JP2019002911A - Magnetic sensor circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor circuit capable of detecting a magnetic field having two axes of sensitivity while reducing the occupied area of an amplifier circuit without using a magnetic focusing plate. A magnetic sensor circuit includes a vertical magnetic field sensor, a horizontal magnetic field sensor, a control circuit for switching and controlling a first measurement mode and a second measurement mode, a first arithmetic amplifier, a first feedback circuit, and a first. 2 Arithmetic amplifier, 2nd feedback circuit, connection circuit, impedance of 2nd switch and connection circuit to switch impedance of 1st switch and 2nd feedback circuit controlled by control circuit It is provided with at least one of the third switches for switching. [Selection diagram] Fig. 1

Description

  The present invention relates to a magnetic sensor circuit.

  Conventionally, in order to detect the rotation speed and rotation direction of various rotation mechanisms, a horizontal magnetic field applied from the outside is converted into a vertical magnetic field by using a magnetic converging plate configured in an integrated circuit. A method of detecting a horizontal magnetic field with a vertical magnetic field sensor is known (for example, Patent Document 1). Moreover, by converting a horizontal magnetic field applied from the outside into a vertical magnetic field using a magnetic converging plate configured in the integrated circuit, the vertical magnetic field and the horizontal magnetic field are detected by a vertical magnetic field sensor, and the detected vertical magnetic field is detected. And a signal indicating a horizontal magnetic field are known to be amplified using a common amplifier circuit (for example, Patent Document 2). In addition, a vertical magnetic field sensor and a horizontal magnetic field sensor are used to detect an externally applied vertical magnetic field and a horizontal magnetic field, respectively, and a signal indicating the detected vertical magnetic field and a signal indicating the horizontal magnetic field are shared. A configuration that uses and amplifies is known (for example, Patent Document 3).

JP 2009-150732 A Japanese Patent Laying-Open No. 2015-132574 US Pat. No. 7,535,215

  Here, in the techniques described in Patent Document 1 and Patent Document 2, since only the same type of sensor is used in the magnetic sensor circuit, the sensitivity of each detection axis can be made uniform. On the other hand, the lamination of the magnetic flux concentrating plate requires a special manufacturing process different from a general semiconductor manufacturing process, and it is difficult to reduce the manufacturing cost.

  Further, since the technique described in Patent Document 2 uses only the same type of sensor, it is possible to amplify the detected vertical magnetic field and horizontal magnetic field by a common amplifier circuit. On the other hand, in the technique described in Patent Document 3, since a vertical magnetic field sensor and a horizontal sensor having different magnetic field detection sensitivities are used, if an amplification circuit that amplifies a detected signal is shared, the vertical magnetic field sensitivity and horizontal magnetic field by analog processing are shared. It is difficult to align the sensitivity. As a countermeasure, there are cases where a signal amplifying circuit indicating a vertical magnetic field and a signal amplifying circuit indicating a horizontal magnetic field are individually provided. In this case, it is difficult to reduce power consumption. In addition, the vertical magnetic field sensitivity and the horizontal magnetic field sensitivity may not be corrected by analog processing, but in this case, when correction is performed in the digital processing section in the subsequent stage, the process cost increases due to the use of a fine process and the occupied area increases. Increases costs.

  The present invention has been made in view of the above problems, and does not use a magnetic converging plate, and can reduce the occupied area of the amplifier circuit and can detect a magnetic field with two-axis sensitivity. Is to provide.

The magnetic sensor circuit of the present invention includes a vertical magnetic field sensor, a horizontal magnetic field sensor, a first operational amplifier, a second operational amplifier, one output terminal of the vertical magnetic field sensor, and one input terminal of the first operational amplifier. A first switch connected between the second output terminal of the vertical magnetic field sensor and one input terminal of the second operational amplifier, and one of the horizontal magnetic field sensors. A third switch connected between the output terminal of the first operational amplifier and the one input terminal of the first operational amplifier, and between the other output terminal of the horizontal magnetic field sensor and the one input terminal of the second operational amplifier. A fourth switch connected to the first operational amplifier; a first feedback circuit connected between the output terminal of the first operational amplifier and the other input terminal; an output terminal of the second operational amplifier and the other input terminal; A second feedback circuit connected between A connection circuit connected between the other input terminal of the first operational amplifier and the other input terminal of the second operational amplifier, a first measurement mode for measuring the vertical magnetic field, and a measurement of the horizontal magnetic field A control circuit for controlling the second measurement mode, a fifth switch for switching the impedance of the first feedback circuit, a sixth switch for switching the impedance of the second feedback circuit, and the impedance of the connection circuit. At least one of the seventh switch to be switched,
In the first measurement mode, the control circuit connects the one output terminal of the vertical magnetic field sensor and the one input terminal of the first operational amplifier by the first switch, and the second switch To connect the other output terminal of the vertical magnetic field sensor and the one input terminal of the second operational amplifier, and at least any one of the fifth switch, the sixth switch, and the seventh switch. One open / close control, and in the second measurement mode, the third switch connects the one output terminal of the horizontal magnetic field sensor and the one input terminal of the first operational amplifier, and 4 switches connect the other output terminal of the horizontal magnetic field sensor and the one input terminal of the second operational amplifier, and the fifth switch, the sixth switch, and the seventh switch And controlling at least one of the opening and closing Chi.

  ADVANTAGE OF THE INVENTION According to this invention, the magnetic sensor circuit which can detect the magnetic field with which the sensitivity of 2 axis | shaft was equalized can be provided, without using a magnetic convergence board and reducing the occupation area of an amplifier circuit.

It is a figure which shows an example in which a vertical magnetic field sensor and a horizontal magnetic field sensor detect the magnetic field of a ring-shaped multipolar magnet. It is a figure which shows the magnetic sensor circuit which concerns on 1st Embodiment. It is a figure which shows the magnetic sensor circuit which concerns on 2nd Embodiment. It is a figure which shows the magnetic sensor circuit which concerns on 3rd Embodiment. It is a figure which shows the magnetic sensor circuit which concerns on 4th Embodiment. It is a figure showing the 2nd course concerning modification 1. It is a figure showing the 1st course concerning modification 2. It is a figure which shows the 1st path | route concerning the modification 3, and a 2nd path | route. It is a graph which shows the output of a vertical magnetic field sensor, and the output of a horizontal magnetic field sensor. It is a timing chart which shows operation | movement of a magnetic sensor circuit. It is a figure which shows the magnetic sensor circuit which concerns on 5th Embodiment.

[First Embodiment]
FIG. 1 is a diagram illustrating an example in which the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 detect the magnetic field of the ring-shaped multipolar magnet 500.

  The vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 are arranged at a position where a magnetic field (B shown in FIG. 1) generated from the ring-shaped multipolar magnet 500 can be detected. The vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 detect a change in the magnetic field accompanying the rotation of the ring-shaped multipolar magnet 500. In the following description, when describing the direction of the magnetic field, an XYZ orthogonal coordinate system may be used. In this XYZ orthogonal coordinate system, the Y-axis indicates the vertical direction of the surface on which the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 are disposed, and the X-axis indicates the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 are disposed. The Z-axis indicates the height direction of the surface on which the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 are arranged, that is, the vertical direction.

  Further, in the present embodiment, the ring-shaped multipolar magnet 500 rotates counterclockwise when viewed from one side of the Y axis (as viewed in the −Y direction) around a rotation axis parallel to the Y axis.

  As shown in FIGS. 1A and 1C, the vertical magnetic field sensor 1 detects a magnetic field in the vertical direction (hereinafter simply referred to as a vertical magnetic field) generated from the ring-shaped multipolar magnet 500. Further, as shown in FIGS. 1B and 1D, the horizontal magnetic field sensor 2 detects a horizontal magnetic field (hereinafter simply referred to as a horizontal magnetic field) generated from the ring-shaped multipolar magnet 500. .

  Here, since the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 have different internal structures constituting each sensor, there may be a difference in magnetic field detection sensitivity. Specifically, in the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2, the vertical magnetic field sensor 1 may have higher magnetic field detection sensitivity. In this case, the vertical magnetic field sensor 1 detects the vertical magnetic field, and the amplification factor of the output signal and the horizontal magnetic field sensor 2 detects the horizontal magnetic field, and the amplification factor of the output signal is required to have different amplification factors. It is done. In the above case, it is required that the amplification factor of the signal output from the vertical magnetic field sensor 1 be lower than the amplification factor of the signal output from the horizontal magnetic field sensor 2.

FIG. 2 is a diagram illustrating the magnetic sensor circuit 100 according to the first embodiment.
The magnetic sensor circuit 100 includes a vertical magnetic field sensor 1, a horizontal magnetic field sensor 2, a switch 11, a switch 12, a switch 13, a switch 14, a first operational amplifier 21, and a second operational amplifier 22. The control circuit 41, the comparator 51, the reference voltage circuit 52, the first latch circuit 54, the second latch circuit 55, the first feedback circuit A1, the second feedback circuit A2, and the connection circuit B. And a certain resistor R5.

  The vertical magnetic field sensor 1 includes a first terminal 1a and a second terminal 1b. The horizontal magnetic field sensor 2 includes a first terminal 2a and a second terminal 2b. The first feedback circuit A1 includes a first terminal A1a and a second terminal A1b. The second feedback circuit A2 includes a first terminal A2a and a second terminal A2b. The connection circuit B includes a first terminal Ba and a second terminal Bb. The comparator 51 includes two input terminals (a first terminal 51a and a second terminal 51b) and an output terminal.

The first terminal 1 a of the vertical magnetic field sensor 1 is connected to the non-inverting amplification terminal of the first operational amplifier 21 via the switch 11. The second terminal 1 b of the vertical magnetic field sensor 1 is connected to the non-inverting amplification terminal of the second operational amplifier 22 via the switch 12. The first terminal 2 a of the horizontal magnetic field sensor 2 is connected to the non-inverting amplification terminal of the first operational amplifier 21 via the switch 13. The second terminal 2 b of the horizontal magnetic field sensor 2 is connected to the non-inverting amplification terminal of the second operational amplifier 22 via the switch 14.
The first terminal A1a of the first feedback circuit A1 and the first terminal Ba of the connection circuit B are connected to the inverting amplification terminal of the first operational amplifier 21. The second terminal A1b of the first feedback circuit A1 and the output terminal of the first operational amplifier 21 are connected to the first terminal 51a of the comparator 51.
The first terminal A2a of the second feedback circuit A2 and the second terminal Bb of the connection circuit B are connected to the inverting amplification terminal of the second operational amplifier 22. The second terminal A2b of the second feedback circuit A2 and the output terminal of the second operational amplifier 22 are connected to the second terminal 51b of the comparator 51.
The output terminal of the comparator 51 is connected to the first latch circuit 54 and the second latch circuit 55.

Hereinafter, the operation of the magnetic sensor circuit 100 will be described.
The control circuit 41 outputs a control signal S1 to the switches 11 to 14 and controls the opening and closing. The switches 11 to 14 open and close according to the control signal S1 output from the control circuit 41, and the first operational amplifier 21 and the second operational amplifier 22, and the vertical magnetic field sensor 1 or the horizontal magnetic field sensor 2 Switch the connection. The magnetic sensor circuit 100 detects a vertical magnetic field when the vertical magnetic field sensor 1 is connected to the first operational amplifier 21 and the second operational amplifier 22, and detects a horizontal magnetic field when the horizontal magnetic field sensor 2 is connected. . Thereby, the magnetic sensor circuit 100 detects a magnetic field of two axes (vertical and horizontal in this example). The vertical magnetic field sensor 1 outputs a differential voltage corresponding to the magnitude of the detected vertical magnetic field from the first terminal 1a and the second terminal 1b. Further, the horizontal magnetic field sensor 2 outputs a differential voltage corresponding to the magnitude of the detected horizontal magnetic field from the first terminal 2a and the second terminal 2b.

  The control circuit 41 connects the vertical magnetic field sensor 1 to the first operational amplifier 21 and the second operational amplifier 22, and controls the switch 11 and the switch 12 to be closed when detecting the vertical magnetic field. 13 and the switch 14 are controlled to be in an open state. As a result, only the vertical magnetic field sensor 1 is connected to the first operational amplifier 21 and the second operational amplifier 22. In the following description, a mode in which only the vertical magnetic field sensor 1 is connected to the first operational amplifier 21 and the second operational amplifier 22 and the vertical magnetic field is measured will be referred to as a first measurement mode.

  In addition, the control circuit 41 connects the horizontal magnetic field sensor 2 to the first operational amplifier 21 and the second operational amplifier 22, and controls the switch 13 and the switch 14 to be closed to detect the horizontal magnetic field. The device 11 and the switch 12 are controlled to be opened. As a result, only the horizontal magnetic field sensor 2 is connected to the first operational amplifier 21 and the second operational amplifier 22. In the following description, a mode in which only the horizontal magnetic field sensor 2 is connected to the first operational amplifier 21 and the second operational amplifier 22 and the horizontal magnetic field is measured will be referred to as a second measurement mode.

  The control circuit 41 switches the open / close state of the switches 11 to 14 between the first measurement mode and the second measurement mode at predetermined time intervals. The predetermined time is a time during which the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 can detect a change in the magnetic field accompanying the rotation of the ring-shaped multipolar magnet 500. More specifically, the control circuit 41 switches between the first measurement mode and the second measurement mode at a speed sufficiently higher than the speed at which the ring-shaped multipolar magnet 500 rotates.

  The comparator 51 includes a differential voltage output from the first operational amplifier 21 and the second operational amplifier 22 in the first measurement mode or the second measurement mode, and a reference signal (voltage) output from the reference voltage circuit 52. Compare

For example, in the first measurement mode, when the comparator 51 compares the differential voltage with the reference signal, and the differential voltage is larger, the magnetic field detected by the vertical magnetic field sensor 1 is the positive direction of the Z axis. It is shown that it is a perpendicular magnetic field (S pole magnetic field). In the first measurement mode, when the differential voltage and the reference signal are compared by the comparator 51 and the differential voltage is smaller, the magnetic field detected by the vertical magnetic field sensor 1 is in the negative direction of the Z axis. The vertical magnetic field (N pole magnetic field).
For example, in the second measurement mode, if the comparator 51 compares the differential voltage with the reference signal, and the differential voltage is larger, the magnetic field detected by the horizontal magnetic field sensor 2 is the positive direction of the X axis. The horizontal magnetic field (N pole magnetic field). In the second measurement mode, when the differential voltage is smaller than the reference signal as a result of the comparison between the differential voltage and the reference signal, the magnetic field detected by the horizontal magnetic field sensor 2 is in the negative direction of the X axis. The horizontal magnetic field (S pole magnetic field).

The comparator 51 outputs a low level signal when the magnetic field detected by the vertical magnetic field sensor 1 is an N-pole magnetic field. The comparator 51 outputs a high-level signal when the magnetic field detected by the vertical magnetic field sensor 1 is an S-pole magnetic field. The comparator 51 outputs a low level signal when the magnetic field detected by the horizontal magnetic field sensor 2 is an N-pole magnetic field. The comparator 51 outputs a high level signal when the magnetic field detected by the horizontal magnetic field sensor 2 is an S-pole magnetic field.
The first latch circuit 54 holds the signal output from the comparator 51 in the first measurement mode. The second latch circuit 55 holds the signal output from the comparator 51 in the second measurement mode.

  Next, the connection path of the feedback circuit (first feedback circuit A1) constituting the feedback loop of the first operational amplifier 21 and the feedback circuit (second feedback circuit A2) constituting the feedback loop of the second operational amplifier 22 is controlled. A case where the amplification factor of the signal output from the vertical magnetic field sensor 1 and the amplification factor of the signal output from the horizontal magnetic field sensor 2 are changed by switching by the circuit 41 will be described.

  The first feedback circuit A1 includes a first path A1-1 and a second path A1-2 that are connected in parallel to each other between the inverting amplification terminal of the first operational amplifier 21 and the output terminal. The second feedback circuit A2 includes a first path A2-1 and a second path A2-2 that are connected in parallel with each other between the inverting amplification terminal of the second operational amplifier 22 and the output terminal.

  The first path A1-1 includes a resistor R1. The second path A1-2 includes a resistor R2 and a switch 15. The resistor R1 is connected between the first terminal A1a and the second terminal A1b. One end of the switch 15 is connected to the second terminal A1b, and the other end of the switch 15 is connected to the first terminal A1a via the resistor R2.

  The first path A2-1 includes a resistor R3. The second path A2-2 includes a resistor R4 and a switch 16. The resistor R3 is connected between the first terminal A2a and the second terminal A2b. One end of the switch 16 is connected to the second terminal A2b, and the other end of the switch 16 is connected to the first terminal A2a via the resistor R4.

  The control circuit 41 controls the switch 15 and the switch 16 to be closed in the first measurement mode. In this case, a resistor R1 and a resistor R2 are connected in parallel between the inverting amplification terminal and the output terminal of the first operational amplifier 21, and the inverting amplification terminal and the output terminal of the second operational amplifier 22 are connected to each other. Between them, the resistor R3 and the resistor R4 are connected in parallel to each other. Therefore, the amplification factor of the first operational amplifier 21 is determined by the combined resistance of the resistor R1 and the resistor R2 and the resistor R5, and the amplification factor of the second operational amplifier 22 is the combined resistance of the resistor R3 and the resistor R4. And the resistance R5.

  Moreover, the control circuit 41 controls the switch 15 and the switch 16 to the open state in the second measurement mode. In this case, only the resistor R1 is connected between the inverting amplification terminal of the first operational amplifier 21 and the output terminal. Further, only the resistor R3 is connected between the inverting amplification terminal of the second operational amplifier 22 and the output terminal. Therefore, the amplification factor of the first operational amplifier 21 is determined by the resistor R1 and the resistor R5, and the amplification factor of the second operational amplifier 22 is determined by the resistor R3 and the resistor R5.

  Here, the resistance values of the resistor R1, the resistor R2, and the resistor R5 are the amplification factors suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode. Is the resistance value. The resistance values of the resistors R3, R4, and R5 are resistance values at which the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode. It is.

  Further, the resistance values of the resistors R1 and R5 are resistance values at which the amplification factor of the first operational amplifier 21 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. is there. The resistance values of the resistors R3 and R5 are resistance values at which the amplification factor of the second operational amplifier 22 becomes an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2.

  With the above-described configuration, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 are lower in the first measurement mode than in the second measurement mode. Therefore, the amplification factor of the signal output from the vertical magnetic field sensor 1 can be made lower than the amplification factor of the signal output from the horizontal magnetic field sensor 2.

As described above, according to the magnetic sensor circuit 100 of the present embodiment, the impedance of the first feedback circuit A1 is set to the resistance R1 and the resistance R2 in the first measurement mode by switching the open / close state of the switch 15. In the second measurement mode, the impedance of the first feedback circuit A1 can be set to the resistance value of the resistor R1. Further, according to the magnetic sensor circuit 100 of the present embodiment, by switching the open / close state of the switch 16, in the first measurement mode, the impedance of the second feedback circuit A2 is the combined resistance of the resistor R3 and the resistor R4. In the second measurement mode, the impedance of the second feedback circuit A2 can be set to the value of the resistor R3.
Therefore, according to the magnetic sensor circuit 100 of the present embodiment, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 can be switched in synchronization with the switching of the measurement mode.

  In the magnetic sensor circuit 100 of the present embodiment, the switch 15 and the inverting amplification terminal of the first operational amplifier 21 are connected via a resistor R2, and the switch 16 and the inverting amplification of the second operational amplifier 22 are connected. The terminal is connected via a resistor R4. As a result, the magnetic sensor circuit 100 according to the present embodiment indicates that noise generated when the switch 15 and the switch 16 are opened and closed is directly input to the first operational amplifier 21 and the second operational amplifier 22. Can be suppressed.

[Second Embodiment]
FIG. 3 is a diagram illustrating the magnetic sensor circuit 101 according to the second embodiment.
In the second embodiment, the control circuit 41 switches the connection path connected in series with the feedback circuit, whereby the amplification factor of the signal output from the vertical magnetic field sensor 1 and the amplification factor of the signal output from the horizontal magnetic field sensor 2 are as follows. The case of changing is described. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the present embodiment, the first path A1-1 and the second path A1-2 are connected in series between the inverting amplification terminal of the first operational amplifier 21 and the output terminal. The first path A2-1 and the second path A2-2 are connected in series between the inverting amplification terminal of the second operational amplifier 22 and the output terminal.

The first path A1-1 includes a resistor R1. The second path A1-2 includes a resistor R6 and a switch 15. One end of the resistor R1 is connected to the first terminal A1a, and the other end of the resistor R1 is connected to the second path A1-2. The resistor R6 and the switch 15 are connected in parallel between one end of the resistor R1 and the second terminal A1b.
The first path A2-1 includes a resistor R3. The second path A2-2 includes a resistor R7 and a switch 16. One end of the resistor R3 is connected to the first terminal A2a, and the other end of the resistor R3 is connected to the second path A2-2. The resistor R7 and the switch 16 are connected in parallel between one end of the resistor R3 and the second terminal A2b.

  The control circuit 41 controls the switch 15 and the switch 16 to be closed in the first measurement mode. In this case, only the resistor R1 is connected between the inverting amplification terminal of the first operational amplifier 21 and the output terminal. Further, only the resistor R3 is connected between the inverting amplification terminal of the second operational amplifier 22 and the output terminal. Therefore, the amplification factor of the first operational amplifier 21 is determined by the resistor R1 and the resistor R5, and the amplification factor of the second operational amplifier 22 is determined by the resistor R3 and the resistor R5.

  In the second measurement mode, the switch 15 and the switch 16 are controlled to be opened. In this case, a resistor R1 and a resistor R6 are connected in series between the inverting amplification terminal of the first operational amplifier 21 and the output terminal, and between the inverting amplification terminal of the second operational amplifier 22 and the output terminal. A resistor R3 and a resistor R7 are connected in series. Accordingly, the amplification factor of the first operational amplifier 21 is determined by the combined resistance of the resistor R1 and the resistor R6 and the resistor R5, and the amplification factor of the second operational amplifier 22 is the combined resistance of the resistor R3 and the resistor R7. And the resistance R5.

  Here, the resistance values of the resistor R1 and the resistor R5 are resistance values at which the amplification factor of the first operational amplifier 21 is an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode. It is. The resistance values of the resistors R3 and R5 are resistance values at which the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode.

  The resistance values of the resistors R1, R5, and R6 are such that the amplification factor of the first operational amplifier 21 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. Resistance value. The resistance values of the resistors R3, R5, and R7 are resistance values at which the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. It is.

  With the above-described configuration, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 are lower in the first measurement mode than in the second measurement mode. Therefore, the amplification factor of the signal output from the vertical magnetic field sensor 1 can be made lower than the amplification factor of the signal output from the horizontal magnetic field sensor 2.

As described above, according to the magnetic sensor circuit 101 of the present embodiment, by switching the open / close state of the switch 15, in the first measurement mode, the impedance of the first feedback circuit A1 is set to the value of the resistor R1. In the two measurement mode, the impedance of the first feedback circuit A1 can be set to the value of the combined resistance of the resistor R1 and the resistor R6. Further, according to the magnetic sensor circuit 101 of the present embodiment, by switching the open / close state of the switch 16, the impedance of the second feedback circuit A2 is set to the value of the resistor R3 in the first measurement mode, and in the second measurement mode. The impedance of the second feedback circuit A2 can be the value of the combined resistance of the resistor R3 and the resistor R7.
Therefore, according to the magnetic sensor circuit 101 of the present embodiment, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 can be switched in synchronization with the switching of the measurement mode.

  In the magnetic sensor circuit 101 of the present embodiment, the switch 15 and the inverting amplification terminal of the first operational amplifier 21 are connected via a resistor R1, and the switch 16 and the inverting amplification of the second operational amplifier 22 are connected. The terminal is connected via a resistor R3. As a result, the magnetic sensor circuit 101 of the present embodiment indicates that noise generated by opening and closing the switch 15 and the switch 16 is directly input to the first operational amplifier 21 and the second operational amplifier 22. Can be suppressed.

[Third Embodiment]
FIG. 4 is a diagram illustrating the magnetic sensor circuit 102 according to the third embodiment.
In the third embodiment, a case where the amplification factor is changed by switching the connection path of the connection circuit B by the control circuit 41 will be described. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the present embodiment, the connection circuit B includes a first path B-1 connected in parallel between the inverting amplification terminal of the first operational amplifier 21 and the inverting amplification terminal of the second operational amplifier 22, and a second Route B-2. The first feedback circuit A1 includes a resistor R1, and the second feedback circuit A2 includes a resistor R3.

  The first path B-1 includes a resistor R5. The second path B-2 includes a resistor R8 and a switch 17. The resistor R5 is connected between the first terminal Ba and the second terminal Bb. One end of the switch 17 is connected to the second terminal Bb, and the other end of the switch 17 is connected to the first terminal Ba via the resistor R8.

  The control circuit 41 controls the switch 17 to the open state in the first measurement mode. In this case, only the resistor R <b> 5 is connected between the inverting amplification terminal of the first operational amplifier 21 and the inverting amplification terminal of the second operational amplifier 22. Therefore, the amplification factor of the first operational amplifier 21 is determined by the resistor R1 and the resistor R5, and the amplification factor of the second operational amplifier 22 is determined by the resistor R3 and the resistor R5.

  Further, the control circuit 41 controls the switch 17 to be closed in the second measurement mode. In this case, a resistor R5 and a resistor R8 are connected in parallel between the inverting amplification terminal of the first operational amplifier 21 and the inverting amplification terminal of the second operational amplifier 22. Accordingly, the amplification factor of the first operational amplifier 21 is determined by the combined resistance of the resistor R5 and the resistor R8 and the resistor R1, and the amplification factor of the second operational amplifier 22 is the combined resistance of the resistor R5 and the resistor R8. And the resistance R3.

  Here, the resistance values of the resistor R1 and the resistor R5 are resistance values at which the amplification factor of the first operational amplifier 21 is an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode. It is. The resistance values of the resistors R3 and R5 are resistance values at which the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode.

  The resistance values of the resistors R1, R5, and R8 are such that the amplification factor of the first operational amplifier 21 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. Resistance value. The resistance values of the resistors R3, R5, and R8 are resistance values at which the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. It is.

  With the above-described configuration, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 are lower in the first measurement mode than in the second measurement mode. Therefore, the amplification factor of the signal output from the vertical magnetic field sensor 1 can be made lower than the amplification factor of the signal output from the horizontal magnetic field sensor 2.

  The connection circuit B of the magnetic sensor circuit 102 of the present embodiment is connected to the inverting input terminal of the first operational amplifier 21 and the inverting input terminal of the second operational amplifier 22 in parallel with each other and has different impedances. The path B-1 and the second path B-2 are provided. The first path B-1 is provided with a resistor R5. The second path B-2 is provided with a resistor R8 and a switch 17. The resistor R8. The switch 17 is connected in series.

  According to the magnetic sensor circuit 102 of the present embodiment, by switching the open / close state of the switch 17, the impedance of the connection circuit B is set to the value of the resistor R5 in the first measurement mode, and the connection circuit B in the second measurement mode. Since the impedance of the first operational amplifier 21 and the second operational amplifier 22 can be switched in synchronization with the switching of the measurement mode, the impedance of the first operational amplifier 21 and the second operational amplifier 22 can be switched. it can.

  In the above description, the other end of the switch 17 is connected to the first terminal Ba (the inverting amplification terminal of the first operational amplifier 21) via the resistor R8. However, the present invention is not limited to this. One end of the switch 17 is connected to the first terminal Ba, and the other end of the switch 17 is connected to the second terminal Bb (the inverting amplification terminal of the second operational amplifier 22) via the resistor R8. May be.

[Fourth Embodiment]
FIG. 5 is a diagram showing a magnetic sensor circuit 103 according to the fourth embodiment.
In the fourth embodiment, the control circuit 41 switches the connection path connected in series with the connection circuit B, so that the signal output from the vertical magnetic field sensor 1 and the signal output from the horizontal magnetic field sensor 2 are amplified. A case of changing the above will be described. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In the present embodiment, the first path B-1 and the second path B-2 are connected in series between the inverting amplification terminal of the first operational amplifier 21 and the inverting amplification terminal of the second operational amplifier 22. The
The first path B-1 includes a resistor R5. The second path B-2 includes a resistor R9 and a switch 17. One end of the resistor R5 is connected to the first terminal Ba, and the other end of the resistor R5 is connected to the second path B-2. The resistor R9 and the switch 17 are connected in parallel between one end of the resistor R5 and the second terminal Bb.
The first feedback circuit A1 includes a resistor R1, and the second feedback circuit A2 includes a resistor R3.

  The control circuit 41 controls the switch 17 to the open state in the first measurement mode. In this case, a resistor R5 and a resistor R9 are connected in series between the inverting amplification terminal of the first operational amplifier 21 and the inverting amplification terminal of the second operational amplifier 22. Therefore, the amplification factor of the first operational amplifier 21 is determined by the combined resistance of the resistor R5 and the resistor R9 and the resistor R1, and the amplification factor of the second operational amplifier 22 is the combined resistance of the resistor R5 and the resistor R9. And the resistance R3.

  Further, the control circuit 41 controls the switch 17 to be closed in the second measurement mode. In this case, only the resistor R <b> 5 is connected between the inverting amplification terminal of the first operational amplifier 21 and the inverting amplification terminal of the second operational amplifier 22. Therefore, the amplification factor of the first operational amplifier 21 is determined by the resistor R1 and the resistor R5, and the amplification factor of the second operational amplifier 22 is determined by the resistor R3 and the resistor R5.

  Here, the resistance values of the resistor R1, the resistor R5, and the resistor R9 are suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode. It is a resistance value that becomes an amplification factor. The resistance values of the resistor R3, the resistor R5, and the resistor R9 are determined so that the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1 in the first measurement mode. Is the resistance value.

  Further, the resistance values of the resistors R1 and R5 are resistance values at which the amplification factor of the first operational amplifier 21 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. is there. Further, the resistance values of the resistors R3 and R5 are resistance values at which the amplification factor of the second operational amplifier 22 is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2 in the second measurement mode. is there.

  With the above-described configuration, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 are lower in the first measurement mode than in the second measurement mode. Therefore, the amplification factor of the signal output from the vertical magnetic field sensor 1 can be made lower than the amplification factor of the signal output from the horizontal magnetic field sensor 2.

As described above, according to the magnetic sensor circuit 103 of the present embodiment, the impedance of the connection circuit B is combined with the resistor R5 and the resistor R9 in the first measurement mode by switching the open / close state of the switch 17. In the second measurement mode, the impedance of the connection circuit B can be set to the value of the resistor R5.
Therefore, according to the magnetic sensor circuit 103 of the present embodiment, the amplification factors of the first operational amplifier 21 and the second operational amplifier 22 can be switched in synchronization with the switching of the measurement mode.

  In the above description, the other end of the switch 17 is connected to the first terminal Ba (the inverting amplification terminal of the first operational amplifier 21) via the resistor R5. However, the present invention is not limited to this. One end of the switch 17 is connected to the first terminal Ba, and the other end of the switch 17 is connected to the second terminal Bb (the inverting amplification terminal of the second operational amplifier 22) via the resistor R5. May be.

[Modification 1]
Hereinafter, a case in which two resistors are connected to both ends of a switch in the second path, a first modification according to the first embodiment and the third embodiment, and a switch in the second path will be described with reference to the drawings. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 6 is a diagram illustrating a second route according to the first modification.
As shown in FIG. 6A, in the first embodiment and the third embodiment described above, the second route A1-2, the second route A2-2, and the second route B-2 have a switch ( The case where the switch 15, the switch 16, and the switch 17) and the resistors (the resistors R 2, R 4, and R 8) are provided one by one has been described.

  In the first modification, as shown in FIG. 6B, the second path A1-2 includes a resistor R2-1 and a resistor R2-2 at both ends of the switch 15, respectively. The second path A2-2 includes a resistor R4-1 and a resistor R4-2 at both ends of the switch 16, respectively. The second path B-2 includes a resistor R8-1 and a resistor R8-2 at both ends of the switch 17, respectively.

  Here, it is preferable that the resistance value of the combined resistance of the resistor R2-1 and the resistor R2-2 connected in series matches the resistance value of the resistor R2 by controlling the switch 15 to be closed. . Moreover, it is preferable that the resistance value of the combined resistance of the resistor R4-1 and the resistor R4-2 connected in series matches the resistance value of the resistor R4 by controlling the switch 16 to be closed. Moreover, it is preferable that the resistance value of the combined resistance of the resistor R8-1 and the resistor R8-2 connected in series matches the resistance value of the resistor R8 by controlling the switch 17 to be closed.

  For example, in the first embodiment described above, noise generated by opening and closing the switch 15 and the switch 16 is superimposed on the output terminal of the first operational amplifier 21 and the output terminal of the second operational amplifier 22. The input of the next stage (in this example, the comparator 51) may be affected. According to the second path A1-2 and the second path A2-2 of the first modification, noise generated by opening and closing the switch 15 and the switch 16 is directly input to the comparator 51. Can be suppressed.

[Modification 2]
Hereinafter, the case where two resistors are connected to both ends of the switch, according to the second embodiment of the present invention and the second modification according to the fourth embodiment, will be described with reference to the drawings. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 7 is a diagram illustrating a first route according to the second modification.
As shown in FIG. 7A, in the second embodiment and the fourth embodiment described above, the first path A1-1, the first path A2-1, and the first path B-1 have a resistance (resistance) The case where one each of R1, resistor R3, and resistor R5) is provided has been described.

  In the second modification, as shown in FIG. 7B, the first feedback circuit A1 includes the resistor R1-1 and the resistor R1-2 as the first route A1-1 and the second route A1-2 (switch 15). ) At both ends. The second feedback circuit A2 and the connection circuit B are also shown in the figure.

  Here, when the switch 15 is controlled to be in the closed state, the resistance value of the combined resistance of the resistor R1-1 and the resistor R1-2 connected in series to the second path A1-2 is the resistance of the resistor R1. It is preferable to agree with the value. Further, when the switch 16 is controlled to be closed, the resistance value of the combined resistance of the resistor R3-1 and the resistor R3-2 connected in series to the second path A2-2 is the resistance value of the resistor R3. Preferably. Further, when the switch 17 is controlled to be in the closed state, the resistance value of the combined resistance of the resistor R5-1 and the resistor R5-2 connected in series to the second path B-2 is the resistance value of the resistor R5. Preferably.

  For example, in the second embodiment described above, noise generated by opening and closing the switch 15 and the switch 16 is superimposed on the output terminal of the first operational amplifier 21 and the output terminal of the second operational amplifier 22. The input of the next stage (in this example, the comparator 51) may be affected. According to the first path A <b> 1-1 and the first path A <b> 2-1 of Modification Example 2, noise generated by opening and closing the switch 15 and the switch 16 is directly input to the comparator 51. Can be suppressed.

[Modification 3]
Hereinafter, with reference to the drawings, the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the first modification, and the third modification according to the second modification, the first measurement mode, and the second measurement mode. The case where only the first route or only the second route is connected will be described.

FIG. 8 is a diagram illustrating a first route and a second route according to the third modification.
In the third modification, as shown in FIG. 8A, the first feedback circuit A1 includes the switch 15 (the switch 15-1 and the switch 15-2 shown in the figure), the first path A1-1, And a second route A1-2. The first path A1-1 includes a resistor R20, and the second path A1-2 includes a resistor R23. The second feedback circuit A2 and the connection circuit B are also shown in the figure.

  In the third modification, the switch 15, the switch 16, and the switch 17 are switches that switch the connection in the circuit to the first path or the second path. Specifically, the switch 15-1 and the switch 15-2 are switches that open and close in conjunction with each other. The same applies to the switches 16-1 and 16-2 and the switches 17-1 and 17-2.

  In the first feedback circuit A1, the control circuit 41 controls the state of the switch 15 so as to connect the first path A1-1 between the first terminal A1a and the second terminal A1b in the first measurement mode. To do. In the second measurement mode, the control circuit 41 controls the state of the switch 15 so as to connect the second path A1-2 between the first terminal A1a and the second terminal A1b. These operations are the same in the second feedback circuit A2 and the connection circuit B.

Here, the resistance values of the resistor R20, the resistor R21, and the resistor R22 are resistance values that are amplification factors suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1. The resistance values of the resistor R23, the resistor R24, and the resistor R25 are resistance values that are amplification factors suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2.
Therefore, according to the first feedback circuit A1, the second feedback circuit A2, and the connection circuit B of Modification 3, the amplification factor of the signal output from the vertical magnetic field sensor 1 is set to the amplification factor of the signal output from the horizontal magnetic field sensor 2. Can be lower.

  As shown in FIG. 8B, the first feedback circuit A1, the second feedback circuit A2, and the connection circuit B of Modification 3 are connected to both ends of the switch 15, the switch 16, and the switch 17, respectively. May be provided. Specifically, the switch 15, the switch 16, and the switch 17 may be provided with resistors R90 and R91 at both ends, respectively.

  In this case, the combined resistance of the resistor R90, the resistor R91, and the resistor R20, the combined resistance of the resistor R90, the resistor R91, and the resistor R22, the combined resistance of the resistor R90, the resistor R91, and the resistor R22 are combined. The resistance value is a resistance value having an amplification factor suitable for the amplification factor of the signal output from the vertical magnetic field sensor 1. The resistance value of the combined resistance of the resistor R90, the resistor R91, and the resistor R23, the resistance value of the combined resistor of the resistor R90, the resistor R91, and the resistor R24, and the resistance of the combined resistor of the resistor R90, the resistor R91, and the resistor R25 The value is a resistance value that is an amplification factor suitable for the amplification factor of the signal output from the horizontal magnetic field sensor 2.

  Therefore, according to the first feedback circuit A1, the second feedback circuit A2, and the connection circuit B of Modification 3, the amplification factor of the signal output from the vertical magnetic field sensor 1 is set to the amplification factor of the signal output from the horizontal magnetic field sensor 2. The noise generated when the switch 15, the switch 16, and the switch 17 are opened / closed is directly input to the first operational amplifier 21 and the second operational amplifier 22 and the comparison is performed. Direct input to the device 51 can be suppressed.

  For example, the first feedback circuit A1 may be configured to include one of the switch 15-1 and the switch 15-2. For example, when the first feedback circuit A1 includes the switch 15-1, one end of the resistor (the resistor R20 and the resistor R23) connected to the switch 15-2 is connected to the second terminal A1b. For example, when the first feedback circuit A1 includes the switch 15-2, one end of the resistor (the resistor R20 and the resistor R23) connected to the switch 15-1 is connected to the first terminal A1a. . The same applies to the second feedback circuit A2 and the connection circuit B.

Hereinafter, details of the output signal of the vertical magnetic field sensor 1 and the output signal of the horizontal magnetic field sensor 2 in which the amplification factor is adjusted in the embodiment and the modification described above with reference to the drawings will be described.
FIG. 9 is a graph showing the output signal W1 of the vertical magnetic field sensor 1 and the output signal W2 of the horizontal magnetic field sensor 2 for vertical and horizontal magnetic fields having the same intensity. FIG. 9A is a graph showing an output signal before the gain is adjusted. FIG. 9B is a graph showing the output signal after the amplification factor is adjusted.

  The signal W1 is a waveform indicating a change in voltage at the measurement point P1 (measurement point P1 illustrated in FIGS. 2 to 4) in the first measurement mode. The change in voltage at the measurement point P1 indicates a voltage value obtained by subtracting the voltage at the second terminal 51b from the voltage at the first terminal 51a. The signal W2 is a waveform indicating a change in voltage at the measurement point P1 in the second measurement mode.

  As described above, in the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2, the vertical magnetic field sensor 1 has higher magnetic field detection sensitivity. Therefore, in the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2, the output of the vertical magnetic field sensor 1 is larger even when the vertical magnetic field and the horizontal magnetic field having the same intensity are detected.

  Accordingly, the vertical magnetic field sensor 1 and the horizontal magnetic field sensor 2 are adjusted by adjusting the amplification factor between the output signal of the vertical magnetic field sensor 1 and the output signal of the horizontal magnetic field sensor 2 according to the configuration of the embodiment and the modification described above. The detection sensitivity can be made uniform.

Hereinafter, the operation of the magnetic sensor circuit associated with the transition between the first measurement mode and the second measurement mode will be described with reference to FIG.
The control circuit 41 controls the switch every predetermined time Δt, and switches the operation mode of the magnetic sensor circuit between the first measurement mode and the second measurement mode (waveform W3). In the magnetic sensor circuit, as the ring-shaped multipolar magnet 500 rotates, a vertical magnetic field (waveform W4) and a horizontal magnetic field (waveform W5) are generated.

  The differential voltage output from the vertical magnetic field sensor 1 according to the vertical magnetic field in the first measurement mode is input to the input terminal (measurement point P1) of the comparator 51, and the horizontal magnetic field sensor 2 is input to the horizontal magnetic field in the second measurement mode. The differential voltage output in response to is input (waveform W6). The comparator 51 outputs a signal indicating a vertical magnetic field in the first measurement mode, and outputs a signal indicating a horizontal magnetic field in the second measurement mode (waveform W7).

  The first latch circuit 54 holds and outputs a signal indicating the direction of the vertical magnetic field based on the signal output from the comparator 51 in the first measurement mode (waveform W8). The second latch circuit 55 holds and outputs a signal indicating the direction of the horizontal magnetic field based on the signal output from the comparator 51 in the second measurement mode (waveform W9).

  From time t0 to time t1 when time Δt elapses, the magnetic sensor circuit operates as the first measurement mode and detects a vertical magnetic field. During this time, the vertical magnetic field sensor 1 detects an N-pole vertical magnetic field. The comparator 51 outputs a low level signal indicating the N pole. The first latch circuit 54 holds the low level signal output from the comparator 51 (waveform W8: time t1).

  From time t1 to time t2 when time Δt elapses, the magnetic sensor circuit operates as the second measurement mode and detects a horizontal magnetic field. During this time, the horizontal magnetic field sensor 2 detects the horizontal magnetic field of the south pole. The comparator 51 outputs a high level signal indicating the S pole. The second latch circuit 55 holds the high level signal output from the comparator 51 (waveform W9: time t2).

From time t2 to time t3 when the time Δt elapses, the magnetic sensor circuit operates as the first measurement mode and detects a vertical magnetic field. Here, when the voltage at the measurement point P1 exceeds the reference voltage + Vop at time t25, the comparator 51 outputs a high level signal indicating the S pole. The first latch circuit 54 holds the high level signal output from the comparator 51 (waveform W8: time t3).
By repeating the above-described operation, the first latch circuit 54 outputs the detection result of the vertical magnetic field, and the second latch circuit 55 outputs the detection result of the horizontal magnetic field.

  As described above, the magnetic sensor circuit of the present invention can detect a biaxial (vertical and horizontal) magnetic field with uniform sensitivity without using a magnetic focusing plate. The magnetic sensor circuit of the present invention can reduce the area occupied by the amplifier circuit by sharing the amplifier circuit in the first measurement mode and the second measurement mode.

  In the embodiment and the modification described above, the case where the first feedback circuit A1 of the first operational amplifier 21 and the second feedback circuit A2 of the second operational amplifier 22 have the same circuit configuration has been described. It is not limited to this. For example, the magnetic sensor circuit may be configured to include either the first feedback circuit A1 or the second feedback circuit A2. In other words, the feedback circuit of the first operational amplifier 21 and the feedback circuit of the second operational amplifier 22 may have an asymmetric circuit configuration.

[Fifth Embodiment]
FIG. 11 is a diagram illustrating a magnetic sensor circuit 104 according to the fifth embodiment.
In the fifth embodiment, the first transconductance amplifier 31, the second transconductance amplifier 32, and the transimpedance amplifier 33 constitute an amplifier circuit instead of the first operational amplifier 21 and the second operational amplifier 22. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  Although the amplifier circuit of the first to fourth embodiments is a voltage feedback instrumentation amplifier, the amplifier circuit of the fifth embodiment is a current feedback instrumentation amplifier. That is, the amplifier circuit of the fifth embodiment uses the transconductance amplifier 32 to convert the signal current generated by the first transconductance amplifier 31 and the feedback voltage signal generated by the first feedback circuit A1, the second feedback circuit A2, and the connection circuit B. The feedback signal current obtained by voltage-current conversion in (5) is added at the nodes CFa and CFb.

  The first terminal 1 a of the vertical magnetic field sensor 1 is connected to the non-inverting input terminal of the first transconductance amplifier 31 via the switch 11. The second terminal 1 b of the vertical magnetic field sensor 1 is connected to the inverting input terminal of the first transconductance amplifier 31 via the switch 12. The first terminal 2 a of the horizontal magnetic field sensor 2 is connected to the non-inverting amplification terminal of the first transconductance amplifier 31 via the switch 13. The second terminal 2 b of the horizontal magnetic field sensor 2 is connected to the inverting amplification terminal of the first transconductance amplifier 31 via the switch 14.

  The first terminal A1a of the first feedback circuit A1 and the first terminal Ba of the connection circuit B are connected to the non-inverting input terminal of the second transconductance amplifier 32. The second terminal A1b of the first feedback circuit A1 and the non-inverting output terminal of the transimpedance amplifier 33 are connected to the first terminal 51a of the comparator 51.

  The first terminal A2a of the second feedback circuit A2 and the second terminal Bb of the connection circuit B are connected to the inverting input terminal of the second transconductance amplifier 32. The second terminal A2b of the second feedback circuit A2 and the inverting output terminal of the transimpedance amplifier 33 are connected to the second terminal 51b of the comparator 51.

  With the above-described configuration, the amplification factor of the current feedback instrumentation amplifier including the first transconductance amplifier 31, the second transconductance amplifier 32, and the transimpedance amplifier 33 is higher in the first measurement mode than in the second measurement mode. Will be lower. Therefore, the amplification factor of the signal output from the vertical magnetic field sensor 1 can be made lower than the amplification factor of the signal output from the horizontal magnetic field sensor 2.

  According to the magnetic sensor circuit 104 of the present embodiment, since the amplifier circuit is configured by a current feedback instrumentation amplifier, the input / output common-mode potential is different from that of the voltage feedback instrumentation amplifier. Operation is possible by setting the level. Therefore, there is an effect that it can operate at a low power supply voltage and can perform high-speed signal processing.

  In the present embodiment, the configuration in which the amplification factors of the amplifier circuits in the first measurement mode and the second measurement mode are switched by switching the impedances of the first feedback circuit A1 and the second feedback circuit A2 has been described. The third embodiment The impedance of the connection circuit B may be switched similarly to the magnetic sensor circuit 102 according to FIG.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and appropriate modifications may be made without departing from the spirit of the present invention. it can. You may combine the structure as described in each embodiment mentioned above.

DESCRIPTION OF SYMBOLS 1 ... Vertical magnetic field sensor 2 ... Horizontal magnetic field sensor 100, 101, 102, 103, 104 ... Magnetic sensor circuit 21, 22 ... Operational amplifier 31, 32 ... Transconductance amplifier 33 ... Transimpedance amplifier 41 ... Control circuit 51 ... Comparator 52 ... Reference voltage circuits 54, 55 ... Latch circuit 500 ... Ring-shaped multipolar magnets A1, A2 ... Feedback circuit B ... Connection circuit

Claims (3)

A vertical magnetic field sensor that outputs a differential voltage corresponding to the vertical magnetic field;
A horizontal magnetic field sensor that outputs a differential voltage according to the horizontal magnetic field;
A first operational amplifier;
A second operational amplifier;
A first switch connected between one output terminal of the vertical magnetic field sensor and one input terminal of the first operational amplifier;
A second switch connected between the other output terminal of the vertical magnetic field sensor and one input terminal of the second operational amplifier;
A third switch connected between one output terminal of the horizontal magnetic field sensor and the one input terminal of the first operational amplifier;
A fourth switch connected between the other output terminal of the horizontal magnetic field sensor and the one input terminal of the second operational amplifier;
A first feedback circuit connected between an output terminal of the first operational amplifier and the other input terminal;
A second feedback circuit connected between the output terminal of the second operational amplifier and the other input terminal;
A connection circuit connected between the other input terminal of the first operational amplifier and the other input terminal of the second operational amplifier;
A control circuit for controlling a first measurement mode for measuring the vertical magnetic field and a second measurement mode for measuring the horizontal magnetic field;
At least one of a fifth switch for switching the impedance of the first feedback circuit, a sixth switch for switching the impedance of the second feedback circuit, and a seventh switch for switching the impedance of the connection circuit; Prepared,
The control circuit includes:
In the first measurement mode, the first switch connects the one output terminal of the vertical magnetic field sensor and the one input terminal of the first operational amplifier, and the second switch switches the vertical magnetic field sensor. The other output terminal of the second operational amplifier is connected to the one input terminal of the second operational amplifier, and at least one of the fifth switch, the sixth switch, and the seventh switch is opened and closed. Control
In the second measurement mode, the one output terminal of the horizontal magnetic field sensor and the one input terminal of the first operational amplifier are connected by the third switch, and the horizontal magnetic field sensor is connected by the fourth switch. The other output terminal of the second operational amplifier is connected to the one input terminal of the second operational amplifier, and at least one of the fifth switch, the sixth switch, and the seventh switch is opened and closed. A magnetic sensor circuit characterized by controlling. A vertical magnetic field sensor that outputs a differential voltage corresponding to the vertical magnetic field;
A horizontal magnetic field sensor that outputs a differential voltage according to the horizontal magnetic field;
A first transconductance amplifier;
A first switch connected between one output terminal of the vertical magnetic field sensor and one input terminal of the first transconductance amplifier;
A second switch connected between the other output terminal of the vertical magnetic field sensor and the other input terminal of the first transconductance amplifier;
A third switch connected between one output terminal of the horizontal magnetic field sensor and the one input terminal of the first transconductance amplifier;
A fourth switch connected between the other output terminal of the horizontal magnetic field sensor and the other input terminal of the first transconductance amplifier;
A transimpedance amplifier in which one output terminal and one input terminal of the first transconductance amplifier are connected, and the other output terminal and the other input terminal of the first transconductance amplifier are connected;
A second transconductance amplifier in which the other input terminal and one output terminal of the transimpedance amplifier are connected, and the one input terminal and the other output terminal of the transimpedance amplifier are connected;
A first feedback circuit connected between one output terminal of the transimpedance amplifier and one input terminal of the second transconductance amplifier;
A second feedback circuit connected between the other output terminal of the transimpedance amplifier and the other input terminal of the second transconductance amplifier;
A connection circuit connected between the one input terminal and the other input terminal of the second transconductance amplifier;
A control circuit for controlling a first measurement mode for measuring the vertical magnetic field and a second measurement mode for measuring the horizontal magnetic field;
At least one of a fifth switch for switching the impedance of the first feedback circuit, a sixth switch for switching the impedance of the second feedback circuit, and a seventh switch for switching the impedance of the connection circuit; Prepared,
The control circuit includes:
In the first measurement mode, the first switch connects the one output terminal of the vertical magnetic field sensor and the one input terminal of the first transconductance amplifier, and the second switch switches the vertical magnetic field. The other output terminal of the sensor and the other input terminal of the first transconductance amplifier are connected, and at least one of the fifth switch, the sixth switch, and the seventh switch Control opening and closing,
In the second measurement mode, the third switch connects the one output terminal of the horizontal magnetic field sensor and the one input terminal of the first transconductance amplifier, and the fourth switch switches the horizontal magnetic field. The other output terminal of the sensor and the other input terminal of the first transconductance amplifier are connected, and at least one of the fifth switch, the sixth switch, and the seventh switch A magnetic sensor circuit that controls opening and closing. The control circuit includes:
Amplifying the first operational amplifier in the first measurement mode and the second measurement mode by controlling at least one of the fifth switch, the sixth switch, and the seventh switch The magnetic sensor circuit according to claim 1, wherein a rate and an amplification factor of the second operational amplifier are different from each other.

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