JPH1038988A - Integrated magnetoresistive element circuit - Google Patents

Abstract

(57) [Problem] To provide an integrated magnetoresistive element circuit capable of outputting a resistance change of the magnetoresistive element even when the magnetoresistive element varies. SOLUTION: Magnetoresistive elements 11 and 14 detect the same magnetic field change, and the resistance value changes according to the magnetic field change. , 14 change in resistance in a phase opposite to that of the change in resistance, the current mirror circuit is configured such that the other ends of the magnetoresistive elements 11 and 14 are connected to a current input end and the other end of the magnetoresistive element 12 The common terminal is connected to the output terminal, the common terminal is connected to the other end of the DC power supply 10, and the same current flows through the magnetoresistive elements 11, 12, and 14, and the voltage across the magnetoresistive element 11 is slightly changed with respect to the resistance change. The comparator 19 compares the voltage at the other end of the magnetoresistive element 14 with the voltage at the other end of the magnetoresistive element 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated magnetoresistive element circuit, and more particularly, to a circuit configuration capable of outputting a resistance change even when a magnetoresistive element has manufacturing variations.

[0002]

2. Description of the Related Art A magnetoresistive element changes its resistance by a change in a magnetic field. For example, this magnetoresistive element is disposed between a gear and a bias magnet. Changes in the magnetoresistive element, so that the resistance value of the magnetoresistive element changes.

By taking out the change in the resistance as a detection output voltage, the rotation speed of the gear can be detected. In this case, the rotation speed of the gear is detected using an integrated magnetoresistive element circuit including the magnetoresistive element. As this kind of integrated magnetoresistive element circuit, for example, Japanese Unexamined Patent Publication No.
There is one described in Japanese Patent No. 36382.

FIG. 11 shows an integrated magnetoresistive element circuit described in the above publication. The integrated magnetoresistive element circuit shown in FIG. 11 has magnetoresistive elements 11 and 13 each having one end connected to one end of DC power supply 10, collectors connected to the other ends of magnetoresistive elements 11 and 13, and Transistor 1 whose emitter is connected to the other end of DC power supply 10
It comprises a current mirror circuit composed of 5 and 17 and a comparator 19 for comparing the voltage at the other end of the magnetoresistive element 11 with the voltage at the other end of the magnetoresistive element 13.

In this integrated magnetoresistive element circuit, first, a DC power supply 10 supplies the magnetoresistive elements 11, 1
3, when the current flows, the magnetoresistive effect elements 11 and 13
Different magnetic fields are detected, and the resistance values change differently.

The transistor 1 of the current mirror circuit
5 and 17 make the current flowing through the magnetoresistive elements 11 and 13 equal. For this reason, the voltage drop between both ends of the magnetoresistive elements 11 and 13 is different.

Further, a voltage V11 at the other end of the magnetoresistive effect element 11 and a voltage V12 at the other end of the magnetoresistive effect element 13 are compared by a comparator 19 and taken out as a detection output.

In this case, since the base and the collector of the transistor 15 are directly connected, as shown in FIG. 12A, the temporal change of the voltage V11 (input voltage) is small, but the voltage V12 (input voltage) is small. The change over time of the voltage is large.

Further, since the resistances of the magnetoresistive elements 11 and 13 have substantially the same resistance in a state where no magnetic field is applied, as shown in FIG.
1 intersects, and the voltage V12 fluctuates up and down with respect to the voltage V11 by almost the same amplitude.

As a result, as shown in FIG.
At the time when the voltage V12 and the voltage V11 cross, and during the period when the voltage V11 is higher than the voltage V12, the output voltage V0
Is obtained.

[0011]

However, in the case of the conventional integrated magnetoresistive element circuit, if the resistance values and the resistance change rates of the magnetoresistive elements 11 and 13 vary, FIG. ), The voltage V11 and the voltage V
12 are completely separated from each other and no longer intersect.

In such a case, as shown in FIG. 13 (b), the output voltage V0 cannot be obtained, and for example, the rotation speed of the gear cannot be detected.

An object of the present invention is to provide an integrated magnetoresistive element circuit capable of outputting a change in resistance of the magnetoresistive element even when the magnetoresistive element varies.

[0014]

Means for Solving the Problems The integrated magnetoresistive element circuit of the present invention employs the following means to solve the above problems. According to the first aspect of the present invention, there are provided first and second magnetoresistive elements each having one end connected to one end of a DC power supply, each of which detects the same magnetic field change and whose resistance value changes by the magnetic field change; A third magnetic resistance in which a change in a magnetic field different from that of the second magnetoresistive element is detected, and the change in the magnetic field changes the resistance in a phase opposite to the change in the resistance of the first and second magnetoresistive elements. The other end of the effect element and the first and second magnetoresistive elements are connected to a current input end,
The other end of the third magnetoresistive element is connected to the current output terminal, the common terminal is connected to the other end of the DC power supply, and an equal current flows through the first to third magnetoresistive elements.
A current mirror circuit for slightly changing the voltage between both ends of the magnetoresistive element with respect to the resistance change, and the voltage at the other end of the second magnetoresistive element and the voltage at the other end of the third magnetoresistive element. The gist is to provide a comparison circuit for comparison.

According to the present invention, the resistance values of the first and second magnetoresistive elements change at the same value by the same magnetic field change. Further, the resistance value of the third magnetoresistive element changes in a phase opposite to that of the first and second magnetoresistive elements due to different magnetic fields.

When the current mirror circuit causes the same current to flow through the first to third magnetoresistive elements, the voltage across the first magnetoresistive element changes slightly, and the second magnetoresistive element changes. Is in phase with the voltage of the first magnetoresistive element and is higher than that voltage.

The voltage at the other end of the third magneto-resistance effect element has a phase opposite to the voltage at the other end of the second magneto-resistance effect element. Then, the comparison circuit compares the voltage at the other end of the third magnetoresistive element with the voltage at the other end of the second magnetoresistive element.

That is, the voltage at the other end of the third magnetoresistive element has a phase opposite to that of the voltage at the other end of the second magnetoresistive element, and the voltage at the other end of the second magnetoresistive element is Since the voltage at the end is a relatively large voltage, the voltage at the other end of the third magnetoresistive element crosses the voltage at the other end of the second magnetoresistive element even if the magnetoresistive element varies. The comparison circuit outputs an output signal.

Therefore, a stable output signal can be obtained even when the resistance or resistivity of the magnetoresistive element varies.

According to a second aspect of the present invention, the current mirror circuit includes a first transistor having a collector and a base connected to a first current input terminal and a second transistor having a base connected to a second current input terminal. And a third transistor having a collector connected to the current output terminal, a base connected to the base of the first transistor, and an emitter connected to the emitters of the first and second transistors. And

According to the present invention, since the first transistor has the collector and the base connected to the first current input terminal, the voltage at the other end of the first magnetoresistive element has a small amplitude, Since only the base of the second transistor is connected to the second current input terminal, the voltage at the other end of the second magnetoresistive element is a voltage having a relatively large amplitude. And the voltage at the other end of the third magnetoresistive element are output to the comparison circuit.

According to a third aspect of the present invention, the other end of the third magnetoresistive element is connected to one terminal of the comparison circuit, and the other end of the second magnetoresistive element is connected to the third magnetic element. Providing a first resistor and a second resistor connected in series between the other end of the resistance effect element and comparing the midpoint terminal connecting the first resistor and the second resistor with each other; The point is that the terminal is connected to the other terminal of the circuit.

According to the present invention, the voltage at the other end of the third magnetoresistive element is input to one terminal of the comparison circuit,
The voltage at the other end of the magnetoresistive element and the voltage at the other end of the third magnetoresistive element are divided by the first resistor and the second resistor, and the divided voltage is used as the other end of the comparison circuit. , And a comparison circuit compares the voltages to obtain an output signal.

According to a fourth aspect of the present invention, there is provided a variable resistor for varying a voltage at the midpoint terminal, between the other end of the third magnetoresistance effect element and one terminal of the comparison circuit, A difference that amplifies the voltage difference between the voltage at the other end of the third magnetoresistive element and the voltage at the midpoint terminal changed by the variable resistor, and outputs the amplified output to one terminal of the comparison circuit. And a dynamic amplifier circuit.

According to the present invention, the variable resistor varies the voltage at the midpoint terminal, and the differential amplifier circuit varies the voltage at the other end of the third magnetoresistive element and the variable resistor. Since the voltage difference from the voltage at the midpoint terminal is amplified and the amplified output is output to one terminal of the comparison circuit, the amplified output can perform stable signal processing without generating waveform distortion.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the integrated magnetoresistive element circuit of the present invention will be described in detail.

(Embodiment 1) FIG. 1 shows a configuration diagram of an integrated magnetoresistive element circuit according to Embodiment 1 of the present invention. In FIG. 1, transistors 15, 17,
Sixteen emitters are connected.

The other end of the magnetoresistive element 11 whose resistance changes with a change in the magnetic field is connected to the collector of the transistor 15, and the other end of the magnetoresistive element 14 whose resistance changes with a change in the magnetic field is connected to the collector of the transistor 16. The ends are connected.

The other end of the magnetoresistive element 12 whose resistance changes due to a change in the magnetic field different from the change in the magnetic field of the magnetoresistive elements 11 and 14 is connected to the collector of the transistor 17.

As shown in FIG. 3, the magnetoresistive elements 11, 12, and 14 are provided on an insulating substrate 8, and the insulating substrate 8 is disposed between the gear 21 and the bias magnet 23.

As shown in FIG. 4, the magnetoresistive elements 11 and 14 are arranged in the same direction, and
Since the same magnetic field is applied from 3, the change in resistance becomes the same. FIG. 5 shows the MR patterns 110 of the magnetoresistive elements 11 and 14.

On the other hand, as shown in FIG. 4, the magnetoresistive element 12 is arranged in a direction perpendicular to the directions of the magnetoresistive elements 11 and 14, and the same magnetic field is applied from the bias magnet 23. The change in the resistance value of the magnetoresistive element 12 has an opposite phase to the change in the resistance value of the magnetoresistive elements 11 and 14.

The bases of the transistors 15, 16, 17 are connected to each other. The collector and the base of the transistor 15 are directly connected. For this reason,
The voltage at the other end of the magnetoresistive element 11 is determined by the voltage between the emitter and the collector, and has a voltage waveform with a small amplitude. The transistors 15, 16, and 17 form a current mirror circuit.

The transistors 15, 16, and 17 operate so that the same current flows through the magnetoresistive elements 11, 12, and 14.

The voltage V1 at the other end of the magnetoresistive element 12 is input to the non-inverting input terminal (+) of the comparator 19 as an input voltage. The voltage V2 at the other end of the magnetoresistive element 14 is input to the inverting input terminal (-) of the comparator 19 as an input voltage.

The comparator 19 has a voltage V1 and a voltage V2.
And outputs the output voltage V0 at the time when the voltage V1 crosses and during the period when the voltage V1 is higher than the voltage V2.

Next, the operation of the first embodiment of the integrated magnetoresistive element circuit configured as described above will be described with reference to the drawings.

First, the DC power supply 10 supplies the transistor 15
Through the transistor 16, a current flows through the transistor 16 to the magnetoresistive element 14,
A current flows to the magnetoresistive element 12 through the transistor 17.

In this case, the transistors 15, 16, 17
Supplies the same current to the magnetoresistive elements 11, 12, and 14.

The magnetoresistive elements 11 and 14 are shown in FIG.
As shown in (a), the same change in the magnetic field is detected, and the resistance changes at the same value. Also, the voltage across the magnetoresistive element 11 changes slightly, and the voltage at the other end of the magnetoresistive element 14 is in phase with the voltage of the magnetoresistive element 11,
In addition, the voltage becomes higher than that voltage.

The magnetoresistance effect element 12 is arranged in a direction orthogonal to the magnetoresistance effect elements 11 and 14. For this reason, the magnetoresistive element 12 is
2A, a change in the magnetic field different from the change in the magnetic field is detected, and as shown in FIG.
The change in the resistance values of the resistors 1 and 14 is in an opposite phase.

Accordingly, the voltage at the other end of the magnetoresistive element 12 has a phase opposite to that of the voltage at the other end of the magnetoresistive element 14. Then, the comparator 19 compares the voltage at the other end of the magnetoresistive element 12 with the voltage at the other end of the magnetoresistive element 14.

That is, the voltage at the other end of the magnetoresistive element 12 has a phase opposite to that of the voltage at the other end of the magnetoresistive element 14, and the voltage at the other end of the magnetoresistive element 14 is relatively low. Since the voltage is large, the magnetoresistive element 11,
Even if 12, 14 vary, as shown in FIG.
The voltage at the other end of the magnetoresistive element 12 crosses the voltage at the other end of the magnetoresistive element 14.

As a result, as shown in FIG. 2C, the comparator 19 outputs the output voltage VO during a period when the voltage V1 is higher than the voltage V2.

As described above, the magnetoresistive elements 11, 1
Even if the resistance value or resistivity of 2, 14 varies,
Since the voltage V1 and the voltage V2 tend to overlap, a stable output signal is obtained.

(Embodiment 2) FIG. 6 shows a configuration diagram of an embodiment 2 of an integrated magnetoresistive element circuit. The integrated magnetoresistive element circuit of the second embodiment shown in FIG. 6 is different from the circuit of the first embodiment in that
Between the other end of the comparator 19 and the inverting input terminal of the comparator 19.
Is connected, and a second resistor 20b is connected between the other end of the magnetoresistive element 14 and the inverting input terminal of the comparator 19.

Further, one end of the capacitor 18 is connected to the inverting input terminal of the comparator 19, and the other end of the capacitor 18 is grounded. The resistance value of the first resistor 20a is the same as the resistance value of the second resistor 20b.

The divided voltage V3 obtained by dividing the voltage V2 of the magnetoresistive element 14 and the voltage V1 of the magnetoresistive element 12 by the first resistor 20a and the second resistor 20b is used as the input voltage. Is input to the inverting input terminal.

The comparator 19 has a voltage V1 and a voltage V3.
And outputs the output voltage V0 during the period when the voltage V1 crosses and the voltage V1 is higher than the voltage V3.

Since the other structure is the same as that of the first embodiment, the same parts are denoted by the same reference numerals and the details are omitted.

Next, the operation of the second embodiment of the integrated magnetoresistive element circuit configured as described above will be described with reference to the drawings.

First, as shown in FIG. 7A, the magnetoresistive elements 11 and 14 detect the same change in the magnetic field and change the resistance at the same value. Also, the voltage across the magnetoresistive element 11 changes slightly, and the voltage at the other end of the magnetoresistive element 14 has the same phase as the voltage of the magnetoresistive element 11 and is higher than the voltage. .

The magnetoresistive element 12 detects a change in the magnetic field that is different from the magnetic field change of the magnetoresistive elements 11 and 14, and as shown in FIG. Changes in a reverse phase relationship with the change in the resistance value.

Therefore, the voltage at the other end of the magnetoresistive element 12 has a phase opposite to the voltage at the other end of the magnetoresistive element 14.

Further, since the first resistor 20a and the second resistor 20b have the same resistance value, the midpoint voltage V3
Is half the sum of the voltage V1 and the voltage V2. The comparator 19 compares the voltage V1 at the other end of the magnetoresistive element 12 with the midpoint voltage V3.

That is, the voltage V1 at the other end of the magnetoresistive element 12 has a phase opposite to that of the midpoint voltage V3, and
Since the voltage at the other end of the magnetoresistive element 14 is a relatively large voltage, even if the magnetoresistive elements 11, 12, and 14 vary, as shown in FIG. The voltage V1 at the other end of the magnetoresistive element 12 crosses.

As a result, as shown in FIG. 7C, the comparator 19 outputs the output voltage VO during a period when the voltage V1 is higher than the voltage V3.

As described above, the magnetoresistive elements 11, 1
Even if the resistance value or resistivity of 2, 14 varies,
Since the voltage V1 and the voltage V3 tend to overlap, a stable output signal can be obtained.

(Embodiment 3) FIG. 8 shows a configuration diagram of an integrated magnetoresistive element circuit according to Embodiment 3 of the present invention. The integrated magnetoresistive element circuit of the third embodiment shown in FIG. 8 is different from the circuit of the second embodiment in that a third resistor 20c,
It is characterized in that variable resistors 20d and 25 and a differential amplifier circuit 27 are provided.

One end of the third resistor 20c is connected to the other end of the magnetoresistive element 12, and the other end of the third resistor 20c is connected to the inverting input terminal of the differential amplifier 27. Between the inverting input terminal of the differential amplifier circuit 27 and the output terminal of the differential amplifier circuit 27, a variable resistor 20d that varies the feedback voltage according to the resistance ratio with the third resistor 20c is connected.

The output terminal of the differential amplifier circuit 27 is connected to the non-inverting input terminal of the comparator 19. The variable resistor 25 is connected to the other end of the DC power supply 10 and the transistors 15 and 1.
6 and 17 are connected between the emitters 6 and 17 to vary the voltage V3 at the midpoint terminal.

The differential amplifier circuit 27 includes the magnetoresistive element 1
2 and a voltage difference between the voltage V3 at the midpoint terminal changed by the variable resistor 25 and the amplified output is output to the inverting input terminal of the comparator 19.

Since other structures are the same as those of the second embodiment, the same parts are denoted by the same reference numerals and the details are omitted.

Next, the operation of the integrated magnetoresistive element circuit having the above-described configuration according to the third embodiment will be described.

First, a case where the resistance value of the variable resistor 25 is not adjusted will be described. Magnetoresistance effect elements 11 and 14
The resistance changes at the same value as shown in FIG.
The voltage V2 at the other end of the magnetoresistive element 14 has a relatively small amplitude as shown in FIG.
1 in phase.

The resistance value of the magnetoresistive element 12 changes in a relationship opposite to the change in the resistance values of the magnetoresistive elements 11 and 14, and its voltage V 1 is equal to the voltage at the other end of the magnetoresistive element 14. Is a voltage of the opposite phase, and as shown in FIG.
Relatively large amplitude.

Further, since the resistance values of the first resistor 20a and the second resistor 20b are the same, the midpoint voltage V3
Is half the sum of the voltage V1 and the voltage V2, and the voltage V3 has a relatively small amplitude as shown in FIG.
It is applied to the non-inverting input terminal of the differential amplifier circuit 27.

Further, the voltage V1 is applied to the inverting input terminal of the differential amplifier circuit 27 via the third resistor 20c. The differential amplifier circuit 27 amplifies the difference voltage between the voltage V1 and the voltage V3, and outputs an amplified voltage V4 having a large amplitude to the comparator 19, as shown in FIG.

The comparator 19 determines that the amplified voltage V4 crosses the voltage V3 at the time when the amplified voltage V4 crosses the voltage V3.
An output signal is output during a period greater than

However, since the variable resistor 25 is not adjusted, waveform distortion occurs in the amplified voltage V4, and stable signal processing cannot be performed.

Next, each waveform when the variable resistor 25 is adjusted is shown in FIG. The change in the resistance of the magnetoresistive elements 11, 12, and 14 shown in FIG.
Is the same as that shown in FIG.

First, the variable resistor 25 is adjusted so that the voltage V1
When the midpoint voltage V3 between the voltage V2 and the voltage V2 is set to about Vdd / 2, which is half the supply voltage Vdd of the DC power supply 10, the amplified voltage V4
As shown in FIG. 10 (c), the amplitude becomes substantially the same in the vertical direction with respect to the voltage V3.

That is, since the waveform distortion of the amplified voltage V4 does not occur, the amplification degree of the differential amplifier circuit 27 can be further increased, and more stable signal processing can be performed.

[0074]

According to the present invention, the resistance values of the first and second magnetoresistive elements change at the same value due to the same magnetic field change. Further, the resistance value of the third magnetoresistive element changes in a phase opposite to that of the first and second magnetoresistive elements due to different magnetic fields.

When the current mirror circuit causes the same current to flow through the first to third magnetoresistive elements, the voltage between both ends of the first magnetoresistive element changes slightly, and the second magnetoresistive element changes. Is in phase with the voltage of the first magnetoresistive element and is higher than that voltage.

The voltage at the other end of the third magneto-resistance effect element has a phase opposite to that of the voltage at the other end of the second magneto-resistance effect element. Then, the comparison circuit compares the voltage at the other end of the third magnetoresistive element with the voltage at the other end of the second magnetoresistive element.

That is, the voltage at the other end of the third magnetoresistive element has a phase opposite to that of the voltage at the other end of the second magnetoresistive element, and the voltage at the other end of the second magnetoresistive element is Since the voltage at the end is a relatively large voltage, the voltage at the other end of the third magnetoresistive element crosses the voltage at the other end of the second magnetoresistive element even if the magnetoresistive element varies. The comparison circuit outputs an output signal.

Accordingly, a stable output signal can be obtained even when the resistance or resistivity of the magnetoresistive element varies.

Since the first transistor has a collector and a base connected to the first current input terminal, the first transistor
The voltage at the other end of the magnetoresistive element is a voltage having a small amplitude, and since only the base of the second transistor is connected to the second current input terminal, the voltage at the other end of the second magnetoresistive element is Is a voltage having a relatively large amplitude.
The voltage at the other end of the magnetoresistive element and the voltage at the other end of the third magnetoresistive element are output to a comparison circuit.

The voltage at the other end of the third magnetoresistive element is input to one terminal of the comparison circuit, and the voltage at the other end of the second magnetoresistive element is compared with the voltage at the other end of the third magnetoresistive element. The voltage at the end is divided by a first resistor and a second resistor, the divided voltage is input to the other terminal of the comparison circuit, and the comparison circuit compares the voltages to obtain an output signal. You can also.

Further, a variable resistor varies the voltage at the midpoint terminal, and the differential amplifier circuit varies the voltage at the other end of the third magnetoresistive element and the midpoint terminal varied by the variable resistor. Since the voltage difference from the voltage is amplified and the amplified output is output to one terminal of the comparison circuit, the amplified output can perform stable signal processing without generating waveform distortion.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an integrated magnetoresistive element circuit according to a first embodiment of the present invention.

FIG. 2 is a timing chart when a resistance value of each magnetoresistive element changes in the first embodiment.

FIG. 3 is a diagram showing an example of an arrangement of a magnetoresistive element according to the first embodiment;

FIG. 4 is a diagram illustrating a configuration example of three magnetoresistive elements according to the first embodiment;

FIG. 5 is a diagram showing patterns of two identical magnetoresistive elements according to the second embodiment.

FIG. 6 is a configuration diagram of an integrated magnetoresistive element circuit according to a second embodiment of the present invention.

FIG. 7 is a timing chart when a resistance value of each magnetoresistive element changes in the second embodiment.

FIG. 8 is a configuration diagram of an integrated magnetoresistive element circuit according to a third embodiment of the present invention.

FIG. 9 is a timing chart when the variable resistor is not adjusted in the third embodiment.

FIG. 10 is a timing chart when a variable resistor is adjusted in the third embodiment.

FIG. 11 is a diagram showing an example of a conventional integrated magnetoresistive element circuit.

FIG. 12 is a timing chart showing input / output voltages of a comparator in a conventional integrated magnetoresistive element circuit.

FIG. 13 is a timing chart showing input / output voltages of a comparator when a magnetoresistive element in a conventional integrated magnetoresistive element circuit varies.

[Explanation of symbols]

 Reference Signs List 8 Insulating substrate 10 DC power supply 11, 12, 13, 14 Magnetoresistive element 15, 16, 17 Transistor 18 Capacitor 19 Comparator 20a First resistor 20b Second resistor 20c Third resistor 21 Gear 23 Bias magnet 20d, 25 Variable resistor 110 MR pattern

Claims (4)

[Claims] 1. A first and second magnetoresistive element, one end of which is connected to one end of a DC power supply, each of which detects the same magnetic field change and changes the resistance value by the magnetic field change; And a third magnetoresistive element whose resistance changes in a phase opposite to that of the first and second magnetoresistive elements due to the magnetic field change. The other ends of the first and second magnetoresistive elements are connected to a current input terminal, the other ends of the third magnetoresistive elements are connected to a current output terminal, and a common terminal is connected to the other end of the DC power supply. A current mirror circuit for causing a current equal to the first to third magnetoresistive elements to flow and for slightly changing the voltage across the first magnetoresistive element with respect to a change in resistance; and a second magnetoresistive element. Voltage at the other end of the device and the third magnetoresistive element A comparison circuit for comparing the voltage at the other end of the circuit with the other. 2. A current mirror circuit comprising: a first transistor having a collector and a base connected to a first current input terminal; a second transistor having a base connected to a second current input terminal; A third transistor having a collector connected to the output terminal, a base connected to the base of the first transistor, and an emitter connected to the emitters of the first and second transistors. 2. The integrated magnetoresistive element circuit according to claim 1. 3. The other end of the third magnetoresistive element is connected to one terminal of the comparison circuit, and the other end of the second magnetoresistive element is connected to the other terminal of the third magnetoresistive element. A first resistor and a second resistor connected in series between the first and second terminals, and a midpoint terminal connecting the first resistor and the second resistor is connected to the other terminal of the comparison circuit. 3. The integrated magnetoresistive element circuit according to claim 1, wherein the integrated magnetoresistive element circuit is connected. 4. A variable resistor for varying a voltage at the midpoint terminal; and a third resistor provided between the other end of the third magnetoresistive element and one terminal of the comparison circuit. A differential amplifier circuit that amplifies the voltage difference between the voltage at the other end of the resistance element and the voltage at the midpoint terminal changed by the variable resistor, and outputs the amplified output to one terminal of the comparison circuit; The integrated magnetoresistive element circuit according to claim 3, further comprising: