational amplifier generates a first detection voltage. The first input end of the second operational amplifier is coupled to the first end of the second anisotropic magnetoresistance, and the second end of the second operational amplifier is coupled to the second end of the second anisotropic magnetoresistance and coupled to Referring to the ground, the output of the second operational amplifier generates a second detection voltage. The arithmetic operator is coupled to the output end of the first operational amplifier and the output end of the second operational amplifier, and performs an arithmetic operation on the second detection voltage and the second detection voltage to obtain a first magnetic field detection result.

In an embodiment of the invention, the arithmetic operator is a subtractor, and the arithmetic operation is a subtraction operation.

In an embodiment of the invention, the current generator includes a first current source and a second current source. The first current source is coupled to the first end of the first anisotropic magnetoresistance to provide a first current flowing through the first anisotropic magnetoresistance in a direction parallel to the first direction. The second current source is coupled to the first end of the second anisotropic magnetoresistance to provide a second current flowing through the second anisotropic magnetoresistance in a direction parallel to the first direction.

In an embodiment of the invention, the operator includes a first operational amplifier, a second operational amplifier, and an arithmetic operator. The first input end of the first operational amplifier is coupled to the first end of the first anisotropic magnetoresistance, and the second end of the first operational amplifier is coupled to the second end of the first anisotropic magnetoresistance and the second At a first end of the directional magnetic resistance, a first detection voltage is generated at an output of the first operational amplifier. The first input end of the second operational amplifier is coupled to the first end of the second anisotropic magnetoresistance, and the second end of the second operational amplifier is coupled to the second end of the second anisotropic magnetoresistance and coupled to Referring to the ground, the output of the second operational amplifier generates a second detection voltage. The arithmetic operator is coupled to the output end of the first operational amplifier and the output end of the second operational amplifier, and performs an arithmetic operation on the second detection voltage and the second detection voltage to obtain a first magnetic field detection result.

In an embodiment of the invention, the current generator provides a first current to the first end of the first anisotropic magnetoresistance and causes the first current to flow through the first difference according to a direction parallel to the first direction. The directional magnetoresistance and the second anisotropic magnetoresistance.

In an embodiment of the invention, after the first magnetic field detection result is generated, the magnetization direction of the first anisotropic magnetoresistance is changed to the reverse direction of the first direction, and the magnetization of the second anisotropic magnetoresistance The direction is changed to the reverse direction of the second direction, and the operator obtains the third detection voltage according to the voltage difference between the two ends of the first anisotropic magnetoresistance, and obtains the voltage difference between the two ends of the second anisotropic magnetoresistance. The fourth detecting voltage performs an arithmetic operation on the third detecting voltage and the fourth detecting voltage to obtain a second magnetic field detecting result.

In an embodiment of the invention, the computing unit further includes performing an arithmetic operation on the first magnetic field detecting result and the second magnetic field detecting result to obtain a third magnetic field detecting result.

In an embodiment of the invention, the first anisotropic magnetoresistance and the second anisotropic magnetoresistance are disposed on the same substrate.

In an embodiment of the invention, each of the first anisotropic magnetoresistance and the second anisotropic magnetoresistance comprises a ferromagnetic strip. The ferromagnetic strip includes a plurality of shorting bars coupled in series, each shorting bar having a tapered end point.

In an embodiment of the invention, the magnetic field sensing device further includes a plurality of magnetization direction setting elements respectively disposed adjacent to the first anisotropic magnetoresistance and the first anisotropy magnetoresistance. The magnetization direction setting element is configured to respectively set a first anisotropy magnetoresistance and a magnetization direction of the first anisotropic magnetoresistance.

The magnetic field sensing method of the present invention comprises: providing a first anisotropic magnetoresistance and setting a magnetization direction thereof to a first direction; providing a second anisotropic magnetoresistance and setting a magnetization direction thereof to a second direction, wherein the second The direction is opposite or the same as the first direction, and when the resistance value of the first anisotropic magnetoresistance increases according to the measured magnetic field, the resistance value of the second anisotropic magnetoresistance decreases correspondingly; when the first anisotropic magnetic When the resistance value of the resistor decreases according to the measured magnetic field, the resistance value of the second anisotropic magnetoresistance increases correspondingly; the current is supplied in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance and the second difference a directional magnetic resistance; the first detection voltage and the second detection voltage are respectively obtained according to a voltage difference between the two ends of the first anisotropic magnetoresistive resistor and a voltage difference between the two ends of the second anisotropic magnetoresistance; Performing an arithmetic operation on the first detection voltage and the second detection voltage to obtain a first magnetic field detection result.

Based on the above, embodiments of the present invention provide a first anisotropic magnetoresistance having a reverse or the same magnetization setting direction and a second anisotropic magnetoresistance to perform a sensing action of a magnetic field, and when the first anisotropic magnetoresistance When the resistance value increases according to the measured magnetic field, the resistance value of the second anisotropic magnetoresistance decreases correspondingly; when the resistance value of the first anisotropic magnetoresistance decreases according to the measured magnetic field, the second anisotropic magnetic field The resistance value of the resistor is correspondingly increased. The embodiment of the present invention only needs to pass through two anisotropic magnetoresistors to complete the magnetic field sensing action, effectively reducing the circuit layout area of the magnetic field sensing device, and effectively reducing the production cost. In addition, the embodiment of the present invention can counteract the influence of the electrical offset generated by the system by performing an arithmetic operation on the detection voltage generated by the anisotropic magnetoresistance according to different resistance change trends. It can reduce the influence of environmental noise and electrical parameter drift caused by temperature changes, and effectively improve the accuracy of magnetic field sensing.

The above described features and advantages of the invention will be apparent from the following description.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of a magnetic field sensing device according to an embodiment of the present invention. The magnetic field sensing device 100 includes anisotropic magnetoresistances 110 and 120, a current generator 130, and an arithmetic unit 140. The anisotropic magnetoresistance 110 is connected in series between the current generator 130 and the arithmetic unit 140, and the magnetization direction of the anisotropic magnetoresistive resistor 110 during an initial period of time before the magnetic field sensing device 100 performs magnetic field sensing. It is set to direction D1. The anisotropic magnetoresistance 120 is connected in series between the current generator 130 and the arithmetic unit 140. The magnetization direction of the anisotropic magnetoresistive resistor 120 is enabled during the initial period of time before the magnetic field sensing device 100 performs magnetic field sensing. Set to direction D2, where direction D1 is opposite to direction D2.

The anisotropic magnetoresistances 110 and 120 provide resistance values R1 and R2, respectively. Under the influence of the anisotropic magnetoresistances 110 and 120, the resistance values R1 and R2 respectively provided by the anisotropic magnetoresistances 110 and 120 may be the same. The magnetization directions set by the anisotropy magnetoresistances 110 and 120 are opposite. When the anisotropic magnetoresistances 110 and 120 receive the influence of the external magnetic field, the resistance value R1 of the anisotropic magnetoresistor 110 is changed. The tendency of the trend and the resistance value R2 provided by the anisotropic magnetoresistive resistor 120 is reversed. Specifically, when the resistance value R1 provided by the anisotropic magnetoresistive resistor 110 is increased by the influence of the external magnetic field, the resistance value R2 provided by the anisotropic magnetoresistive resistor 120 is correspondingly reduced. In contrast, when the resistance value R1 provided by the anisotropic magnetoresistive resistor 110 is reduced by the influence of the external magnetic field, the resistance value R2 provided by the anisotropic magnetoresistive resistor 120 is correspondingly increased.

Current generator 130 provides current I1 in direction D1 to flow through anisotropic magnetoresistive resistor 110 and provides current I2 in a direction parallel to direction D1 to flow through anisotropic magnetoresistive resistor 120. In addition, the computing unit 140 is coupled to the two ends of the anisotropic magnetoresistive resistor 110 and coupled to the two ends of the anisotropic magnetoresistive resistor 120. The operator 140 generates a first detection voltage according to a voltage difference between two ends of the anisotropic magnetoresistive resistor 110, and generates a second detection voltage according to a voltage difference between two ends of the anisotropic magnetoresistive resistor 120. The magnetic field detection result V _O is generated by performing an arithmetic operation on the first detection voltage and the second detection voltage.

Regarding the details of the action of the magnetic field sensing, when the magnetic field sensing device 100 performs the magnetic field sensing action, the resistance values R1 and R2 provided by the anisotropic magnetoresistances 110, 120 will follow the measured magnetic field in the direction H (where the direction H is vertical) A change occurs in the component in the extending direction of the anisotropic magnetoresistances 110, 120. For example, when the component of the measured magnetic field in the direction H is not 0, the resistance value R1 provided by the anisotropic magnetoresistor 110 can be changed to be more R+DR, and the resistance value R1 provided by the anisotropic magnetoresistive resistor 120 is Change to R-DR. Through the currents I1 and I2 supplied from the current generator 130, the voltage difference between the two ends of the anisotropic magnetoresistor 110 can be increased as the strength of the measured magnetic field increases, and the voltage difference between the two ends of the anisotropic magnetoresistive resistor 120 can be It becomes smaller as the strength of the measured magnetic field increases. Based on the voltage difference between the two ends of the anisotropic magnetoresistances 110 and 120, the arithmetic unit 140 can obtain the first detection voltage and the second detection voltage, respectively. And performing an arithmetic operation (for example, subtraction) on the first detection voltage and the second detection voltage, and the operator 140 obtains the first magnetic field detection result V _O .

As can be seen from the above description, when the measured magnetic field H increases, the voltage difference between the two ends of the anisotropic magnetoresistor 110 gradually increases, and the voltage difference between the two ends of the anisotropic magnetoresistive resistor 120 gradually decreases. Comparing the voltage difference between the two ends of the anisotropic magnetoresistive resistor 110 and the voltage difference between the two ends of the anisotropic magnetoresistive resistor 120, the change trend of the measured magnetic field can be known and reflected in the first magnetic field detection result. _O.

In the present embodiment, the magnitudes of the current values of the currents I1 and I2 supplied by the current generator 130 may be the same. The current generator 130 is constructed in such a manner that a current mirror circuit is used to generate a current I1 and I2 according to a predetermined reference current. Of course, the construction of the current generator 130 described above is merely an example and is not intended to limit the scope of the present invention. Current generating circuits well known to those of ordinary skill in the art can be utilized to design the current generator 130 of the present invention.

In the present embodiment, the anisotropic magnetoresistances 110 and 120 may be disposed on the same substrate. The material of the substrate can be 矽, glass or any other material that can mechanically support the magnetic field sensing device 100. In an embodiment of the invention, the sensing device 100 can be disposed on a semiconductor wafer and formed through the design of the integrated circuit.

Please refer to FIG. 2, which is a schematic diagram of a magnetic field sensing device according to another embodiment of the present invention. The magnetic field sensing device 200 includes anisotropic magnetoresistors 210, 220, a current generator 230, and an operator 240. In the present embodiment, the current generator 230 includes current sources IS1 and IS2, and supplies currents I1, I2 to the anisotropic magnetoresistors 210 and 220, respectively, according to the direction D1. The operator 240 includes an operational amplifier OP1 and an OP2 and an arithmetic operator 241. The positive input terminal of the operational amplifier OP1 is coupled to the first end of the anisotropic magnetoresistive resistor 210, and the negative input terminal of the operational amplifier OP1 is coupled to the The second end of the anisotropic magnetoresistor 210 is used to detect a voltage difference between both ends of the anisotropic magnetoresistor 210. The positive input terminal of the operational amplifier OP2 is coupled to the first end of the anisotropic magnetoresistor 220, and the negative input terminal of the operational amplifier OP2 is coupled to the second end of the anisotropic magnetoresistor 220, thereby detecting the anisotropic magnetic The voltage difference between the two ends of the resistor 220. In addition, the negative input terminals of the operational amplifiers OP1 and OP2 are coupled to the reference ground GND.

The arithmetic operator 241 is coupled to the output terminals of the operational amplifiers OP1 and OP2, and receives the first detection voltage V1 and the second detection voltage V2 respectively generated by the operational amplifiers OP1 and OP2, and is configured for the first detection voltage V1 and The second detection voltage V2 is subtracted to generate a first magnetic field detection result V _O .

Regarding the details of the operation of the magnetic field sensing device 200, in the initial time before the sensing operation, the magnetization directions of the anisotropic magnetoresistors 210 and 220 can be set first, and the magnetization of the anisotropic magnetoresistors 210 and 220 can be made. The opposite direction. In the present embodiment, the magnetization direction of the anisotropic magnetoresistive resistor 210 is set to the direction D1, and the magnetization direction of the anisotropic magnetoresistive resistor 220 is set to the direction D2. After the setting operation of the magnetization direction is completed, the magnetization direction setting operation of the anisotropic magnetoresistances 210 and 220 can be stopped, and the sensing operation of the magnetic field is started.

According to the measured magnetic field H, the resistance values R1 and R2 respectively provided by the anisotropic magnetoresistors 210, 220 vary according to the opposite trend, for example, when the resistance value R1 provided by the anisotropic magnetoresistor 210 increases, the anisotropy When the resistance value R2 provided by the magnetic resistance 220 corresponds to decrease, or when the resistance value R1 provided by the anisotropic magnetoresistor 210 decreases, the resistance value R2 provided by the anisotropic magnetoresistor 220 increases correspondingly. Incidentally, when the measured magnetic field H is equal to 0, the resistance values R1 and R2 respectively provided by the anisotropic magnetoresistances 210, 220 are maintained equal to the initial state.

At the same time, currents IS1 and IS2 in current generator 230 provide currents I1 and I2, respectively, in accordance with direction D1 to flow through anisotropic magnetoresistors 210 and 220. The operational amplifiers OP1 and OP2 respectively extract the voltage difference between the two ends of the anisotropic magnetoresistances 210 and 220, and amplify the received voltage difference to respectively generate the first detection voltage V1 and the second detection voltage V2. . The operator 241 subtracts the second detection voltage V2 from the first detection voltage V1 to generate a first magnetic field detection result V _O .

Please refer to FIG. 2 and FIG. 3 simultaneously. FIG. 3 is a waveform diagram of magnetic field detection results according to an embodiment of the present invention. In FIG. 3, the vertical axis represents the voltage value of the first magnetic field detection result V _O , and the horizontal axis represents the magnitude of the magnetic field H to be measured. When the measured magnetic field H is in a fixed range, the resistance values R1 and R2 respectively provided by the anisotropic magnetoresistors 210 and 220 are linearly related to the measured magnetic field H, and the resistance value R1 is positively correlated with the measured magnetic field H. The resistance value R2 is negatively correlated with the measured magnetic field H.

In FIG 3, when the second detection voltage detected by the operational amplifier OP1 and the magnetic field H ₀ is equal to H, the first detection voltage V1 generated by the operational amplifier OP1 = V + DV generated V2 = V - DV, wherein V is the reference voltage (that is, the voltage generated by the operational amplifiers OP1, OP2 when the measured magnetic field H is equal to zero). By subtracting the first detection voltage V1 from the second detection voltage V2, the first magnetic field detection result V _O = V + DV - (V - DV) = 2 × DV can be obtained.

It can be seen from the above description that the embodiments of the present invention provide the anisotropic magnetoresistors 210 and 220 to obtain the first and second detection voltages V1 and V2, and transmit the first and second detection voltages V1 and V2. The subtraction action generates the first magnetic field detection result V _O , so that the influence of the environmental noise on the magnetic field sensing device 200 can be reduced, and the accuracy of the detection result can be improved.

Please refer to FIG. 4, which is a schematic diagram of another sensing stage of the magnetic field sensing device of the embodiment of FIG. 2 of the present invention. In order to improve the accuracy of the magnetic field sensing, in the embodiment of FIG. 4, a further phase of the sensing action is transmitted to generate a more accurate second magnetic field detecting result V _O ^' .

In FIG. 4, after the first magnetic field detection result V _{O is} generated, the next setting of the magnetization directions of the anisotropic magnetoresistors 210 and 220 can be performed, and the magnetization directions of the anisotropic magnetoresistors 210 and 220 are respectively Change to the opposite direction D2 and direction D1. After the adjustment of the magnetization directions of the anisotropic magnetoresistors 210 and 220 is completed, the current generator 230 again supplies the currents I1 and I2 in the direction D1 to flow through the anisotropic magnetoresistors 210 and 220, respectively. Then, the operational amplifiers OP1 and OP2 can generate the first detection voltage V1 ^′ and the second detection voltage V2 ^′ according to the voltage difference between the two ends of the anisotropic magnetoresistors 210 and 220, respectively, and the arithmetic operator 241 can The first detection voltage V1 ^′ and the second detection voltage V2 ^{′ are} subjected to subtraction to generate a second magnetic field detection result V _O ^′ .

Please refer to FIG. 4 and FIG. 5 simultaneously. FIG. 5 is a waveform diagram of the magnetic field detection result in the second stage of the embodiment of the present invention. In FIG. 5, the vertical axis represents the voltage value of the first magnetic field detection result V _O , and the horizontal axis represents the magnitude of the measured magnetic field H. When the measured magnetic field H is in a fixed range, the resistance values R1 and R2 respectively provided by the anisotropic magnetoresistors 210 and 220 are linearly related to the measured magnetic field H. Unlike FIG. 3, in FIG. 5, the resistance value R1 is negatively correlated with the measured magnetic field H, and the resistance value R2 is positively correlated with the measured magnetic field H.

In FIG. 5, when the ^'second detection voltage V2 and the operational amplifier OP1 = V + DV ^produced' by measuring the magnetic field H ₀ is equal to H, the operational amplifier OP1 generated by the first detection voltage V1 = V - DV Where V is the reference voltage. By subtracting the first detection voltage V1 ^' from the second detection voltage V2 ^' , the second magnetic field detection result V _O ^' = V - DV - (V + DV) = -2 × DV can be obtained. Next, the arithmetic circuit 240 performs a further subtraction of the first magnetic field detection result V _O and the second magnetic field detection result V _O ^' , and obtains a third magnetic field detection result equal to 4×DV.

Please note that the influence of the DC offset of the operational amplifiers OP1 and OP2 is further reduced by the first magnetic field detection result V _O and the second magnetic field detection result V _O ^' . The compensation can be effectively obtained and the accuracy of the magnetic field detection result can be improved.

Incidentally, the terminal connection relationship between the positive and negative input terminals of the operational amplifiers OP1 and OP2 and the anisotropy magnetoresistors 210 and 220 can be changed. For example, the positive and negative inputs of the operational amplifier OP2 in FIGS. 2 and 4 can be exchanged, and the arithmetic operator 241 can be correspondingly changed to an adder, so that the magnetic field sensing device 200 can still generate the same. Magnetic field detection results. That is to say, those skilled in the art can adjust the end point connection relationship between the operational amplifiers OP1 and OP2 and the anisotropic magnetoresistors 210 and 220 and the arithmetic operation operated by the arithmetic operator 241 according to the above principle, and This implementation can be implemented.

Please refer to FIG. 6. FIG. 6 is a schematic diagram of a magnetic field sensing device according to still another embodiment of the present invention. The magnetic field sensing device 600 includes anisotropic magnetoresistances 610, 620, a current generator 630, and an operator 640. The arithmetic unit 640 includes an operational amplifiers OP1 and OP2 and an arithmetic operation unit 641. Different from the foregoing embodiments, the anisotropic magnetoresistors 610 and 620 are coupled in series with each other, wherein the first end of the anisotropic magnetoresistance 610 is coupled to the current generator 630 and the operational amplifier OP1. The second input of the anisotropic magnetoresistance 610 is coupled to the negative input terminal of the operational amplifier OP1 and coupled to the first end of the anisotropic magnetoresistor 620. In addition, the first end of the anisotropic magnetoresistance 620 is coupled to the positive input terminal of the operational amplifier OP2, and the second end of the anisotropic magnetoresistance 620 is coupled to the negative input terminal of the operational amplifier OP2 and the reference ground terminal. GND.

Based on the fact that the anisotropic magnetoresistors 610, 620 are coupled in series with each other, the current generator 630 requires only a single current source IS3 to generate the current I1. The current generator 630 sequentially transmits the current I1 according to the direction D1 through the anisotropic magnetoresistances 610 and 620. Based on the architecture of the present embodiment, the magnetic field sensing device 600 of the embodiment of the present invention can be permeable to the magnetic field sensing device 600 of the embodiment of the present invention by setting the anisotropic magnetoresistance 610, 620 having the opposite magnetization direction and transmitting the magnetic field sensing method of the first or second stage. The arithmetic operation of the arithmetic operator 641 obtains the magnetic field detection result V _O .

7A and 7B, FIGS. 7A and 7B illustrate a method of laying out an anisotropic magnetoresistance according to various embodiments of the present invention. Wherein, the anisotropic magnetoresistances 710 and 720 may have a barber pole-like structure, that is, a plurality of short circuits whose surfaces are inclined by 45 degrees with respect to the extending direction of the anisotropic magnetoresistances 710 and 720. SB (electrical shorting bar), these shorting bars are disposed on the ferromagnetic film FF (spacer film) spaced apart from each other, and the ferromagnetic film FF is the main body of the anisotropic magnetoresistance 710, 720, and the extending direction thereof is It is the extending direction of the anisotropic magnetoresistance FF. Further, the opposite ends of the ferromagnetic film FF can be formed in a tip shape.

In FIG. 7A, the anisotropic magnetoresistor 710 and the anisotropic magnetoresistor 720 can be arranged separately. Wherein, the anisotropic magnetoresistive resistor 710 is disposed on the magnetization direction setting component C1, the anisotropic magnetoresistive resistor 720 is disposed on the magnetization direction setting component C2, and the anisotropic magnetoresistive resistor 710 is coupled to the end point P2 and the end point. Between P2, the anisotropic magnetoresistance 720 is coupled between the end point P2 and the end point P1. The anisotropic magnetoresistances 710, 720 of FIG. 7A can be respectively applied to the anisotropic magnetoresistors 210, 220 of the embodiment of FIG. 2 of the present invention, wherein the terminal P1 can be coupled to the positive input terminal of the operational amplifier OP2 and receive current. I2, the terminal P3 can be coupled to the positive input terminal of the operational amplifier OP1 and receive the current I1, and the terminal P2 can be coupled to the reference ground GND and the negative input terminals of the operational amplifiers OP1, OP2. In addition, the anisotropic magnetoresistors 710 and 720 of FIG. 7A can also be respectively applied to the anisotropic magnetoresistors 610 and 620 of the embodiment of FIG. 6 of the present invention, wherein the terminal P2 can be coupled to the negative input terminal of the operational amplifier OP1. And the positive input terminal of the operational amplifier OP2, the terminal P3 can be coupled to the positive input terminal of the operational amplifier OP1 and receive the current I1, and the terminal P1 can be coupled to the reference ground GND and the negative input terminal of the operational amplifier OP2. The magnetization direction setting elements C1, C2 are, for example, coils, wires or conductors which can respectively generate two magnetic fields which are parallel to the direction in which the ferromagnetic film FF extends, and which pass through the ferromagnetic film FF and are opposite in direction, by means of a current. The magnetization directions of the directional magnetoresistances 710 and 720 are set to the direction D1 and the direction D2, respectively.

In FIG. 7B, the anisotropic magnetoresistance 730 and the anisotropic magnetoresistance 740 are alternately arranged. Among them, a part of the anisotropic magnetoresistance 730 and a part of the anisotropic magnetoresistance 740 are alternately arranged in the magnetization direction setting element C1, and another part of the anisotropic magnetoresistance 730 and another part of the anisotropic magnetoresistance 740 are alternately arranged in The magnetization direction setting element C2. The anisotropic magnetoresistance 730 is coupled between the terminal P5 and the terminal P6, and the anisotropic magnetoresistance 720 is coupled between the terminal P5 and the end point P4. It is to be noted that the partial anisotropic magnetoresistance 730 and the partial anisotropic magnetoresistance 740 disposed in the same magnetization direction setting element are complementary in the direction of the shorting bars, and are partially in the opposite direction of the dissimilar magnetization direction setting elements. The magnetic resistance 730 (or the anisotropic magnetoresistance 740) has complementary directions of the shorting bars.

The anisotropic magnetoresistance 730 and the anisotropic magnetoresistor 740 of FIG. 7B are equally applicable to the magnetic field sensing devices 200, 600 of the present embodiment of FIGS. When applied to the magnetic field sensing device 200, the terminal P4 can be coupled to the positive input terminal of the operational amplifier OP2 and receive the current I2. The terminal P6 can be coupled to the positive input terminal of the operational amplifier OP1 and receive the current I1. P5 can be coupled to the reference ground GND and the negative inputs of the operational amplifiers OP1, OP2. When applied to the magnetic field sensing device 600, the terminal P5 can be coupled to the negative input terminal of the operational amplifier OP1 and the positive input terminal of the operational amplifier OP2, and the terminal P6 can be coupled to the positive input terminal of the operational amplifier OP1 and receive the current I1. The terminal P4 can be coupled to the reference ground GND and the negative input of the operational amplifier OP2.

Please refer to FIG. 8 . FIG. 8 is a flowchart of a magnetic field sensing method according to an embodiment of the present invention. Step S810 provides a first anisotropic magnetoresistance and sets its magnetization direction to a first direction, and step S820 provides a second anisotropic magnetoresistance and sets its magnetization direction to a second direction, wherein the second direction is first The opposite direction. Next, in step S830, a current is supplied in the first direction to flow through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance. Step S840, respectively, obtaining the first detection voltage and the second detection voltage according to the voltage difference between the two ends of the first anisotropic magnetoresistive resistor and the voltage difference between the two ends of the second anisotropic magnetoresistance, and in step S850. Performing an arithmetic operation on the first detection voltage and the second detection voltage to obtain a first magnetic field detection result.

The implementation details of the above steps have been described in detail in the foregoing various embodiments, and will not be further described below.

Referring to FIG. 7A and FIG. 7B again, in the above embodiment, the magnetic field setting directions of the anisotropic magnetoresistors 710 and 720 are exemplified by two opposite directions D1 and D2, but in another embodiment, the figure may be The short-circuit bar SB direction of the anisotropic magnetoresistance 720 of 7A is changed to the short-circuit bar SB direction of the anisotropic magnetoresistance 740 on the right side of the reference numeral 740 of FIG. 7B (that is, 90 degrees difference from the original, but the extension direction of the short-circuit bar SB is It is 45 degrees with the extending direction of the ferromagnetic film FF). Regarding the characteristics of the anisotropic magnetoresistance, when the external magnetic field is fixed and the shorting bar is rotated by 90 degrees, the resistance value of the anisotropic magnetoresistance is changed from a ΔR value to a ΔR value, or from the original value. A ΔR value becomes an increase ΔR value, and a ΔR value corresponds to a magnitude of a component of an external magnetic field perpendicular to the ferromagnetic film FF; this is also the case when the magnetic field setting direction becomes reversed; however, when the ferromagnetic film FF When the direction of the current is reversed, this is not the case, but the direction of change of the resistance value of the anisotropic magnetoresistance remains unchanged. Therefore, in this other embodiment, since the shorting bar SB direction of the anisotropic magnetoresistance 720 of FIG. 7A is changed to the shorting bar SB direction of the anisotropic magnetoresistance 740 of the right side of the reference numeral 740 of FIG. 7B, it is different. The extending direction of the shorting bar SB of the directional magnetoresistive resistor 210 is perpendicular to the extending direction of the shorting bar SB of the anisotropic magnetoresistive SB. At this time, the direction (direction D1) and the anisotropy of the magnetic field of the anisotropic magnetoresistor 710 are set. The magnetic field setting direction (direction D2) of the magnetoresistive 720 can be changed to be in the same direction, that is, both the direction D1 and the direction D2 are toward the left side of FIG. 7A, or both the direction D1 and the direction D2 are toward the right of FIG. 7A, so that The anisotropy magnetoresistances 710 and 720 have substantially the same magnitude of change in the resistance value of the measured magnetic field H, and for example, the resistance values of the two are ΔR and -ΔR, respectively. In still another embodiment, at the next moment, the magnetic field setting direction of the anisotropic magnetoresistance 710, 720 can be reversed. For example, the directions D1 and D2 are both changed to the left, or the direction D1. Both D2 and D2 were originally turned to the left and turned to the left.

In summary, embodiments of the present invention provide a pair of first anisotropic magnetoresistance and a second anisotropic magnetoresistance, and have opposites by setting a first anisotropic magnetoresistance and a second anisotropic magnetoresistance Or the same magnetization direction, and when the resistance value of the first anisotropic magnetoresistance increases according to the measured magnetic field, the resistance value of the second anisotropic magnetoresistance decreases correspondingly; when the resistance of the first anisotropic magnetoresistance When the value decreases according to the measured magnetic field, the resistance value of the second anisotropic magnetoresistance increases correspondingly. In addition, the magnetic field detection result is calculated by detecting the voltage difference generated by the first anisotropy magnetoresistance and the second anisotropy magnetoresistance receiving the same current. In this way, the present invention only needs the paired first anisotropic magnetoresistance and the second anisotropic magnetoresistance to complete the magnetic field sensing action, effectively reducing the component layout area required for the magnetic field sensing device, and effectively reducing the cost. . In addition, the arithmetic operation of the voltage difference of the paired anisotropic magnetoresistance can effectively reduce the influence of environmental noise on the sensing result, and the DC offset of the circuit component and the electrical drift caused by the temperature can also be combined. Get compensation to improve the accuracy of the sensing results.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100, 200, 600‧‧‧ magnetic field sensing device
110, 120, 210, 220, 610, 620, 710, 720, 730, 740‧‧‧ anisotropic magnetoresistance
130, 230, 630‧‧‧ current generator
140, 240, 640‧‧‧ arithmetic
R1, R2‧‧‧ resistance value
D1, D2‧‧‧ direction
I1, I2‧‧‧ current
V _O , V _O ^' ‧ ‧ first magnetic field detection results
V1, V2, V1 ^' , V2 ^' ‧ ‧ detection voltage
OP1, OP2‧‧‧Operational Amplifier
241, 641‧‧ ‧ Arithmetic Operator
IS1~IS3‧‧‧current source
GND‧‧‧reference ground voltage
H‧‧‧Measured magnetic field
H ₀ ‧‧‧Magnetic field
P1~P6‧‧‧ endpoint
C1, C2‧‧‧ Magnetization direction setting component
S810~S850‧‧‧Steps for magnetic field sensing method

FIG. 1 is a schematic diagram of a magnetic field sensing device according to an embodiment of the invention. 2 is a schematic diagram of a magnetic field sensing device according to another embodiment of the present invention. FIG. 3 is a waveform diagram showing magnetic field detection results according to an embodiment of the present invention. 4 is a schematic view showing the operation of another sensing stage of the magnetic field sensing device of the embodiment of FIG. 2 of the present invention. FIG. 5 is a waveform diagram showing magnetic field detection results in the second stage of the embodiment of the present invention. 6 is a schematic diagram of a magnetic field sensing device according to still another embodiment of the present invention. 7A and 7B illustrate a method of laying out an anisotropic magnetoresistance of different embodiments of the present invention. FIG. 8 is a flow chart of a magnetic field sensing method according to an embodiment of the present invention.

100‧‧‧ Magnetic field sensing device

110, 120‧‧‧ anisotropic magnetoresistance

130‧‧‧current generator

140‧‧‧Operator

R1, R2‧‧‧ resistance value

D1, D2‧‧‧ direction

I1, I2‧‧‧ current

H‧‧‧Measured magnetic field

V _O ‧‧‧First magnetic field detection result

Claims (17)

A magnetic field sensing device comprising: a first anisotropic magnetoresistance whose magnetization direction is set to a first direction; and a second anisotropic magnetoresistance whose magnetization direction is set to a second direction, wherein The second direction is opposite or the same as the first direction, and when the resistance value of the first anisotropic magnetoresistance increases according to a measured magnetic field, the resistance value of the second anisotropic magnetoresistance decreases correspondingly. When the resistance value of the first anisotropic magnetoresistance decreases according to a measured magnetic field, the resistance value of the second anisotropic magnetoresistance increases correspondingly; a current generator coupled to the first anisotropic magnetoresistance And the second anisotropic magnetoresistance, providing a current in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance; and an operator coupled to the current The first anisotropy magnetoresistance, the second anisotropic magnetoresistance, and the current generator obtain a first detection voltage according to a voltage difference between the two ends of the first anisotropic magnetoresistance, according to the second difference Obtaining a second detection voltage between the voltage difference between the two ends of the directional magnetoresistance, and then Performing an arithmetic operation on the first detection voltage and the second detection voltage to obtain a first magnetic field detection result. The magnetic field sensing device of claim 1, wherein the computing device comprises: a first operational amplifier, the first input end of which is coupled to the first end of the first anisotropic magnetoresistance, the first The second end of the operational amplifier is coupled to the second end of the first anisotropic magnetoresistor and coupled to a reference ground, the output of the first operational amplifier generates the first detection voltage; An operational amplifier, the first input end of which is coupled to the first end of the second anisotropic magnetoresistance, and the second end of the second operational amplifier is coupled to the second end of the second anisotropic magnetoresistor and coupled Connected to the reference ground, the output of the second operational amplifier generates the second detection voltage; and an arithmetic operator coupled to the output of the first operational amplifier and the output of the second operational amplifier The second detection voltage and the second detection voltage perform the arithmetic operation to obtain a first magnetic field detection result. The magnetic field sensing device of claim 2, wherein the arithmetic operator is a subtractor, and the arithmetic operation is a subtraction operation. The magnetic field sensing device of claim 2, wherein the current generator comprises: a first current source coupled to the first end of the first anisotropic magnetoresistor to provide a first current edge And flowing through the first anisotropic magnetoresistance in a direction parallel to the first direction; and a second current source coupled to the first end of the second anisotropic magnetoresistor to provide a second current along the parallel The direction of the first direction flows through the second anisotropic magnetoresistance. The magnetic field sensing device of claim 1, wherein the computing device comprises: a first operational amplifier, the first input end of which is coupled to the first end of the first anisotropic magnetoresistance, the first The second end of the operational amplifier is coupled to the second end of the first anisotropic magnetoresistance and the first end of the second anisotropic magnetoresistance, and the first end of the first operational amplifier generates the first detection a second operational amplifier, the first input end of which is coupled to the first end of the second anisotropic magnetoresistance, and the second end of the second operational amplifier is coupled to the second anisotropic magnetoresistance The second end is coupled to a reference ground, the output of the second operational amplifier generates the second detection voltage, and an arithmetic operator coupled to the output of the first operational amplifier and the second operational amplifier The output terminal performs the arithmetic operation on the second detection voltage and the second detection voltage to obtain a first magnetic field detection result. The magnetic field sensing device of claim 5, wherein the current generator provides a first current to the first end of the first anisotropic magnetoresistance and the first current is parallel to the first The direction of the direction sequentially flows through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance. The magnetic field sensing device of claim 1, wherein a magnetization direction of the first anisotropic magnetoresistor is changed to a reverse direction of the first direction after the first magnetic field detection result is generated, The magnetization direction of the second anisotropic magnetoresistance is changed to the reverse direction of the second direction, and the operator obtains a third detection voltage according to the voltage difference between the two ends of the first anisotropic magnetoresistance, according to the A voltage difference between the two ends of the second anisotropy magnetoresistor obtains a fourth detection voltage, and performs the arithmetic operation on the third detection voltage and the fourth detection voltage to obtain a second magnetic field detection result. The magnetic field sensing device of claim 7, wherein the computing device further comprises: performing the arithmetic operation on the first magnetic field detecting result and the second magnetic field detecting result to obtain a third magnetic field detecting result. . The magnetic field sensing device of claim 1, wherein the first anisotropic magnetoresistance and the second anisotropic magnetoresistance are disposed on the same substrate. The magnetic field sensing device of claim 1, further comprising: a plurality of magnetization direction setting elements respectively disposed adjacent to the first anisotropic magnetoresistance and the first anisotropic magnetoresistance The first anisotropic magnetoresistance and the magnetization direction of the first anisotropic magnetoresistance are set. A magnetic field sensing method includes: providing a first anisotropic magnetoresistance and setting a magnetization direction thereof to a first direction; providing a second anisotropic magnetoresistance and setting a magnetization direction to a second direction, Wherein the second direction is opposite or the same as the first direction, and when the resistance value of the first anisotropic magnetoresistance is increased according to a measured magnetic field, the resistance value of the second anisotropic magnetoresistance is correspondingly decreased. When the resistance value of the first anisotropic magnetoresistance decreases according to a measured magnetic field, the resistance value of the second anisotropic magnetoresistance correspondingly increases; providing current in a direction parallel to the first direction to flow Passing the first anisotropic magnetoresistance and the second anisotropic magnetoresistance; according to a voltage difference between the two ends of the first anisotropic magnetoresistive resistor and a voltage difference between the two ends of the second anisotropic magnetoresistive resistor Obtaining a first detection voltage and a second detection voltage respectively; and performing an arithmetic operation on the first detection voltage and the second detection voltage to obtain a first magnetic field detection result. The magnetic field sensing method according to claim 11, wherein the voltage difference between the two ends of the first anisotropic magnetoresistance and the voltage difference between the two ends of the second anisotropic magnetoresistance are respectively obtained. The step of detecting the first detection voltage and the second detecting voltage includes: providing a first operational amplifier to receive a voltage across the first anisotropic magnetoresistance, and according to a voltage difference across the first anisotropic magnetoresistance Generating the first detection voltage; and providing a second operational amplifier to receive the voltage across the second anisotropic magnetoresistor, and generating a second detection according to a voltage difference across the second anisotropic magnetoresistance Measure the voltage. The magnetic field sensing method of claim 11, wherein the method of providing a current in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance comprises Providing a first current in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance; and providing a second current in a direction parallel to the first direction to flow through the second anisotropy Magnetic resistance. The magnetic field sensing method of claim 11, wherein the method of providing a current in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance comprises Providing a first current sequentially flowing through the first anisotropic magnetoresistance and the second anisotropic magnetoresistance in a direction parallel to the first direction. The magnetic field sensing method of claim 11, after the first magnetic field detection result is generated, further comprising: changing a magnetization direction of the first anisotropic magnetoresistance to be a reverse direction of the first direction; Changing a magnetization direction of the second anisotropic magnetoresistance to a reverse direction of the second direction; providing a current in a direction parallel to the first direction to flow through the first anisotropic magnetoresistance and the second anisotropy a magnetic resistance; a voltage difference between the two ends of the first anisotropic magnetoresistance and a voltage difference between the two ends of the second anisotropic magnetoresistance to obtain a third detection voltage and a fourth detection voltage; And performing the arithmetic operation on the third detection voltage and the fourth detection voltage to obtain a second magnetic field detection result. The magnetic field sensing method of claim 15, further comprising: performing the arithmetic operation on the first magnetic field detecting result and the second magnetic field detecting result to obtain a third magnetic field detecting result. The magnetic field sensing method of claim 11, wherein the first anisotropic magnetoresistance and the second anisotropic magnetoresistance are disposed on the same substrate.