TWI703338B - Electric current sensor - Google Patents

Abstract

An electric current sensor including a substrate, a conductive wire, a first anisotropic magnetoresistor (AMR) unit, a second AMR unit, a third AMR unit, a fourth AMR unit, a first magnetization direction setting device, and a second magnetization direction setting device is provided. The conductive wire has a first conductive segment and a second conductive segment respectively disposed below a first end and a second end opposite thereto of the substrate. The first AMR unit and the second AMR unit are disposed above the first end of the substrate. The third AMR unit and the fourth AMR unit are disposed above the second end of the substrate. The first magnetization direction setting device and the second magnetization direction setting device are configured to set magnetization directions of the AMR units.

Description

Current sensor

The present invention relates to a sensor, and particularly relates to a current sensor.

Current sensing is one of the indispensable elements in industrial automation. In recent years, the demand for current sensing has expanded from industrial use to consumer products and applications in the field of smart homes and smart cities. High accuracy, fast response, small size, low power consumption and reliable quality have become the goals pursued by the new generation of current sensors.

There are many ways to measure the current in a conductor. For example, a shunt resistor can be used to calculate the current by measuring the voltage difference across it. However, this resistance has a small phasor and therefore high current consumption, which is not suitable for small or portable devices. In addition, high currents can generate heat and cause other problems.

The invention provides a current sensor with high sensitivity, high accuracy and low power consumption.

An embodiment of the present invention provides a current sensor that includes a substrate, a wire, a first anisotropic magnetoresistor (AMR) unit, a second anisotropic magnetoresistor, and a third anisotropic magnetoresistor. The directional magnetic resistance unit, a fourth anisotropic magnetic resistance unit, a first magnetization direction setting element, and a second magnetization direction setting element. The wire has a first conductive segment and a second conductive segment, wherein the first conductive segment and the second conductive segment are arranged in a first direction, each extend along a second direction, and are respectively disposed on an opposite side of the substrate Below the first end and a second end. The first anisotropic magnetic resistance unit and the second anisotropic magnetic resistance unit are disposed above the first end of the substrate and arranged along the first direction. The third anisotropic magnetoresistive unit and the fourth anisotropic magnetoresistive unit are disposed above the second end of the substrate and are arranged along the opposite direction of the first direction. The first magnetization direction setting element is used for setting the magnetization directions of the first anisotropic magnetoresistive unit and the second anisotropic magnetoresistive unit. The second magnetization direction setting element is used for setting the magnetization directions of the third anisotropic magnetic resistance unit and the fourth anisotropic magnetic resistance unit. When a current flows through the wire, due to the magnetic field generated by the current, the resistance change generated by the first anisotropic magnetoresistive unit is opposite to the resistance change generated by the second anisotropic magnetoresistive unit, and the first The resistance change produced by the three anisotropic magnetoresistive unit is opposite to the resistance change produced by the fourth anisotropic magnetoresistive unit, and the first, second, third and fourth anisotropic magnetoresistive units are electrically It is connected as a Wheatstone bridge to output a voltage signal corresponding to the resistance change generated by the first, second, third and fourth anisotropic magnetoresistive units.

In an embodiment of the present invention, the current sensor further includes an arithmetic unit electrically connected to an output terminal of the Wheatstone bridge, wherein the first magnetization direction setting element and the second magnetization direction setting element connect the first The magnetization direction combination of the second, third, and fourth anisotropic magnetoresistive units is set to a first combination, so that the Wheatstone bridge outputs a first voltage signal, and the first magnetization direction setting element and the first combination The second magnetization direction setting element then sets the magnetization direction combination of the first, second, third and fourth anisotropic magnetoresistive units to a second combination opposite to the first combination, so that the Wheatstone bridge outputs A second voltage signal. The arithmetic unit is used for subtracting the first voltage signal and the second voltage signal to output an output voltage signal corresponding to the magnitude of the magnetic field generated by the current.

In an embodiment of the present invention, the arithmetic unit is used to add the first voltage signal and the second voltage signal to output an offset voltage signal.

In an embodiment of the present invention, when current flows through the wire, the direction of current flow in the first conductive section is opposite to the direction of current flow in the second conductive section.

In an embodiment of the present invention, the first direction is perpendicular to the second direction.

In an embodiment of the present invention, when the current flows through the first conductive section, the direction of the component of the magnetic field generated at the first anisotropic magnetoresistance unit and the second anisotropic magnetoresistance unit in the first direction is opposite to The direction of the component in the first direction of the magnetic field generated at the third anisotropic magnetoresistance unit and the fourth anisotropic magnetoresistance unit when current flows through the second conductive section.

In an embodiment of the present invention, the Wheatstone bridge corresponding to the output voltage signal of the external magnetic field component in the first direction is zero, which corresponds to the voltage output of the external magnetic field component in the second direction The signal is zero, and the output voltage signal corresponding to the external magnetic field component in a third direction is zero, wherein the third direction is perpendicular to the first direction and the second direction.

In an embodiment of the present invention, the first anisotropic magnetoresistive unit includes a first anisotropic magnetoresistance and a second anisotropic magnetoresistance arranged in sequence along the opposite direction of the second direction, and the second The anisotropic magnetoresistive unit includes a third anisotropic magnetoresistance and a fourth anisotropic magnetoresistance that are arranged in sequence along the direction opposite to the second direction. The third anisotropic magnetoresistance unit includes A fifth anisotropic magnetoresistance and a sixth anisotropic magnetoresistance are arranged in sequence in a direction opposite to the direction, and the fourth anisotropic magnetoresistance unit includes a first Seven anisotropic magnetoresistance and an eighth anisotropic magnetoresistance.

In an embodiment of the present invention, at a first time, the first magnetization direction setting element sets the magnetization directions of the first anisotropic magnetic resistance and the third anisotropic magnetic resistance to the opposite direction of the second direction, and The magnetization directions of the second anisotropic magnetic resistance and the fourth anisotropic magnetic resistance are set to the second direction. At the first time, the second magnetization direction setting element sets the magnetization directions of the fifth anisotropic magnetic resistance and the seventh anisotropic magnetic resistance to the opposite direction of the second direction, and sets the sixth anisotropic magnetic resistance and the first The magnetization direction of the eight-anisotropic magnetoresistance is set to the second direction. At a second time, the first magnetization direction setting element sets the magnetization directions of the first anisotropic magnetoresistance and the third anisotropic magnetoresistance to the second direction, and sets the second anisotropic magnetoresistance to the fourth anisotropy The magnetization direction of the directional magnetoresistance is set to the opposite direction of the second direction. At the second time, the second magnetization direction setting element sets the magnetization directions of the fifth anisotropic magnetoresistance and the seventh anisotropic magnetoresistor to the second direction, and sets the sixth anisotropic magnetoresistance to the eighth anisotropy The magnetization direction of the magnetic resistance is set to the opposite direction of the second direction.

In an embodiment of the present invention, the first magnetization direction setting element and the second magnetization direction setting element are conductive sheets, conductive coils, wires or conductors.

In the current sensor of the embodiment of the present invention, since the anisotropic magnetoresistance unit is connected to form a Wheatstone bridge to sense the magnetic field generated by the current in the wire, it is highly sensitive to current sensing Degree and high accuracy. In addition, because the current sensor of the embodiment of the present invention uses the magnetic field generated by the sensing current to reverse the magnitude of the current, the anisotropic magnetoresistive unit does not directly contact the current, so it can have a lower Power consumption.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

1 is a schematic top view of a current sensor according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the current sensor of FIG. 1 along the line A-A. 1 and 2, the current sensor 100 of this embodiment includes a substrate 210, a wire 110, a first anisotropic magnetic resistance unit 222, a second anisotropic magnetic resistance unit 224, and a first Three anisotropic magnetic resistance unit 226, a fourth anisotropic magnetic resistance unit 228, a first magnetization direction setting element M1, and a second magnetization direction setting element M2. The wire 110 has a first conductive segment C1 and a second conductive segment C2, wherein the first conductive segment C1 and the second conductive segment C2 are arranged in a first direction D1, each extend along a second direction D2, and respectively It is disposed under a first end 212 and a second end 214 opposite to the substrate 210. The space in which the current sensor 100 exists can be constructed by a first direction D1, a second direction D2, and a third direction D3 that are different from each other. In this embodiment, the first direction D1, the second direction D2, and the third direction D3 can be perpendicular to each other. However, in other embodiments, the first direction D1, the second direction D2, and the third direction D3 may also be non-perpendicular and different from each other.

The first anisotropic magnetic resistance unit 222 and the second anisotropic magnetic resistance unit 224 are disposed above the first end 212 of the substrate 210 and are arranged along the first direction D1. The third anisotropic magnetoresistive unit 226 and the fourth anisotropic magnetoresistance unit 228 are disposed above the second end 214 of the substrate 210 and are arranged along the opposite direction of the first direction D1. The direction from below the first end 212 of the substrate 210 to above the first end 212 of the substrate 210 is the third direction D3.

The first magnetization direction setting element M1 is used to set the magnetization directions of the first anisotropic magnetoresistive unit 222 and the second anisotropic magnetoresistive unit 224. The second magnetization direction setting element M2 is used to set the magnetization directions of the third anisotropic magnetic resistance unit 226 and the fourth anisotropic magnetic resistance unit 228.

When a current I flows through the wire 110, due to the magnetic field generated by the current I, the resistance change generated by the first anisotropic magnetoresistive unit 222 is opposite to the resistance generated by the second anisotropic magnetoresistive unit 224 Value changes, and the resistance value change generated by the third anisotropic magnetoresistive unit 226 is opposite to the resistance value change generated by the fourth anisotropic magnetoresistive unit 228, and the first, second, third, and fourth different The directional magnetoresistance units 222, 224, 226 and 228 are electrically connected to form a Wheatstone bridge to output corresponding to the first, second, third and fourth anisotropic magnetoresistance units 222, 224, 226 and 228 The resulting voltage signal of the change in resistance value.

In this embodiment, the first anisotropic magnetoresistive unit 222 includes a first anisotropic magnetoresistor (AMR) R1 and a second anisotropic magnetoresistor (AMR) R1 and a second anisotropic magnetoresistor (AMR) arranged in sequence along the direction opposite to the second direction D2. The second anisotropic magnetoresistance unit 224 includes a third anisotropic magnetoresistance R3 and a fourth anisotropic magnetoresistance R4 arranged in sequence along the direction opposite to the second direction D2. The anisotropic magnetoresistive unit 226 includes a fifth anisotropic magnetoresistance R5 and a sixth anisotropic magnetoresistance R6 arranged in sequence along the direction opposite to the second direction D2, and a fourth anisotropic magnetoresistance unit 228 includes a seventh anisotropic magnetoresistance R7 and an eighth anisotropic magnetoresistance R8 arranged in sequence along the opposite direction of the second direction D2. The numbers of the first to eighth anisotropic magnetoresistor R1 to R8 mentioned above are each taken as an example. However, in other embodiments, each anisotropic magnetoresistance can also be connected in series with multiple anisotropic magnetoresistor Magnetoresistance to replace. For example, the first anisotropic magnetic resistance R1 can be replaced by a plurality of first anisotropic magnetic resistances R1 connected in series.

In this embodiment, the first magnetization direction setting element M1 and the second magnetization direction setting element M2, and the first to fourth anisotropic magnetoresistance units 222, 224, 226, and 228 may be disposed on the substrate 210, and the magnetization direction The setting element and the anisotropic magnetic resistance unit can be separated by an insulating layer. In this embodiment, the first magnetization direction setting element M1 is disposed between the first and second anisotropic magnetoresistance units 222, 224 and the first conductive segment C1, and the second magnetization direction setting element M2 is disposed on the third And between the fourth anisotropic magnetoresistive unit 226, 228 and the second conductive segment C2. However, in other embodiments, the first and second anisotropic magnetoresistive units 222, 224 may also be disposed between the first magnetization direction setting element M1 and the first conductive segment C1, and the third and fourth different The directional magnetoresistance units 226 and 228 are arranged between the second magnetization direction setting element M2 and the second conductive segment C2. Alternatively, in other embodiments, the first magnetization direction setting element M1 may also be distributed on the upper and lower sides of the first and second anisotropic magnetoresistive units 222, 224, and the second magnetization direction setting element M2 may also It may be distributed on the upper and lower sides of the third and fourth anisotropic magnetoresistive units 226 and 228.

In addition, the wire 110 may be covered by a package body 120, and both ends of the wire 110 are exposed outside the package body 120, where the package body 120 is, for example, an insulating material. The substrate 210 may be disposed on the package body 120.

3A and 3B are used to illustrate the operation principle of the anisotropic magnetoresistance in FIG. 1. Please refer to FIG. 3A first, the anisotropic magnetoresistor 300 has a barber pole-like structure, that is, its surface is provided with a plurality of shorting bars extending at an angle of 45 degrees with respect to the extending direction D of the anisotropic magnetoresistor 300 (Electrical shorting bar) 310, these shorting bars 310 are spaced apart from each other and arranged in parallel on the ferromagnetic film (ferromagnetic film) 320, and the ferromagnetic film 320 is the main body of the anisotropic magnetoresistance 300, and its extension direction is different The extension direction D of the directional magnetic resistance 300. In addition, the opposite ends of the ferromagnetic film 320 can be made into a pointed shape.

Before measuring the external magnetic field H of the anisotropic magnetoresistance 300, the magnetization direction can be set by the magnetization direction setting element (for example, the first magnetization direction setting element M1 or the second magnetization direction setting element M2 in FIG. 1). , Where the magnetization direction setting element is, for example, a coil, wire, metal sheet or conductor that can generate a magnetic field by energization. In FIG. 3A, the magnetization direction setting element can generate a magnetic field along the extension direction D by energization, so that the anisotropic magnetoresistance 300 has a magnetization direction M.

Next, the magnetization direction setting element is not energized, so that the anisotropic magnetoresistance 300 starts to measure the external magnetic field H. When there is no external magnetic field H, the magnetization direction M of the anisotropic magnetoresistor 300 is maintained in the extension direction D. At this time, a current i is applied to cause the current i to flow from the left end to the right end of the anisotropic magnetoresistor 300, which is a short circuit. The direction of the current i near the bar 310 will be perpendicular to the extension direction of the shorting bar 310, so that the current i near the shorting bar 310 flows 45 degrees with the magnetization direction M. At this time, the resistance value of the anisotropic magnetoresistance 300 is R.

When an external magnetic field H faces a direction perpendicular to the extension direction D, the magnetization direction M of the anisotropic magnetoresistance 300 will be deflected to the direction of the external magnetic field H, so that the angle between the magnetization direction and the direction of current i near the shorting bar is greater than At 45 degrees, at this time, the resistance value of the anisotropic magnetoresistance 300 changes by -ΔR, that is, it becomes R-ΔR, that is, the resistance value becomes smaller, where ΔR is greater than zero.

However, as shown in FIG. 3B, when the extension direction of the shorting bar 310 in FIG. 3B is set at 90 degrees to the extension direction of the shorting bar 310 in FIG. 3A (at this time, the extension direction of the shorting bar 310 in FIG. 3B is still It is 45 degrees with the extension direction D of the anisotropic magnetoresistance 300), and when there is an external magnetic field H, in addition, the magnetic field H will still deflect the magnetization direction M to the direction of the external magnetic field H. At this time, the magnetization direction M is short-circuited The angle of the current i flowing near the rod 310 will be less than 45 degrees, so the resistance value of the anisotropic magnetoresistor 300 will become R+ΔR, that is, the resistance value of the anisotropic magnetoresistor 300 will become larger.

In addition, when the magnetization direction M of the anisotropic magnetoresistor 300 is set to the reverse direction shown in FIG. 3A by the magnetization direction setting element, the resistance value of the anisotropic magnetoresistor 300 in FIG. 3A under the external magnetic field H will change Becomes R+ΔR. Furthermore, when the magnetization direction M of the anisotropic magnetoresistor 300 is set to the reverse direction as shown in FIG. 3B by the magnetization direction setting element, the resistance value of the anisotropic magnetoresistor 300 in FIG. 3B under the external magnetic field H is thereafter Will become R-ΔR.

Based on the above, when the setting direction of the shorting bar 310 changes, the resistance value R of the anisotropic magnetoresistance 300 corresponding to the change of the external magnetic field H will change from +ΔR to -ΔR or vice versa, and when the magnetization direction setting element is set When the set magnetization direction M is changed to the reverse direction, the resistance value R of the anisotropic magnetoresistance 300 corresponding to the change of the external magnetic field H will change from +ΔR to -ΔR or vice versa. When the direction of the external magnetic field H is reversed, the resistance value R of the anisotropic magnetoresistance 300 corresponding to the change of the external magnetic field H will change from +ΔR to -ΔR or vice versa. However, when the current i passing through the anisotropic magnetoresistance 300 becomes reversed, the resistance value R of the anisotropic magnetoresistance 300 maintains the same sign as before in response to the change in the external magnetic field H, that is, if it was originally +ΔR , It is still +ΔR after changing the direction of current, if it was originally -ΔR, it is still -ΔR after changing the direction of current.

According to the above principles, the anisotropic magnetization direction M can be determined by designing the extension direction of the shorting bar 310 or the magnetization direction M set by the magnetization direction setting element when the anisotropic magnetoresistance 300 receives a certain component of the external magnetic field H The direction of change of the resistance value R of the magnetic resistance 300, that is, the resistance value R becomes larger or smaller, for example, the amount of change is +ΔR or -ΔR.

4A and 4B illustrate the magnetization direction of the anisotropic magnetoresistance at the first time and the second time of the current sensor of FIG. 1 and the resistance value changes thereafter, respectively, and illustrate the first to eighth anomalies The extension direction of the shorting bar in the directional magnetoresistance R1 to R8. 4A and 4B, in this embodiment, the extension direction of the first to eighth anisotropic magnetoresistor R1 to R8 is the second direction D2, and the extension direction of the shorting bar 310 is as shown in FIG. 4A It is shown that it is sandwiched by 45 degrees with the second direction D2 in two different directions, and the two different directions are parallel to the plane constructed by the first direction D1 and the second direction D2.

When the wire 110 is supplied with a current I (as shown in FIG. 1), the directions of the current I1 in the first conductive section C1 and the current I2 in the second conductive section C2 are, for example, the second direction D2 and the first direction, respectively. The two directions are the opposite of D2. At this time, the current I1 generates a magnetic field component HC along the first direction D1 on the first to fourth anisotropic magnetic resistors R1 to R4, and the current I2 is on the fifth to eighth anisotropic magnetic resistors R5 to R8. A magnetic field component HC in a direction opposite to the first direction D1 is generated. In this embodiment, the magnitude of the current I1 is equal to the magnitude of the current I2. In addition, in this embodiment, when the current I flows through the wire 110, the flow direction of the current I in the first conductive section C1 (that is, the flow direction of the current I1) is opposite to the flow direction in the second conductive section C2 (that is, the current I2).的流向). In addition, in this embodiment, the component of the magnetic field generated at the first anisotropic magnetoresistance unit 222 and the second anisotropic magnetoresistance unit 224 in the first direction D1 when the current I1 flows through the first conductive segment C1 (That is, the magnetic field component HC on the left side of FIGS. 4A and 4B, which faces the first direction D1) is opposite to that when the current I2 flows through the second conductive section C2, the third anisotropic magnetoresistive unit 226 and the fourth anisotropic The direction of the component of the magnetic field generated at the magnetic resistance unit 228 in the first direction D1 (that is, the magnetic field component HC on the right in FIGS. 4A and 4B, which faces the opposite direction of the first direction D1).

At a first time, the first magnetization direction setting element M1 sets the magnetization direction M13 of the first anisotropic magnetic resistance R1 and the third anisotropic magnetic resistance R3 to the opposite direction of the second direction D2, and sets the second different The magnetization direction M24 of the directional magnetic resistance R2 and the fourth anisotropic magnetic resistance R4 is set to the second direction D2. In addition, at the first time, the second magnetization direction setting element M2 sets the magnetization direction M57 of the fifth anisotropic magnetic resistance R5 and the seventh anisotropic magnetic resistance R7 to the opposite direction of the second direction D2, and sets the sixth The magnetization direction M68 of the anisotropic magnetic resistance R6 and the eighth anisotropic magnetic resistance R8 is set to the second direction D2. In this embodiment, the first magnetization direction setting element M1 and the second magnetization direction setting element M2 are, for example, conductive coils, wires, conductive sheets (for example, metal sheets), or conductors that can generate a magnetic field by energization, as long as they can generate along The conductive structure of the magnetic field in the magnetization directions M13, M24, M57, and M68 can be used as the first magnetization direction setting element M1 and the second magnetization direction setting element M2.

After the first time, the first magnetization direction setting element M1 and the second magnetization direction setting element M2 will stop generating magnetic fields. For example, the first magnetization direction setting element M1 and the second magnetization direction setting element M2 will no longer be energized. Magnetic field. At this time, the first to fourth anisotropic magnetoresistances R1 to R4 can induce the magnetic field component HC generated by the current I1 to generate -ΔR, -ΔR, +ΔR, and +ΔR resistance changes, respectively, and The fifth to eighth anisotropic magnetic resistors R5 to R8 can induce the magnetic field component HC generated by the current I2 to generate resistance changes of +ΔR, +ΔR, -ΔR, and -ΔR, respectively.

In this embodiment, the first anisotropic magnetic resistance R1, the second anisotropic magnetic resistance R2, the sixth anisotropic magnetic resistance R6, and the fifth anisotropic magnetic resistance R5 can be connected in series from the contact point P1 to Contact point P2, contact point P3 can be electrically connected to the conductive path between the second anisotropic magnetic resistance R2 and the sixth anisotropic magnetic resistance R6, the third anisotropic magnetic resistance R3 and the fourth anisotropic magnetic resistance The resistor R4 can be connected in series from the connection point P1 to the connection point P4, and the seventh anisotropic magnetic resistance R7 and the eighth anisotropic magnetic resistance R8 can be connected in series from the connection point P2 to the connection point P5. The contact P3 can receive the reference voltage VDD, and the contact P4 and the contact P5 can be coupled to ground. At this time, the voltage difference between the contact P1 and the contact P2 in the Wheatstone bridge formed will be (VDD)×(ΔR/R), it can be an output signal, this output signal is a differential signal, and its magnitude will correspond to the magnitude of the magnetic field component HC, which in turn corresponds to the magnitude of the current I flowing through the wire 110. This output signal is called the first voltage signal V ₁ . In another embodiment, the contact point P3 can also be coupled to the ground, and the contact point P4 and the contact point P5 receive the reference voltage VDD.

At a second time after this, the first magnetization direction setting element M1 sets the magnetization direction M13' of the first anisotropic magnetic resistance R1 and the third anisotropic magnetic resistance R3 to the second direction D2, and sets the second The magnetization direction M24' of the anisotropic magnetic resistance R2 and the fourth anisotropic magnetic resistance R4 is set to the opposite direction of the second direction D2. In addition, at the second time, the second magnetization direction setting element M2 sets the magnetization direction M57' of the fifth anisotropic magnetic resistance R5 and the seventh anisotropic magnetic resistance R7 to the second direction D2, and sets the sixth anisotropy The magnetization direction M68' of the linear magnetic resistance R6 and the eighth anisotropic magnetic resistance R8 is set to the opposite direction of the second direction D2.

After the second time, the first magnetization direction setting element M1 and the second magnetization direction setting element M2 will stop generating a magnetic field. At this time, the first to fourth anisotropic magnetoresistances R1 to R4 can be induced by the current I1. The magnetic field component HC generated by the resistance value changes of +ΔR, +ΔR, -ΔR, and -ΔR, and the fifth to eighth anisotropic magnetoresistance R5 to R8 can induce the magnetic field component HC generated by the current I2. Respectively produce -ΔR, -ΔR, +ΔR and +ΔR resistance value changes. The voltage difference between the contact point P1 and the contact point P2 in the Wheatstone bridge formed at this time will be (VDD)×(-ΔR/R), which can be an output signal, and this output signal is a differential signal. The magnitude will correspond to the magnitude of the magnetic field component HC, and in turn correspond to the magnitude of the current I flowing through the wire 110, and this output signal will be referred to as the second voltage signal V ₂ hereinafter.

5 is a graph showing the output voltage-current curve of the Wheatstone bridge in FIGS. 4A and 4B, and FIG. 6 shows the Wheatstone bridge in FIGS. 4A and 4B coupled to an arithmetic unit. 4A, 4B, 5 and 6, in this embodiment, the current sensor 100 further includes an arithmetic unit 400, which is electrically connected to an output terminal of the Wheatstone bridge (that is, receives the first Voltage signal V ₁ and second voltage signal V ₂ ), wherein the first magnetization direction setting element M1 and the second magnetization direction setting element M2 connect the first, second, third, and fourth anisotropic magnetoresistive units 222, 224 The magnetization direction combination of, 226 and 228 is set as a first combination (ie the combination of magnetization direction M13, magnetization direction M24, magnetization direction M57, and magnetization direction M68 as shown in Figure 4A), so that the Wheatstone bridge outputs the first The voltage signal V ₁ , and the first magnetization direction setting element M1 and the second magnetization direction setting element M2 further change the magnetization directions of the first, second, third, and fourth anisotropic magnetoresistive units 222, 224, 226, and 228 The combination is set to a second combination opposite to the first combination (ie the combination of the magnetization direction M13', the magnetization direction M24', the magnetization direction M57' and the magnetization direction M68' as shown in Fig. 4B), so that the Wheatstone bridge The second voltage signal V _{2 is} output. The arithmetic unit 400 is used to subtract the first voltage signal V ₁ and the second voltage signal V ₂ to output an output voltage signal V _out corresponding to the magnitude of the magnetic field generated by the current I. In addition, in this embodiment, the arithmetic unit 400 can also be used to add the first voltage signal V ₁ and the second voltage signal V ₂ to output an offset voltage signal V _off .

Specifically, the arithmetic unit 400 may include an arithmetic unit 410 and an arithmetic unit 420, where the arithmetic unit 410 is, for example, an adder, which is used to phase the first voltage signal V ₁ with the second voltage signal V ₂ To output the offset voltage signal V _off . In addition, the arithmetic operator 420 is, for example, a subtractor, which is used to subtract the first voltage signal V ₁ and the second voltage signal V ₂ to output an output voltage signal V _out corresponding to the magnitude of the magnetic field generated by the current I .

It can be seen from Figure 5 that there may be an offset voltage signal V _off in the output voltage-current curve of the Wheatstone bridge, and the offset voltage can be left after the first voltage signal V ₁ and the second voltage signal V ₂ are added. After the signal V _off and the first voltage signal V ₁ and the second voltage signal V ₂ are subtracted, the output voltage-current curve will pass through the point where both voltage and current are zero, so that the voltage and current are almost It is proportional to, so that the resistance change ΔR can be accurately estimated through the output voltage signal V _out .

In this embodiment, the contacts P1 to P5 and the arithmetic unit 400 exist in the substrate 210, for example, and the substrate 210 is a circuit substrate, such as a semiconductor substrate.

7, 8 and 9 respectively show the magnetization direction of the anisotropic magnetoresistance of the current sensor of FIG. 1 at the second time and the resistance value changes when it receives external magnetic field components in three different directions thereafter. Please refer to FIG. 7 first, after the first magnetization direction setting element M1 and the second magnetization direction setting element M2 complete the setting of the magnetization directions M13', M24', M57', and M68' at the second time, when there is one along the first direction When the external magnetic field component HE1 of D1 exists, the resistance value changes produced by the first to eighth anisotropic magnetoresistance R1~R8 are respectively +ΔR, +ΔR, -ΔR, -ΔR, +ΔR, +ΔR,- ΔR and -ΔR, in this way, when the contact P3 receives the reference voltage VDD, and the contact P4 and the contact P5 are coupled to the ground, the Wheatstone bridge formed at this time between the contact P1 and the contact P2 The voltage difference between will be zero.

Please refer to FIG. 8 again. After the first magnetization direction setting element M1 and the second magnetization direction setting element M2 complete the setting of the magnetization directions M13', M24', M57', and M68' at the second time, when there is one along the second direction When the external magnetic field component HE2 of D2 exists, the resistance value changes produced by the first to eighth anisotropic magnetoresistor R1 to R8 are all zero, because the second direction D2 is not the first to eighth anisotropic magnetism The direction that the resistors R1 to R8 can sense. In this way, when the contact P3 receives the reference voltage VDD and the contact P4 and the contact P5 are coupled to the ground, the voltage difference between the contact P1 and the contact P2 in the Wheatstone bridge formed at this time will be Is zero.

Please refer to FIG. 9 again. After the first magnetization direction setting element M1 and the second magnetization direction setting element M2 complete the setting of the magnetization directions M13', M24', M57', and M68' at the second time, when there is one along the third direction When the external magnetic field component HE3 of D3 exists, the resistance value changes produced by the first to eighth anisotropic magnetoresistor R1 to R8 are all zero, because the third direction D3 is not the first to eighth anisotropic magnetism The direction that the resistors R1 to R8 can sense. In this way, when the contact P3 receives the reference voltage VDD and the contact P4 and the contact P5 are coupled to the ground, the voltage difference between the contact P1 and the contact P2 in the Wheatstone bridge formed at this time will be Is zero.

That is, in this embodiment, the Wheatstone bridge corresponds to the external magnetic field component HE1 in the first direction D1 and the output voltage signal is zero, which corresponds to the external magnetic field component in the second direction D2. The voltage signal output by HE2 is zero, and the voltage signal output by HE3 corresponding to the external magnetic field component in the third direction D3 is zero. Therefore, no matter which direction the external magnetic field is in, it will not affect the sensing result of the current sensor 100 of this embodiment, that is, it will not interfere with the output voltage of the current sensor 100.

The above response of the Wheatstone bridge to the external magnetic field components HE1, HE2, and HE3 is based on the response after the second time as an example. After the first time, the element M1 and the second magnetization direction are set in the first magnetization direction. After the setting element M2 completes the setting of the magnetization directions M13, M24, M57, and M68 as shown in Fig. 4A at the first time, the first to eighth anisotropic magnetoresistance R1 to R8 react to the resistance value generated by the external magnetic field component HE1 The changes are -ΔR, -ΔR, +ΔR, +ΔR, -ΔR, -ΔR, +ΔR, and +ΔR. In this way, when the contact P3 receives the reference voltage VDD, and the contact P4 is coupled to the contact P5 When reaching the ground, the voltage difference between the contact point P1 and the contact point P2 in the Wheatstone bridge formed at this time will be zero. For the external magnetic field components HE2 and HE3, the first to eighth anisotropic magnetoresistance R1 to R8 will not be affected by them, so there will be no resistance change. Therefore, the contact point P1 in the Wheatstone bridge is connected to the The voltage difference between points P2 will still be zero. Therefore, no matter after the first time or the second time, the current sensor 100 of this embodiment will not be interfered by external magnetic fields in any direction.

In addition, the substrate 210 may also be provided with a feedback coil (feedback coil), which at least partially overlaps the first to eighth anisotropic magnetoresistor R1 to R8, as a closed-loop control (close-loop control) the use of.

To sum up, in the current sensor of the embodiment of the present invention, because the anisotropic magnetoresistance unit is connected to form a Wheatstone bridge to sense the magnetic field generated by the current in the wire, the current The sensing has high sensitivity and high accuracy. In addition, because the current sensor of the embodiment of the present invention uses the magnetic field generated by the sensing current to reverse the magnitude of the current, the anisotropic magnetoresistive unit does not directly contact the current, so it can have a lower Power consumption.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the relevant technical field can make slight changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be determined by the scope of the attached patent application.

100‧‧‧Current sensor 110‧‧‧Wire 120‧‧‧Package body 210‧‧‧Substrate 212‧‧‧First end 214‧‧‧Second end 222‧‧‧First anisotropic magnetoresistive unit 224‧‧‧The second anisotropic magnetoresistance unit 226‧‧‧The third anisotropic magnetoresistance unit 228‧‧‧The fourth anisotropic magnetoresistance unit 300‧‧‧Anisotropic magnetoresistance 310‧‧Short Rod 320‧‧‧Ferromagnetic film 400‧‧‧Calculator 410, 420‧‧‧Arithmetic operator C1‧‧‧First conductive segment C2‧‧‧Second conductive segment D‧‧‧Extending direction D1‧‧‧ One direction D2‧‧‧The second direction D3‧‧‧The third direction H‧‧‧External magnetic field HC‧‧‧Magnetic field components HE1, HE2, HE3‧‧‧External magnetic field components I, i, I1, I2‧‧ ‧Current M, M13, M13', M24, M24', M57, M57', M68, M68'‧‧‧Magnetic direction M1‧‧‧First magnetization direction setting element M2 P2, P3, P4, P5‧‧‧Contact R1‧‧‧First anisotropic magnetoresistance R2‧‧‧Second anisotropic magnetoresistance R3‧‧‧Third anisotropic magnetoresistance R4‧‧‧Second Four anisotropic magnetoresistance R5‧‧‧Fifth anisotropic magnetoresistance R6‧‧‧Sixth anisotropic magnetoresistance R7‧‧‧Seventh anisotropic magnetoresistance R8‧‧‧Eighth anisotropic magnetoresistance ΔR‧‧‧Resistance value change V ₁ ‧‧‧First voltage signal V ₂ ‧‧‧Second voltage signal V _off ‧‧‧Offset voltage signal V _out ‧‧‧Output voltage signal

FIG. 1 is a schematic top view of a current sensor according to an embodiment of the invention. Fig. 2 is a schematic cross-sectional view of the current sensor of Fig. 1 along the line A-A. 3A and 3B are used to illustrate the operation principle of the anisotropic magnetoresistance in FIG. 1. 4A and 4B respectively show the magnetization direction of the anisotropic magnetoresistance at the first time and the second time of the current sensor of FIG. 1 and the resistance change thereafter. Fig. 5 is a graph showing output voltage-current curves of the Wheatstone bridge in Figs. 4A and 4B. FIG. 6 shows the Wheatstone bridge of FIGS. 4A and 4B coupled to an arithmetic unit. 7, 8 and 9 respectively show the magnetization direction of the anisotropic magnetoresistance of the current sensor of FIG. 1 at the second time and the resistance value changes when it receives external magnetic field components in three different directions thereafter.

100‧‧‧Current Sensor

110‧‧‧Wire

120‧‧‧Package

210‧‧‧Substrate

212‧‧‧First end

214‧‧‧Second end

222‧‧‧The first anisotropic magnetoresistance unit

224‧‧‧Second Anisotropic Magnetoresistance Unit

226‧‧‧The third anisotropic magnetoresistance unit

228‧‧‧Fourth anisotropic magnetoresistance unit

C1‧‧‧First conductive section

C2‧‧‧Second conductive section

D1‧‧‧First direction

D2‧‧‧Second direction

D3‧‧‧ Third party

I‧‧‧Current

M1‧‧‧First magnetization direction setting element

M2‧‧‧Second magnetization direction setting element

R1‧‧‧First anisotropic magnetoresistance

R2‧‧‧Second Anisotropic Magnetoresistance

R3‧‧‧The third anisotropic magnetoresistance

R4‧‧‧Fourth anisotropic magnetoresistance

R5‧‧‧Fifth anisotropic magnetoresistance

R6‧‧‧The sixth anisotropic magnetoresistance

R7‧‧‧The seventh anisotropic magnetoresistance

R8‧‧‧Eighth Anisotropic Magnetoresistance

Claims (9)

A current sensor, comprising: a substrate; a wire, having a first conductive section and a second conductive section, wherein the first conductive section and the second conductive section are arranged in a first direction, each along A second direction extends and is respectively disposed under a first end and a second end opposite to the substrate; a first anisotropic magnetoresistance unit and a second anisotropic magnetoresistance unit are disposed on the substrate Above the first end of the substrate and arranged along the first direction; a third anisotropic magnetoresistance unit and a fourth anisotropic magnetoresistance unit are arranged above the second end of the substrate and along the Arranged in the opposite direction of the first direction; a first magnetization direction setting element for setting the magnetization directions of the first anisotropic magnetoresistance unit and the second anisotropic magnetoresistance unit; and a second magnetization direction setting Element for setting the magnetization directions of the third anisotropic magnetoresistive unit and the fourth anisotropic magnetoresistive unit, wherein when a current flows through the wire, the magnetic field generated by the current is induced The change in resistance value generated by the first anisotropic magnetoresistive unit is opposite to the change in resistance value generated by the second anisotropic magnetoresistance unit, and the change in resistance value generated by the third anisotropic magnetoresistance unit is opposite to The resistance value generated by the fourth anisotropic magnetoresistive unit changes, and the first, second, third, and fourth anisotropic magnetoresistive units are electrically connected to form a Wheatstone bridge to output corresponding to the The first, second, third, and fourth anisotropic magnetoresistive unit generates a voltage signal that changes the resistance value, wherein when the current flows through the first conductive section, the first anisotropic magnetoresistance unit The direction of the component in the first direction of the magnetic field generated at the second anisotropic magnetoresistive unit is opposite to that when the current flows through the second conductive section when the third anisotropic magnetoresistive unit and the fourth The direction of the component in the first direction of the magnetic field generated at the anisotropic magnetoresistive unit. The current sensor described in item 1 of the scope of the patent application further includes an arithmetic unit electrically connected to an output terminal of the Wheatstone bridge, wherein the first magnetization direction setting element and the second magnetization direction The setting element sets the magnetization direction combination of the first, second, third, and fourth anisotropic magnetoresistive units to a first combination, so that the Wheatstone bridge then outputs a first voltage signal, and the The first magnetization direction setting element and the second magnetization direction setting element then set the magnetization direction combination of the first, second, third and fourth anisotropic magnetoresistive units to a second combination opposite to the first combination Combined to make the Wheatstone bridge output a second voltage signal, and the arithmetic unit is used to subtract the first voltage signal from the second voltage signal to output a signal corresponding to the magnetic field generated by the current The size of the output voltage signal. According to the current sensor described in claim 2, wherein the arithmetic unit is used to add the first voltage signal and the second voltage signal to output an offset voltage signal. The current sensor according to claim 1, wherein when the current flows through the wire, the direction of the current in the first conductive section is opposite to the direction of the current in the second conductive section. The current sensor according to the first item of the scope of patent application, wherein the first direction is perpendicular to the second direction. The current sensor according to item 1 of the scope of the patent application, wherein the Wheatstone bridge corresponds to the output voltage signal of the external magnetic field component in the first direction being zero, which corresponds to the voltage signal in the second direction The voltage signal output by the external magnetic field component is zero, and the voltage signal output by the external magnetic field component corresponding to a third direction is zero, wherein the third direction is perpendicular to the first direction and the second direction. direction. According to the current sensor described in claim 1, wherein the first anisotropic magnetoresistive unit includes a first anisotropic magnetoresistance and a first anisotropic magnetoresistance arranged in sequence along the opposite direction of the second direction. Two anisotropic magnetoresistances, the second anisotropic magnetoresistance unit includes a third anisotropic magnetoresistance and a fourth anisotropic magnetoresistance arranged in sequence along a direction opposite to the second direction, the first The three-anisotropic magnetoresistive unit includes a fifth anisotropic magnetoresistance and a sixth anisotropic magnetoresistance that are sequentially arranged along the opposite direction of the second direction, and the fourth anisotropic magnetoresistance unit includes A seventh anisotropic magnetoresistance and an eighth anisotropic magnetoresistance are sequentially arranged along the opposite direction of the second direction. The current sensor according to item 7 of the scope of patent application, wherein at a first time, the first magnetization direction setting element has the magnetization directions of the first anisotropic magnetoresistance and the third anisotropic magnetoresistance Set to the opposite direction of the second direction, and set the magnetization directions of the second anisotropic magnetoresistance and the fourth anisotropic magnetoresistance to the second direction; at the first time, the second magnetization direction The setting element sets the magnetization directions of the fifth anisotropic magnetic resistance and the seventh anisotropic magnetic resistance to the opposite direction of the second direction, and the sixth anisotropic magnetic resistance and the eighth anisotropy The magnetization direction of the magnetoresistance is set to the second direction; at a second time, the first magnetization direction setting element sets the magnetization directions of the first anisotropic magnetoresistance and the third anisotropic magnetoresistance Is the second direction, and the magnetization directions of the second anisotropic magnetic resistance and the fourth anisotropic magnetic resistance are set to the opposite direction of the second direction; at the second time, the second magnetization direction is set The element sets the magnetization direction of the fifth anisotropic magnetoresistance and the seventh anisotropic magnetoresistance to the second direction, and the magnetization of the sixth anisotropic magnetoresistance and the eighth anisotropic magnetoresistance The direction is set to the opposite direction of this second direction. The current sensor according to the first item of the scope of patent application, wherein the first magnetization direction setting element and the second magnetization direction setting element are conductive sheets, conductive coils, wires or conductors.

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