JP7851164B2 - Magnetic sensor circuit - Google Patents

Description

This invention relates to a magnetic sensor circuit.

Conventionally, in magnetic sensors using Hall elements, a technique is known to compensate for the effects of temperature changes by applying a compensating magnetic field to reduce sensitivity (see, for example, Patent Document 1).

Special Publication No. 2011-513706

The techniques described above had a problem: the drive current required to drive the coils that provide the compensating magnetic field was large. In particular, when compensation operation was performed in parallel with signal processing during normal operation, the circuit's current consumption increased significantly.

This invention has been made in view of the above circumstances, and aims to provide a magnetic sensor circuit that can generate a compensating magnetic field without increasing current consumption and can compensate for the effects of temperature changes in the Hall element.

A magnetic sensor circuit according to one aspect of the present invention comprises a Hall element that outputs a differential output voltage signal in response to a magnetic field applied to a magnetosensitive surface formed on a semiconductor substrate and a drive current; an integrated coil having a wound surface wound in a direction parallel to the surface of the semiconductor substrate and providing a compensating magnetic field to the Hall element; and a current control unit that controls the magnitude of the current flowing through the integrated coil, wherein at least a portion of the drive current flowing through the Hall element flows through the integrated coil.

According to the present invention, a compensating magnetic field can be generated without increasing current consumption, thereby compensating for the effects of temperature changes in the Hall element.

This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the first embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the second embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the third embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the fourth embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the fifth embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the sixth embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the seventh embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the eighth embodiment. This is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the ninth embodiment. This is a diagram illustrating the positional relationship between the Hall element and the integrated coil according to the embodiment. This is a circuit diagram showing an example of the operation of a magnetic sensor circuit according to the embodiment.

[Embodiment]
Several embodiments of the magnetic sensor circuit according to the present invention will be described with reference to the attached drawings.

[First Embodiment]
Figure 1 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the first embodiment. An example of the configuration of the magnetic sensor circuit 10A will be described with reference to the figure. The magnetic sensor circuit 10A is formed on a semiconductor substrate 2. As will be described later, the semiconductor substrate 2 is formed in a multilayer structure including a first wiring layer, a second wiring layer and an insulating layer. The semiconductor substrate 2 includes vias that electrically connect the first wiring layer and the second wiring layer. The magnetic sensor circuit 10A is contained within a semiconductor device that functions as a Hall sensor. The magnetic sensor circuit 10A comprises a Hall element 1, a drive transistor 21, a reference current generation circuit 31, a coil control circuit 41, a drive transistor 22, and an integrated coil 11.

The magnetic sensor circuit 10A includes two power supply terminals, power supply terminal 100 and power supply terminal 101. A first power supply voltage is supplied to power supply terminal 100. In the following description, the first power supply voltage will be referred to as voltage VDD. A second power supply voltage is supplied to power supply terminal 101. In the following description, the second power supply voltage will be referred to as voltage VSS.

The Hall element 1 has a magnetic sensing portion that includes a magnetic sensing surface for sensing intersecting magnetic fields. The magnetic sensing portion of the Hall element 1 is formed on the semiconductor substrate 2. The magnetic sensor circuit 10A, by incorporating the Hall element 1, detects the strength of the magnetic field intersecting the magnetic sensing surface of the Hall element 1. The Hall element 1 illustrated in Figure 1 is a horizontal Hall element (lateral Hall element) that has a magnetic sensing portion including a magnetic sensing surface parallel to the surface of the semiconductor substrate 2 and detects magnetic field components perpendicular to the surface of the semiconductor substrate 2. While the Hall element 1 illustrated in Figure 1 is a horizontal Hall element, it is not limited to horizontal Hall elements. The Hall element 1 may also be a vertical Hall element (vertical Hall element) that has a magnetic sensing portion including a magnetic sensing surface perpendicular to the surface of the semiconductor substrate 2 and detects magnetic field components parallel to the surface of the semiconductor substrate 2.

The Hall element 1 comprises a first drive terminal 1a, a first signal terminal 1b, a second drive terminal 1c, and a second signal terminal 1d. Current is supplied to the first drive terminal 1a from the power supply terminal 100. The current value flowing from the power supply terminal 100 to the first drive terminal 1a is controlled by the drive transistor 21. The drive transistor 21 is, for example, a P-channel type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The source of the drive transistor 21 is connected to the power supply terminal 100. The drain of the drive transistor 21 is connected to the first drive terminal 1a of the Hall element 1. The gate of the drive transistor 21 is connected to the reference current generation circuit 31.

The reference current generation circuit 31 controls the voltage applied to the gate of the drive transistor 21 by outputting a reference current control signal 301, thereby controlling the current value flowing between the source and drain of the drive transistor 21. In the following description, the current flowing from the power supply terminal 100 through the source and drain of the drive transistor 21 to the first drive terminal 1a of the Hall element 1 will be referred to as the drive current IDRV1.

The drive current IDRV1 flows to the power supply terminal 101 via the second drive terminal 1c. In this embodiment, the drive current IDRV1 flows to the power supply terminal 101 via a path that splits into either the drive current IDRV2 or the coil current Icoil. The coil current Icoil is the current flowing through the integrated coil 11. One end of the integrated coil 11 is connected to the second drive terminal 1c of the Hall element 1, and the other end is connected to the power supply terminal 101. In other words, at least a portion of the drive current IDRV1 flowing through the Hall element 1 becomes at least one of the drive current IDRV2 and the coil current Icoil.

The integrated coil 11 provides a compensating magnetic field to the Hall element 1. The integrated coil 11 is positioned so that the magnetic field lines linking the magnetic surface of the Hall element 1 penetrate its winding. Here, it is preferable that the integrated coil 11 is positioned so that the magnetic field lines efficiently link with the magnetic surface of the Hall element 1. For example, if the Hall element 1 is a horizontal Hall element as shown in Figure 1, it is preferable that the magnetic surface of the Hall element 1 and the winding surface of the integrated coil 11 overlap substantially parallel to each other in a direction perpendicular to the magnetic surface. In other words, it is preferable that the integrated coil 11 is wound in a direction in which the normal vector of the winding surface of the integrated coil 11 and the normal vector of the magnetic surface of the Hall element 1 are parallel to each other.

Furthermore, even when the Hall element 1 is a vertical Hall element, a compensating magnetic field can be provided in the same way as when the Hall element 1 is a horizontal Hall element. For example, by devising an arrangement such that the winding portion of the integrated coil 11 does not overlap with at least a portion of the magnetic-sensing portion of the Hall element 1 when viewed from a direction perpendicular to the surface of the semiconductor substrate 2, a compensating magnetic field can be provided that links the magnetic field generated by the integrated coil 11 with the magnetic-sensing surface of the Hall element 1.

The drive transistor 22 is, for example, an N-channel MOSFET. The drain of the drive transistor 22 is connected to the second drive terminal 1c of the Hall element 1. The source of the drive transistor 22 is connected to the power supply terminal 101. The gate of the drive transistor 22 is connected to the coil control circuit 41.

The drive current IDRV2 is the current flowing between the drain and source of the drive transistor 22. That is, a portion of the drive current IDRV1, which flows through the Hall element 1, flows as the drive current IDRV2 between the drain and source of the drive transistor 22. Another portion of the drive current IDRV1, which flows through the Hall element 1, flows as the coil current Icoil through the integrated coil 11. In other words, the integrated coil 11 and the drive transistor 22 are connected in parallel.

The coil control circuit 41 controls the voltage applied to the gate of the drive transistor 22 by outputting a control signal 401, thereby controlling the magnitude of the current flowing between the drain and source of the drive transistor 22. In other words, the drive transistor 22 also functions as a current control unit that controls the magnitude of the current flowing through the integrated coil 11. Note that in the following description, the voltage between the first drive terminal 1a and the second drive terminal 1c may be referred to as the drive terminal voltage VHALL.

The Hall element 1 outputs a differential output voltage signal in response to the magnetic field applied to its magnetic surface and the drive current IDRV1. The Hall element 1 outputs the differential output voltage signal, corresponding to the detected magnetic field strength, as the output voltage VOUT to the first signal terminal 1b and the second signal terminal 1d.

The differential output voltage signal output from Hall element 1 is a very weak voltage signal ranging from tens of microvolts to several millivolts. Therefore, it is difficult to ensure a sufficient signal-to-noise (S/N) ratio in the magnetic sensor circuit. Furthermore, the differential output voltage signal output from Hall element 1 increases or decreases with temperature changes. Additionally, when Hall element 1 is driven by a constant current source, the common-mode output voltage of the voltage signal output from Hall element 1 changes with temperature. This is because the signal output from Hall element 1 is a differential output voltage signal, and the common-mode output voltage of this differential output voltage signal changes significantly with temperature.

Next, the operation of the magnetic sensor circuit 10A will be explained. Due to the circuit configuration described above, the drive current IDRV1 is divided into either the drive current IDRV2 or the coil current Icoil, so the following equation (1) holds true.

Icoil=IDRV1-IDRV2...(1)

Here, the coil magnetic field Bcoil (hereinafter referred to as "coil magnetic field") generated by the integrated coil 11 is proportional to the magnitude of the coil current Icoil. Therefore, the difference between the drive currents IDRV1 and IDRV2 is determined to cancel out the magnetic offset Bos, which is the magnetic characteristic offset of the Hall element 1, and the coil current Icoil is indirectly set. Specifically, the reference current generation circuit 31 outputs a reference current control signal 301 to set the drive current IDRV1, the coil control circuit 41 outputs a control signal 401 to set the drive current IDRV2, and the coil current Icoil is set as the difference between the drive currents IDRV1 and IDRV2.

The coil current Icoil may be set during startup of the semiconductor device on which the magnetic sensor circuit 10A is formed, or during the calibration process performed in the background.

Furthermore, given the Hall electromotive force VH, magnetoelectric conversion coefficient KH, external magnetic field Bext, and magnetic offset Bos, the Hall electromotive force VH of the integrated coil 11 is expressed by the following equation (2). Also, the common-mode output voltage VCM of the Hall element 1 is expressed by equation (3).

VH=KH×(Bext-Bos+Bcoil)…(2)
VCM ≈ VHALL / 2 … (3)

[Summary of the first embodiment]
According to the embodiment described above, the magnetic sensor circuit 10A comprises a Hall element 1, an integrated coil 11, and a drive transistor 22 as a current control unit that controls the magnitude of the current flowing through the integrated coil 11. At least a portion of the drive current IDRV1 flowing through the Hall element 1 flows through the integrated coil 11 as a coil current Icoil. Therefore, according to this embodiment, it is not necessary to provide a separate current source to supply the drive current to the integrated coil 11, and the drive current IDRV1 flowing through the Hall element 1 can be reused, so a compensating magnetic field can be generated without increasing the current consumption. Furthermore, the generated compensating magnetic field can compensate for the effects of temperature changes in the Hall element.

According to this embodiment, unlike the conventional technology, it is not necessary to provide a separate current source to supply the drive current to the integrated coil 11. Therefore, a compensating magnetic field can be generated without increasing the circuit size. Furthermore, the generated compensating magnetic field can compensate for the effects of temperature changes in the Hall element.

Furthermore, according to this embodiment, the magnetic sensor circuit 10A includes a coil control circuit 41 to control the magnitude of the current flowing between the drain and source of the drive transistor 22, thereby indirectly controlling the magnitude of the current flowing through the integrated coil 11. The magnitude of the current flowing through the integrated coil 11 can be easily calculated using equation (1). Therefore, with the magnetic sensor circuit 10A, the magnitude of the current flowing through the integrated coil 11 can be calculated using a simple calculation formula, and the magnitude of the current flowing through the integrated coil 11 can be easily controlled.

Furthermore, according to the embodiment described above, a portion of the drive current IDRV1 flowing through the Hall element 1, namely the drive current IDRV2, flows between the drain and source of the drive transistor 22, while the remaining portion of the drive current IDRV1 flowing through the Hall element 1, namely the coil current Icoil, flows through the integrated coil 11. Therefore, the magnetic sensor circuit 10A adjusts the magnitude of the coil current Icoil flowing through the integrated coil 11 by adjusting the drive current IDRV2, which is a portion of the drive current IDRV1 flowing through the Hall element 1. Consequently, this embodiment allows for the suppression of current consumption.

[Second Embodiment]
Figure 2 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the second embodiment. An example of the configuration of the magnetic sensor circuit 10B will be described with reference to this figure.

The magnetic sensor circuit 10B differs from the magnetic sensor circuit 10A in that the integrated coil 11 and the drive transistor 22 are connected in series. In the magnetic sensor circuit 10B, one end of the integrated coil 11 is connected to the second drive terminal 1c, and the other end is connected to the drain of the drive transistor 22. The drain of the drive transistor 22 is connected to the integrated coil 11. The source of the drive transistor 22 is connected to the power supply terminal 101. In the description of the magnetic sensor circuit 10B, components similar to those in the magnetic sensor circuit 10A may be denoted by the same reference numerals, and their explanation may be omitted.

The magnetic sensor circuit 10B further includes a resistor 51. One end of the resistor 51 is connected to the second drive terminal 1c. The other end of the resistor 51 is connected to the power supply terminal 101. Because the resistor 51 shunts the drive current IDRV1 to the power supply terminal 101, the resistor 51 is sometimes referred to as a shunt circuit. A portion of the drive current IDRV1 flowing to the Hall element 1 flows through this shunt circuit. The current flowing through the shunt circuit is also referred to as the excess drive current IDRV3. Another portion of the drive current IDRV1 flowing to the Hall element 1 flows between the drain and source of the integrated coil 11 and the drive transistor 22. That is, the drive transistor 22 also functions as a current control unit that controls the magnitude of the current flowing through the integrated coil 11.

Next, the operation of the magnetic sensor circuit 10B will be explained. Due to the circuit configuration described above, the drive current IDRV1 is branched into the surplus drive current IDRV3 or the coil current Icoil. Since the integrated coil 11 and the drive transistor 22 are connected in series, the following equation (4) holds true.

Icoil=IDRV2...(4)

In this embodiment, the drive current IDRV2 is determined to cancel out the magnetic offset Bos, and the coil current Icoil is set directly. That is, the first embodiment differs in that the current Icoil is set indirectly, while the second embodiment sets the current Icoil directly.

Here, if the resistance value of resistor 51 is denoted as resistance value R1, the value of resistance value R1 is determined to satisfy the following equations (5) and (6). The drain-source voltage of the drive transistor 22 is shown as VDS(Tr2).

R1×IDRV3=VDS(Tr2)…(5)
IDRV1=IDRV2+IDRV3...(6)

Furthermore, the Hall electromotive force VH of the integrated coil 11 in this embodiment is the same as that given in equation (2) above.

On the other hand, the common-mode output voltage VCM of the integrated coil 11 is expressed by the following equation (7).
VCM=IDRV3×R1+VHALL/2…(7)

[Summary of the second embodiment]
According to the embodiment described above, the magnetic sensor circuit 10B includes a resistor 51 as a shunt circuit, so that a portion of the drive current IDRV1 flowing to the Hall element 1 flows as a drive current IDRV3. A potential difference is generated across the resistor 51 corresponding to the drive current IDRV3 and the resistance value of the resistor 51. Therefore, the potential of the second drive terminal 1c rises according to the drive current IDRV3 and the resistance value of the resistor 51. The potentials of the first signal terminal 1b and the second signal terminal 1d are the potential of the second drive terminal 1c plus VHALL/2, so as the potential of the second drive terminal 1c rises, the potentials of the first signal terminal 1b and the second signal terminal 1d rise.

In the magnetic sensor circuit 10A, the second drive terminal 1c is connected to the power supply terminal 101 via the integrated coil 11. Therefore, the potential of the second drive terminal 1c was close to the VSS value. When the output voltage of the Hall element 1 is input to the gate of an N-channel MOSFET, if the potential of the second drive terminal 1c is close to the VSS, the requirements for the input common-mode voltage range of the next stage become strict, making it difficult to amplify the output differential voltage. However, with the magnetic sensor circuit 10B, the potential of the second drive terminal 1c can be set to a value corresponding to the drive current IDRV3 and the resistance value of the resistor 51. Therefore, the potentials of the first signal terminal 1b and the second signal terminal 1d can be increased, making it easier to amplify the output voltage. Note that when the output voltage of the Hall element 1 is input to the gate of a P-channel MOSFET, a lower potential of the second drive terminal 1c is preferable.

[Third Embodiment]
Figure 3 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the third embodiment. An example of the configuration of the magnetic sensor circuit 10C will be described with reference to this figure.

The magnetic sensor circuit 10C differs from the magnetic sensor circuit 10B in that it includes a resistor 52 instead of the coil control circuit 41 and the drive transistor 22. In the magnetic sensor circuit 10C, one end of the resistor 52 is connected to the integrated coil 11, and the other end is connected to the power supply terminal 101. In the description of the magnetic sensor circuit 10C, components similar to those in the magnetic sensor circuit 10B may be denoted by the same reference numerals, thus omitting further explanation.

Here, resistors 51 and 52 also function as current control units that control the magnitude of the current flowing through the integrated coil 11. Resistor 51 may be referred to as the first resistor and resistor 52 as the second resistor. Resistor 51 is connected in series with the integrated coil 11 and controls the current flowing through the integrated coil. Resistor 52 is connected in parallel with the integrated coil 11 and resistor 51 and controls the current flowing through the integrated coil.

The resistor 52 may be a variable resistor. The resistance value of the resistor 52 may be determined by predetermined measurements during the manufacturing process of the magnetic sensor circuit 10C to adjust the coil current Icoil flowing through the integrated coil 11. The resistance value of the resistor 52 may also be adjusted by trimming after the resistor 52 is formed in the semiconductor manufacturing process, for example. As for the trimming method, well-known techniques such as laser trimming or Zener zapping may be used.

Furthermore, the resistance value of resistor 52 may be adjusted by control after semiconductor manufacturing. For example, the magnetic sensor circuit 10C may be equipped with multiple resistors and a switch circuit (not shown) to select the resistor 52 connected to the integrated coil 11. Specifically, the resistance value of resistor 52 may be adjusted during startup of the semiconductor device on which the magnetic sensor circuit 10C is formed, or during the execution of a calibration process performed in the background.

Furthermore, while this embodiment describes an example where the resistance value of resistor 52 is variable and the resistance value of resistor 51 is fixed, a configuration may also be adopted in which the resistance ratio of resistors 51 and 52 can be adjusted by making only resistor 51 a variable resistor, or by making both resistors 51 and 52 variable resistors.

Next, the operation of the magnetic sensor circuit 10C will be described. The magnetic sensor circuit 10C is similar to the magnetic sensor circuit 10B in that the drive current IDRV1 branches into an excess drive current IDRV3 or a coil current Icoil. However, the magnetic sensor circuit 10C differs from the magnetic sensor circuit 10B in that it adjusts the coil current Icoil by using a resistor 52 instead of a drive transistor 22. Specifically, in the magnetic sensor circuit 10C, the coil current Icoil is adjusted by the resistance ratio of the resistance values of resistor 51 and resistor 52.

If the resistance value of resistor 51 is R1 and the resistance value of resistor 52 is R2, the value of the coil current Icoil is expressed by the following equation (8).
Icoil=IDRV1×R1/(R1+R2)…(8)

[Summary of the third embodiment]
According to the embodiment described above, the magnetic sensor circuit 10C includes resistors 51 and 52 as current control units. By including resistors 51 and 52, the magnetic sensor circuit 10C adjusts the coil current Icoil by the resistance ratio of resistors 51 and 52. Therefore, in this embodiment, the coil current Icoil can be adjusted with a simple configuration.

In the magnetic sensor circuit 10C, when the coil current Icoil changes, the potential of the second drive terminal 1c changes according to the current value of the coil current Icoil and the resistance value of the resistor 52. That is, the output common-mode voltage VCM changes according to the coil current Icoil. Therefore, the magnetic sensor circuit 10C allows the potential of the second drive terminal 1c to be set to a value corresponding to the drive current IDRV3 and the resistance value of the resistor 51.

The potentials of the first signal terminal 1b and the second signal terminal 1d are equal to the potential of the second drive terminal 1c plus VHALL/2. Therefore, an increase in the potential of the second drive terminal 1c causes an increase in the potentials of the first signal terminal 1b and the second signal terminal 1d. According to the magnetic sensor circuit 10C, the potential of the second drive terminal 1c can be set to a value corresponding to the drive current IDRV3 and the resistance value of resistor 51. This allows the potentials of the first signal terminal 1b and the second signal terminal 1d to be increased, facilitating output voltage amplification. Note that when the common-mode output voltage of the Hall element 1 is input to the gate of a P-channel MOSFET, a lower potential of the second drive terminal 1c is preferable. Furthermore, in the magnetic sensor circuit 10C, the coil current Icoil is determined by the resistance ratio of resistors 51 and 52; therefore, the coil magnetic field Bcoil is not linear with respect to the resistance value.

[Fourth Embodiment]
Figure 4 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the fourth embodiment. An example of the configuration of the magnetic sensor circuit 10D will be described with reference to this figure.

The magnetic sensor circuits 10A to 10C described above all feature a single-phase integrated coil 11, and the current flowing through the integrated coil 11 was unidirectional. That is, the polarity of the magnetic field that magnetic sensor circuits 10A to 10C can generate was predetermined to either the north pole or the south pole. In such a fixed-polarity compensating magnetic field, it is possible to generate and compensate for situations where the magnetoelectric conversion characteristics of the Hall element 1 are shifted to the opposite polarity of the magnetic field that can be generated by the integrated coil 11. On the other hand, magnetic sensor circuit 10D is designed to compensate regardless of the direction in which the magnetoelectric conversion characteristics of the Hall element 1 are shifted.

The magnetic sensor circuit 10D differs from the magnetic sensor circuit 10A in that it includes integrated coil 11 and integrated coil 12 as integrated coils. In the description of the magnetic sensor circuit 10D, components similar to those in the magnetic sensor circuit 10A may be denoted by the same reference numerals, thus omitting further explanation.

The integrated coils 11 and 12 are configured to have opposite polarities by having different winding directions. In the following description, integrated coil 11 may be referred to as the first integrated coil, and integrated coil 12 as the second integrated coil. Integrated coils 11 and 12 are, for example, both positioned opposite the magnetic surface of the Hall element 1. Integrated coils 11 and 12 may also be positioned so as not to overlap in a direction perpendicular to the magnetic surface of the Hall element 1.

Furthermore, the magnetic sensor circuit 10D includes a switch 61 that switches the conduction state of the current flowing through the integrated coil 11, and a switch 62 that switches the conduction state of the current flowing through the integrated coil 12. In the following description, switch 61 may be referred to as the first switch, and switch 62 as the second switch.

One end of the integrated coil 11 is connected to the second drive terminal 1c, and the other end of the integrated coil 11 is connected to the switch 61. One end of the switch 61 is connected to the integrated coil 11, and the other end of the switch 61 is connected to the power terminal 101. One end of the integrated coil 12 is connected to the second drive terminal 1c, and the other end of the integrated coil 12 is connected to the switch 62. One end of the switch 62 is connected to the integrated coil 12, and the other end of the switch 62 is connected to the power terminal 101.

Next, the operation of the magnetic sensor circuit 10D will be described. The magnetic sensor circuit 10D switches the conduction state of switches 61 and 62 according to the required coil magnetic field polarity. Switches 61 and 62 switch their conduction state exclusively. When switch 61 is controlled to the conduction state, current flows from the second drive terminal 1c through the integrated coil 11 to the power terminal 101. When switch 61 is controlled to the conduction state, switch 62 is in a non-conductive state, and therefore no current flows through the integrated coil 12. When switch 62 is controlled to the conduction state, current flows from the second drive terminal 1c through the integrated coil 12 to the power terminal 101. When switch 62 is controlled to the conduction state, switch 61 is in a non-conductive state, and therefore no current flows through the integrated coil 11.

The conduction state of switches 61 and 62 is controlled by a control unit (not shown). The control unit (not shown) may switch the conduction state of switches 61 and 62 depending on which pole the characteristics of the semiconductor device (characteristics of the Hall element 1) on which the magnetic sensor circuit 10D is formed are shifted to. Furthermore, the conduction state of switches 61 and 62 may be switched depending on the application in which the semiconductor switches are used, or on the circuits connected downstream.

[Summary of the fourth embodiment]
According to the embodiment described above, the magnetic sensor circuit 10D comprises an integrated coil 11 and an integrated coil 12 with winding directions different from each other, and the conduction state of the integrated coil 11 and the integrated coil 12 is exclusively switched by exclusively switching the conduction state of the switches 61 and 62. Therefore, according to this embodiment, the magnetic sensor circuit 10D can provide a compensating magnetic field to either the north pole side or the south pole side. Thus, according to this embodiment, the magnetic sensor circuit 10D can compensate even if the characteristics of the semiconductor device (magnetoelectric conversion characteristics of the Hall element 1) are shifted to either pole.

[Fifth Embodiment]
Figure 5 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the fifth embodiment. An example of the configuration of the magnetic sensor circuit 10E will be described with reference to this figure.

The magnetic sensor circuit 10E differs from the magnetic sensor circuit 10D in that it includes an integrated differential coil 13 instead of the integrated coils 11 and 12. In the description of the magnetic sensor circuit 10E, components similar to those in the magnetic sensor circuit 10D may be denoted by the same reference numerals, thus omitting further explanation.

The integrated differential coil 13 is specifically a differential coil formed by differentially connecting two different coils. More specifically, the integrated differential coil 13 is a differential coil formed by differentially connecting a coil with an enlarged cross-sectional area of the winding surface of integrated coil 11 and a coil with an enlarged cross-sectional area of the winding surface of integrated coil 12.

The integrated differential coil 13 has two coils wound in different directions, with one end connected to the second drive terminal 1c serving as a common end. The cross-sectional areas of the two coils in the integrated differential coil 13 are approximately identical, and are approximately identical to the cross-sectional area of the magnetic surface of the Hall element 1. Therefore, the two coils overlap each other in a direction perpendicular to the magnetic surface of the Hall element 1. Thus, the cross-sectional area of each coil can be made approximately equivalent to the cross-sectional area of the Hall element 1. In practice, since the windings are arranged as a pattern on the semiconductor, it becomes necessary to cross the two windings on the semiconductor substrate. At the point where the two windings intersect, they are initially placed on different layers via vias, and after their patterns intersect, they are returned to the same layer via vias, thereby creating a differentially connected pattern on the semiconductor substrate.

[Summary of the Fifth Embodiment]
According to the embodiment described above, the magnetic sensor circuit 10E includes an integrated differential coil 13. The two coils of the integrated differential coil 13 overlap each other in a direction perpendicular to the magnetic sensing surface of the Hall element 1. Furthermore, the cross-sectional areas of the winding surfaces of the two coils are substantially the same. Therefore, the magnetic sensor circuit 10E ensures a large cross-sectional area for the integrated coil. Since the cross-sectional area of the integrated coil in the magnetic sensor circuit 10E is larger than that of the integrated coils 11 and 12, a large magnetic field can be generated with a small current. Therefore, the magnetic sensor circuit 10E ensures a wide adjustment range.
Furthermore, the magnetic sensor circuit 10E can apply a more uniform magnetic field to the Hall element 1 compared to the magnetic sensor circuit 10D.

[Sixth Embodiment]
Figure 6 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the sixth embodiment. An example of the configuration of the magnetic sensor circuit 10F will be described with reference to this figure.
First, let's explain the problems that the magnetic sensor circuit 10F according to the sixth embodiment aims to solve. In the magnetic sensor circuit 10E, the second drive terminal 1c is connected to the power supply terminal 101 via the integrated differential coil 13 and a switch. Since the resistance of the switch is close to zero, the voltage drop across the switch is also close to zero. Therefore, in the magnetic sensor circuit 10E, the potential of the second drive terminal 1c was close to VSS. When the output common-mode voltage of the Hall element 1 is input to the gate of an N-channel MOSFET, if the potential of the second drive terminal 1c is close to VSS, the requirements for the input common-mode voltage range of the next stage become strict, and amplification of the output differential voltage is not easy. The magnetic sensor circuit 10F aims to increase the potential of the second drive terminal 1c and facilitate amplification of the output common-mode voltage.

The magnetic sensor circuit 10F differs from the magnetic sensor circuit 10E in that it further includes a reference voltage generation circuit 71, an operational amplifier 81, and a drive transistor 23. In the description of the magnetic sensor circuit 10F, components similar to those in the magnetic sensor circuit 10E may be denoted by the same reference numerals, and their explanation may be omitted. In the following description, the reference voltage generation circuit 71, the operational amplifier 81, and the drive transistor 23 may be referred to as the reference voltage adjustment circuit. The reference voltage adjustment circuit constitutes a common-mode feedback circuit.
In the magnetic sensor circuit 10F, the integrated differential coil 13 is connected between the second drive terminal 1c of the Hall element 1 and the power supply terminal 101, and the reference voltage adjustment circuit adjusts the voltage between the integrated differential coil 13 and the power supply terminal 101 to a predetermined voltage.

The drive transistor 23 is an N-channel MOSFET. The drain of the drive transistor 23 is connected to the connection point between one end of switch 61 and one end of switch 62. The source of the drive transistor 23 is connected to the power supply terminal 101. The gate of the drive transistor 23 is connected to the output terminal of the operational amplifier 81.

The operational amplifier 81 has input/output terminals including a non-inverting input terminal (+), a non-inverting input terminal (-), and an output terminal. The non-inverting input terminal of the operational amplifier 81 is connected to the connection point between one end of switch 61 and one end of switch 62, and the connection point between the drain of the drive transistor 23. The inverting input terminal of the operational amplifier 81 is connected to the reference voltage generation circuit 71. The output terminal of the operational amplifier 81 is connected to the gate of the drive transistor 23.

The reference voltage generation circuit 71 controls the voltage VREF applied to the gate of the drive transistor 23 by outputting a common-mode reference voltage 701, thereby controlling the current value flowing between the drain and source of the drive transistor 23. The operational amplifier 81 adjusts the output voltage so that the potential of the drain terminal of the drive transistor 23 is equal to the voltage VREF, thereby adjusting the current value flowing between the drain and source of the drive transistor 23. As a result of the potential of the drain terminal of the drive transistor 23 being controlled to the voltage VREF, the potential of the second drive terminal 1c becomes approximately equal to the voltage VREF. Therefore, the reference voltage generation circuit 71 can be adjusted to facilitate amplification of the common-mode output voltage of the Hall element 1 by adjusting the value of the voltage VREF. The value of the voltage VREF is determined according to the common-mode input range of the subsequent circuit connected to the first signal terminal 1b and the second signal terminal 1d of the Hall element 1. The value of the voltage VREF is set, for example, to a voltage midway between VDD and VSS. The value of the voltage VREF is preferably set to approximately half the potential difference between VDD and VSS.

In this embodiment, an example was described in which the potential of the lower end of the integrated differential coil 13 is input to the non-inverting input terminal of the operational amplifier 81. However, the potential of the upper end of the integrated differential coil 13 may also be input to the non-inverting input terminal of the operational amplifier 81. The upper end of the integrated differential coil 13 is, for example, the connection point between the second drive terminal 1c and the integrated differential coil 13.

In this embodiment, an example was described in which the reference voltage adjustment circuit is connected between switches 61 and 62 and the power supply terminal 101. However, the reference voltage adjustment circuit may also be connected between the second drive terminal 1c and the integrated differential coil 13.

In this embodiment, an example where the reference voltage adjustment circuit is provided in the magnetic sensor circuit 10D was described as magnetic sensor circuit 10F. However, the reference voltage adjustment circuit may be provided in any of the magnetic sensor circuits 10A through 10E.

[Summary of the sixth embodiment]
According to the embodiment described above, the magnetic sensor circuit 10F further includes a reference voltage adjustment circuit to raise the potential at the connection point of switches 61 and 62. Specifically, the reference voltage adjustment circuit controls the potential at the connection point of switches 61 and 62 to be equal to the reference voltage VREF. Therefore, with the magnetic sensor circuit 10F, the potential of the second drive terminal 1c can be adjusted by adjusting the value of the reference voltage VREF. Thus, with the magnetic sensor circuit 10F, a compensating magnetic field can be generated while providing an appropriate common-mode level, taking into account the common-mode input range of the subsequent circuit connected to the output terminal of the Hall element 1 (for example, the input differential pair of an amplifier).
Furthermore, since the voltage drop across the integrated differential coil 13 is sufficiently small, the voltage drop across the integrated differential coil 13 does not affect the operation of the reference voltage adjustment circuit.

[Seventh Embodiment]
Figure 7 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the seventh embodiment. An example of the configuration of the magnetic sensor circuit 10G will be described with reference to this figure.

The magnetic sensor circuit 10G shows an example where the reference voltage adjustment circuit described in the sixth embodiment is applied to the magnetic sensor circuit 10B described in the second embodiment. The magnetic sensor circuit 10G differs from the magnetic sensor circuit 10B in that it further includes a reference voltage generation circuit 71, an operational amplifier 81, and a drive transistor 23 in place of the resistor 51. In the description of the magnetic sensor circuit 10G, components similar to those in the magnetic sensor circuit 10B or magnetic sensor circuit 10F may be denoted by the same reference numerals, thus omitting their explanation.

Furthermore, the reference voltage generation circuit 71, operational amplifier 81, and drive transistor 23 have a shunt function for the drive current IDRV1 to the power terminal 101, and may therefore be referred to as a shunt circuit. The shunt circuit in the magnetic sensor circuit 10G is connected to the connection point between the Hall element 1 and the integrated coil 11, and maintains the potential at the connection point between the Hall element 1 and the integrated coil 11 at a predetermined reference voltage. In other words, the shunt circuit in the magnetic sensor circuit 10G also functions as a reference voltage adjustment circuit. In the following description, the reference voltage generation circuit 71, operational amplifier 81, and drive transistor 23 may be referred to as a reference voltage adjustment circuit.

In the circuit configuration of the magnetic sensor circuit 10G, the connection of the reference voltage adjustment circuit differs from that of the magnetic sensor circuit 10F in that the drain of the drive transistor 23 is connected to the connection point between the second drive terminal 1c of the Hall element 1 and the integrated coil 11.

Next, the operation of the magnetic sensor circuit 10G will be described. The drive transistor 23 controls the potential of the second drive terminal 1c of the Hall element 1 to a predetermined reference voltage VREF. The surplus drive current IDRV3, which is the surplus current obtained by subtracting the coil current Icoil from the drive current IDRV1 (the drive current of the Hall element 1), is shunted to the power supply terminal 101. As a result, the upper end of the integrated coil 11 is fixed at the reference voltage VREF, and the drive transistor 22 can supply the desired coil current Icoil to the integrated coil 11.

[Summary of the seventh embodiment]
According to the embodiment described above, the magnetic sensor circuit 10G maintains the potential at the connection point between the Hall element 1 and the integrated coil 11 at a predetermined reference voltage VREF by including a shunt circuit. Therefore, with the magnetic sensor circuit 10G, the potential of the second drive terminal 1c can be adjusted by adjusting the value of the reference voltage VREF. Thus, with the magnetic sensor circuit 10G, a compensating magnetic field can be generated while providing an appropriate common-mode level, taking into account the common-mode input range of the subsequent circuit (e.g., an amplifier) connected to the output terminal of the Hall element 1.

[Eighth Embodiment]
Figure 8 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the eighth embodiment. An example of the configuration of the magnetic sensor circuit 10H will be described with reference to this figure.

The magnetic sensor circuit 10H, like the magnetic sensor circuit 10E described in the fifth embodiment, includes an integrated differential coil 13, but differs from the magnetic sensor circuit 10E in that it does not include switches 61 and 62. In the description of the magnetic sensor circuit 10H, components similar to those in the magnetic sensor circuit 10E are denoted by the same reference numerals, and their descriptions may be omitted.

Of the two coils in the integrated differential coil 13, the current flowing through one coil is denoted as coil current Icoil1, and the current flowing through the other coil is denoted as coil current Icoil2. Coil current Icoil is controlled by the drive transistor 22. The current flowing between the drain and source of the drive transistor 22 is also referred to as drive current IDRV2. The magnitude of drive current IDRV2 is controlled by the coil control circuit 41. Coil current Icoil2 is controlled by the resistor 51.

Next, the operation of the magnetic sensor circuit 10H will be described. The coil currents Icoil1 and Icoil2 are expressed by the following equations (9) and (10), respectively.

Icoil1=IDRV2...(9)
Icoil2=IDRV1-IDRV2...(10)

The magnetic sensor circuit 10H, by incorporating an integrated differential coil 13, can obtain a compensation magnetic field of the desired absolute value and polarity through the superposition of differential magnetic fields. That is, from equation (6) above, the magnetic field superimposed on the Hall element 1 is expressed by the following equation (11). Furthermore, by rearranging equation (11) as shown in equations (12) and (13), the following equation (14) can be obtained.

Bcoil=Bcoil1-Bcoil2...(11)
Bcoil=Kcoil(Icoil1-Icoil2)...(12)
Bcoil=Kcoil(IDRV2-IDRV1+IDRV2)...(13)
Bcoil=Kcoil(2×IDRV2−IDRV1)…(14)

From equation (14), it can be seen that the polarity of the coil magnetic field Bcoil changes depending on the relationship between the drive currents IDRV1 and IDRV2. That is, the coil magnetic field Bcoil is positive when equation (15) is satisfied, and negative when equation (16) is satisfied.

IDRV2>IDRV1×0.5…(15)
IDRV2<IDRV1×0.5…(16)

According to this embodiment, the magnetic sensor circuit 10H can adjust the polarity and absolute value of the coil magnetic field Bcoil by adjusting the relationship between the drive currents IDRV1 and IDRV2, and can compensate for any deviation in the polarity of the Hall element 1, whether it is towards the north or south pole.

[Summary of the 8th Embodiment]
According to the embodiment described above, the magnetic sensor circuit 10H controls the current flowing through one of the integrated differential coils 13 using the drive transistor 22. By controlling the values of the drive current IDRV1 and the drive current IDRV2, the polarity and absolute value of the coil magnetic field Bcoil can be flexibly controlled using the magnetic sensor circuit 10H. Furthermore, since switches 61 and 62 are unnecessary with the magnetic sensor circuit 10H, the circuit size can be reduced, the size of the semiconductor device can be reduced, and consequently, costs can be reduced. Also, since switches 61 and 62 are unnecessary with the magnetic sensor circuit 10H, control can be made easier.

[Ninth Embodiment]
Figure 9 is a circuit diagram showing an example of the configuration of a magnetic sensor circuit according to the ninth embodiment. An example of the configuration of the magnetic sensor circuit 10I will be described with reference to this figure.

The magnetic sensor circuit 10I has a complementary configuration in which the power supply potential and ground potential are swapped. The magnetic sensor circuit 10I will be described below as a complementary configuration of magnetic sensor circuit 10A, but it may also be a complementary configuration of each of the circuits from magnetic sensor circuit 10B to magnetic sensor circuit 10H. In the description of magnetic sensor circuit 10I, components with the same reference numerals as those in magnetic sensor circuit 10A may be denoted similarly, and their explanation may be omitted.

The magnetic sensor circuit 10I includes a drive transistor 21N in place of the drive transistor 21, and a drive transistor 22P in place of the drive transistor 22. The drive transistor 21N is an N-channel MOSFET. The drive transistor 22P is a P-channel MOSFET.

The source of the drive transistor 22P is connected to the power supply terminal 100. The gate of the drive transistor 22P is controlled by the coil control circuit 41. The drain of the drive transistor 22P is connected to one end of the integrated coil 11. The coil control circuit 41 controls the voltage applied to the gate of the drive transistor 22P by outputting a control signal 401, thereby controlling the current flowing between the source and drain of the drive transistor 22P.

One end of the integrated coil 11 is connected to the connection point between the drain of the drive transistor 22P and the first drive terminal 1a of the Hall element 1, and the other end of the integrated coil 11 is connected to the connection point between the power supply terminal 100 and the source of the drive transistor 22P. A drive current IDRV2 flows between the source and drain of the drive transistor 22P, and a coil current Icoil flows across both ends of the integrated coil 11.

The first drive terminal 1a of the Hall element 1 is connected to the connection point between one end of the integrated coil 11 and the drain of the drive transistor 22P. That is, in this embodiment, the Hall element 1 is driven by the drive current IDRV2 and the coil current Icoil.

The second drive terminal 1c of the Hall element 1 is connected to the drain of the drive transistor 21N. The drain of the drive transistor 21N is connected to the second drive terminal 1c. The gate of the drive transistor 21N is controlled by the reference current generation circuit 31. The source of the drive transistor 21N is connected to the power supply terminal 101. The reference current generation circuit 31 controls the voltage applied to the gate of the drive transistor 21N by outputting a reference current control signal 301, thereby controlling the current flowing between the drain and source of the drive transistor 21N.

[Summary of the 9th Embodiment]
According to the embodiment described above, the magnetic sensor circuit 10I employs a complementary configuration to the magnetic sensor circuit 10A by using drive transistors 21N and 22P. Similarly, a complementary configuration can be adopted for magnetic sensor circuits 10B to 10H. Therefore, the magnetic sensor circuit can be freely configured to use either an N-channel MOSFET or a P-channel MOSFET, and the configuration can be selected according to the layout of the semiconductor device. Thus, according to this embodiment, a flexible pattern layout can be achieved.

Furthermore, in each of the embodiments described above, from magnetic sensor circuit 10A to magnetic sensor circuit 10I, the Hall element 1 can also be controlled using the spinning current method.

Figure 10, which includes the four sub-figures 10(a) to 10(d), is a diagram illustrating the positional relationship between the Hall element and the integrated coil according to the embodiment. The positional relationship between the Hall element 1 and the integrated coils 11, 12, and 13 will be explained with reference to this figure.

Note that this diagram is a schematic diagram illustrating the relative positions of the coils, and the scale and numbers may differ from those in the actual structure. Furthermore, when the magnetic sensor circuits 10A and 10I are not distinguished, they may simply be referred to as "magnetic sensor circuit 10." Additionally, a semiconductor device on which the magnetic sensor circuit 10 is formed may simply be referred to as "semiconductor device."

Figure 10(a) shows an example of an integrated coil 11. The figure shows a plan view of the semiconductor device as seen in the direction of the magnetic surface. The integrated coil 11 is wound on a surface that is substantially parallel to the magnetic surface of the Hall element 1. In the example shown in the figure, since the integrated coil 11 is formed on the same layer as a semiconductor pattern, the coil pattern is wound so that the conductors do not overlap with each other within the same layer. In the example shown in the figure, the case where the number of turns N of the coil is 1.5 is illustrated. If it is necessary for the conductors to cross each other within the same layer, they may be wired to different layers via vias. In the example shown in the figure, wiring is performed using a first wiring layer and a second wiring layer. The number of turns N of the coil may be 2.5 or more.
In the example shown in the figure, the coil current Icoil flows in the direction of the arrow (clockwise). Therefore, the coil magnetic field Bcoil is generated from the near side to the far side.

Figure 10(b) shows an example of an integrated coil 11', which is a modified version of the integrated coil 11. This example differs from Figure 10(a) in that the winding direction of the integrated coil 11 is reversed.
In the example shown in the figure, the coil current Icoil flows in the direction of the arrow (counterclockwise). Therefore, the coil magnetic field Bcoil is generated from the far side towards the near side.

Figure 10(c) shows an example of a configuration that includes an integrated coil 11 and an integrated coil 12.
The integrated coil 11 and integrated coil 12 are arranged in the same layer. Therefore, in the example shown in Figure 10(c), the cross-sectional area of the coil is about half that of the examples shown in Figures 10(a) and 10(b). The windings branch from a common end (upper side in the figure), with integrated coil 11 wound counterclockwise and integrated coil 12 wound clockwise. As a result, coil current Icoil1 and coil current Icoil2 flow in the direction of the arrows. The magnetic field B1 generated by integrated coil 11 and the magnetic field B1 generated by integrated coil 12 are in opposite directions. Specifically, the magnetic field B1 generated by integrated coil 11 is from the near side to the far side, and the magnetic field B1 generated by integrated coil 12 is from the far side to the near side.
The example shown in the figure illustrates the case where the number of coil turns N is 1.5. However, the number of coil turns N may be 2.5 or more.

Figure 10(d) shows an example of an integrated differential coil 13. The integrated differential coil 13 has two differentially connected coils. Of the two coils in the integrated differential coil 13, one is wound counterclockwise and the other is wound clockwise. Since the two coils in the integrated differential coil 13 must intersect each other at least at one point, they intersect each other in three dimensions via vias and a second wiring layer. Coil current Icoil1 and coil current Icoil2 flow in the direction of the arrows, respectively. The magnetic field B1 generated by integrated coil 11 is from the near side to the far side, and the magnetic field B1 generated by integrated coil 12 is from the far side to the near side.
The example shown in the figure illustrates the case where the number of coil turns N is 1. However, the number of coil turns N may be 2 or more.

Figure 11, which includes the three sub-figures 11(a) to 11(c), is a circuit diagram showing an example of the operation of a magnetic sensor circuit according to the embodiment. An example of the operation of the magnetic sensor circuit 10 will be explained with reference to this figure.

Figure 11(a) shows the relationship between the external magnetic field Bext and the internal magnetic field Bin. First, the relationship between the external magnetic field Bext and the internal magnetic field Bin will be explained with reference to this figure. Note that the internal magnetic field Bin is the combined magnetic field of the external magnetic field Bext and the coil magnetic field Bcoil. The horizontal axis of the figure represents the external magnetic field Bext, and the vertical axis represents the internal magnetic field Bin. The figure shows the relationship between the external magnetic field Bext and the internal magnetic field Bin for the cases where the coil magnetic field Bcoil > 0, the coil magnetic field Bcoil = 0, and the coil magnetic field Bcoil < 0.

Here, the internal magnetic field Bin is the combined magnetic field of the external magnetic field Bext and the coil magnetic field Bcoil, so the following equation (17) holds true.

Bin=Bext+Bcoil…(17)

When the coil magnetic field Bcoil = 0, Bext = 0 and Bin = 0. When the coil magnetic field Bcoil > 0, Bext = 0 and Bin > 0. When the coil magnetic field Bcoil < 0, Bext = 0 and Bin < 0.

Next, referring to Figures 11(b) and 11(c), the relationship between the internal magnetic field Bin and the output voltage VOUT of the Hall element 1 is shown.

Figure 11(b) shows the magnetoelectric conversion characteristics with respect to an external magnetic field Bext when a coil magnetic field Bcoil is further applied to cancel out the magnetic offset Bos, as an example of a case where the control according to this embodiment is not applied. The Hall element 1 has linear magnetoelectric conversion characteristics as shown in the figure. For the Hall element 1 having the magnetoelectric conversion characteristics shown in Figure 11(b), from equation (17) above, when Bext = 0, Bin = Bcoil < 0 (N pole magnetic field). That is, the Hall element 1 having the magnetoelectric conversion characteristics exemplified in Figure 11(b) is equivalent to a state where the S pole magnetic field is biased, with the N pole shifted to low sensitivity and the S pole to high sensitivity.

If a misalignment like that shown in Figure 11(b) occurs, the control according to this embodiment can be used to apply an additional magnetic field to the north pole, bringing the magnetoelectric conversion characteristics of the Hall element 1 closer to symmetrical characteristics centered around 0 millitesla.

Figure 11(c) shows the magnetoelectric conversion characteristics with respect to the external magnetic field Bext when a coil magnetic field Bcoil is further applied to cancel out the magnetic offset Bos, as an example of applying the control according to this embodiment. From equation (17) above, when the magnetoelectric conversion coefficient KH is set by driving the integrated coils 11, 11', 12 or the integrated differential coil 13 so that Bcoil = -Bos, the output voltage VOUT of the Hall element 1 can be expressed as shown in the following equation (18).

VOUT=KH×Bext…(18)

Therefore, the magnetic offset Bos can be made to appear as if it has been canceled out from outside the semiconductor device.

The embodiments for carrying out the present invention have been described above using examples, but the present invention is not limited in any way to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the invention. Furthermore, the configurations described in the above embodiments and examples may be combined.

10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I...Magnetic sensor circuit 1...Hall element 1a...First drive terminal 1b...First signal terminal 1c...Second drive terminal 1d...Second signal terminal 11, 11', 12...Integrated coil 13...Integrated differential coil 21, 22, 23...Drive transistor 31...Reference current generation circuit 301...Reference current control signal 41...Coil control circuit 401...Control signal 51 52... Resistors 61, 62... Switches 71... Reference voltage generation circuit 701... Common-mode reference voltage 81... Operational amplifier 100, 101... Power supply terminals IDRV1, IDRV2... Drive current IDRV3... Excess drive current Icoil... Coil current VH... Hall electromotive force KH... Magnetoelectric conversion coefficient Bin... Magnetic flux density Bext... External magnetic field Bos... Magnetic offset Bcoil... Magnetic field VCM... Output common-mode voltage VHALL... Voltage between drive terminals

Claims (8)

A Hall element that outputs a differential output voltage signal in response to a magnetic field and drive current applied to a magnetosensitive surface formed on a semiconductor substrate,
An integrated coil having a winding surface wound in a direction parallel to the surface of the semiconductor substrate, which provides a compensating magnetic field to the Hall element,
A current control unit that controls the magnitude of the current flowing through the integrated coil,
The system includes a coil control circuit that controls the magnitude of the current flowing through the integrated coil ,
At least a portion of the drive current flowing through the Hall element is a magnetic sensor circuit flowing through the integrated coil,
The current control unit includes a transistor,
At least a portion of the current flowing through the Hall element flows between the drain and source of the transistor.
The coil control circuit controls the magnitude of the current flowing through the integrated coil by controlling the voltage applied to the gate of the transistor.
Magnetic sensor circuit. A portion of the current flowing through the Hall element flows between the drain and source of the transistor.
The magnetic sensor circuit according to claim 1 , wherein a portion of the current flowing through the Hall element flows through the integrated coil . The system further comprises a shunt circuit through which a portion of the current flowing through the Hall element flows,
A portion of the current flowing through the Hall element flows into the shunt circuit.
A portion of the current flowing through the Hall element flows between the drain and source of the transistor and through the integrated coil.
The magnetic sensor circuit according to claim 1 . The shunt circuit is connected to the connection point between the Hall element and the integrated coil, and maintains the potential at the connection point between the Hall element and the integrated coil at a predetermined reference voltage.
The magnetic sensor circuit according to claim 3 . A Hall element that outputs a differential output voltage signal in response to a magnetic field and drive current applied to a magnetosensitive surface formed on a semiconductor substrate,
An integrated coil having a winding surface wound in a direction parallel to the surface of the semiconductor substrate, which provides a compensating magnetic field to the Hall element,
The system includes a current control unit that controls the magnitude of the current flowing through the integrated coil,
At least a portion of the drive current flowing through the Hall element is a magnetic sensor circuit flowing through the integrated coil,
The integrated coil includes a first integrated coil and a second integrated coil whose winding direction is different from that of the first integrated coil.
A first switch for switching the conduction state of the current flowing through the first integrated coil,
The system further comprises a second switch for switching the conduction state of the current flowing through the second integrated coil,
The first switch and the second switch are a magnetic sensor circuit whose conduction state is switched exclusively . The magnetic sensor circuit according to claim 5, wherein the integrated coil is a differential coil formed by differentially connecting the first integrated coil and the second integrated coil. A Hall element that outputs a differential output voltage signal in response to a magnetic field and drive current applied to a magnetosensitive surface formed on a semiconductor substrate,
An integrated coil having a winding surface wound in a direction parallel to the surface of the semiconductor substrate, which provides a compensating magnetic field to the Hall element,
The system includes a current control unit that controls the magnitude of the current flowing through the integrated coil,
At least a portion of the drive current flowing through the Hall element is a magnetic sensor circuit flowing through the integrated coil,
The integrated coil is connected between the drive terminal and power terminal of the Hall element.
The system further comprises a reference voltage adjustment circuit that adjusts the potential between the integrated coil and the power terminal to a predetermined potential.
Magnetic sensor circuit. A Hall element that outputs a differential output voltage signal in response to a magnetic field and drive current applied to a magnetosensitive surface formed on a semiconductor substrate,
An integrated coil having a winding surface wound in a direction parallel to the surface of the semiconductor substrate, which provides a compensating magnetic field to the Hall element,
The system includes a current control unit that controls the magnitude of the current flowing through the integrated coil,
At least a portion of the drive current flowing through the Hall element is a magnetic sensor circuit flowing through the integrated coil ,
The current control unit,
A first resistor is connected in series with the integrated coil and controls the current flowing through the integrated coil,
The integrated coil and a second resistor connected in parallel with the first resistor are included .
Magnetic sensor circuit.