JPH062116U - Magnetoresistive element - Google Patents

Abstract

(57) [Summary] [Purpose] The midpoint potential obtained as the output voltage can be adjusted without distorting the output waveform. [Structure] A non-magnetic resistor T is connected in series to either one of a first magnetic sensitive stripe S1 and a second magnetic sensitive stripe S2 each made of a ferromagnetic thin film. Since the midpoint potential can be changed by connecting the nonmagnetic resistor T, the midpoint potential can be adjusted to a value other than 1/2 of the power supply voltage.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetoresistive element adapted to obtain an output voltage having a value other than 1/2 of the power supply voltage.

[0002]

[Prior art]

 A conventional magnetoresistive element having a structure as shown in FIG. 4 is known. Between the power supply terminal T1 and the ground terminal T2, the first magnetic sensitive stripes S1 and the second magnetic sensitive stripes S2 each made of a ferromagnetic thin film are arranged in parallel with each other and connected in series. The output voltage is obtained from the connection point of the first and second magnetic sensitive stripes S1 and S2 via the output terminal T3.

Here, assuming that the resistances of the first and second magnetic sensitive stripes S1 and S2 are R1 and R2, respectively, R1 = R2 is set, and the power supply voltage V is set between the power supply terminal T1 and the ground terminal T2. cc is connected. A region M surrounded by a broken line shows a magnetic field region. In the magnetoresistive element having such a configuration, the midpoint potential Vc is obtained as the output voltage from the output terminal T3, but normally this value is 1/2 of the power supply voltage Vcc.

The output voltage obtained from the output terminal T3 of the magnetoresistive element is input to an operational amplifier (not shown) or the like for waveform shaping or comparison with a reference voltage. However, in the output of the operational amplifier, it may be possible to make the output waveform most effective by setting the reference voltage on the circuit higher than 1/2 of the power supply voltage Vcc. However, as described above, when the midpoint potential Vc of the magnetoresistive element is set to 1/2 of the power supply voltage Vcc, the power supply noise is amplified due to the potential difference from the reference voltage, and the output of the operational amplifier is output. This causes a problem that large noise is generated.

Therefore, it has been attempted to change the midpoint potential Vc so that the midpoint potential Vc of the output voltage of the magnetoresistive element matches the operational amplifier. The first attempt is to displace the midpoint potential Vc by increasing the width of the first magnetosensitive stripe S1 and changing the resistance value R1 thereof in FIG. 4, for example. The second attempt is to displace the midpoint potential Vc by adding, for example, the second magnetic sensitive stripe S2 to increase the resistance value R2 in FIG. As another third attempt, a resistor is connected in series to one magnetic sensitive stripe to change the midpoint potential Vc.

[0006]

[Problems to be solved by the device]

 However, in the conventional magnetoresistive element, when it is attempted to displace the midpoint potential Vc as in the first or second attempt, when a changing magnetic field is applied to the first and second magnetic stripes S1 and S2, naturally, However, the amount of change in resistance of each magnetic stripe becomes different. As a result, there is a problem that the output waveform of the midpoint potential Vc is distorted. Also in the third attempt, there is a problem that the resistance value needs to be adjusted, and further, the drift of the midpoint potential due to the temperature change deteriorates the detection accuracy.

The present invention has been made in consideration of the above problems, and it is possible to adjust the midpoint potential obtained as the output voltage to a value other than 1/2 of the power supply voltage without distorting the output waveform. It is intended to provide a resistance element.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a first magnetic sensitive strip and a second magnetic sensitive stripe, each of which is made of a ferromagnetic thin film, connected in series, and a midpoint potential is obtained as an output voltage from this connection point. A magnetoresistive element, characterized in that a nonmagnetic resistor is connected in series to one of the first or second magnetically sensitive stripes to adjust the value of the midpoint potential which becomes the output voltage. is there.

[0009]

[Action]

 By connecting the non-magnetic resistor in series to either one of the first and second magneto-sensitive stripes, the midpoint potential can be adjusted by the amount of the non-magnetic resistor connected. In addition, since the non-magnetic resistor is used and the first and second magneto-sensitive strips have the same shape, the change in resistance due to magnetism is also kept equal, so that the output waveform is not distorted.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of a magnetoresistive element of the present invention, in which a first magnetic sensitive stripe S1 and a second magnetic sensitive stripe S1 each made of a ferromagnetic thin film are provided between a power supply terminal T1 and a ground terminal T2. The magnetic stripes S2 are arranged in parallel with each other and connected in series. Here, the resistances R1 and R2 of the first and second magnetic sensitive stripes S1 and S2 are set to R1 = R2. Further, for example, between the second stripe S2 and the ground terminal T2, a non-magnetic resistor T arranged in a direction orthogonal to the second stripe S2 is connected in series. A power supply voltage Vcc is connected between the power supply terminal T1 and the ground terminal T2. A region M surrounded by a broken line shows a magnetic field region.

FIG. 3 shows an equivalent circuit of the magnetoresistive element of this embodiment. R3 represents the resistance of the non-magnetic resistor T. Here, the midpoint potential Vc obtained from the output terminal T3 is expressed by the following equation. Vc = {(R2 + R3) / (R1 + R2 + R3)} × Vcc Here, if Vcc = 5V, R1 = R2 = R, and R3 = 0.5R are set, Vc = 3 (V) becomes can get. On the other hand, in the conventional example of FIG. 5, since Vc = {R2 / (R1 + R2)} × Vcc, Vc = 2.5 (V) is obtained.

That is, according to the present embodiment, by connecting the non-magnetic resistor T in series with the second magnetic sensitive stripe S2, the output voltage obtained from the output terminal T3 is the midpoint corresponding to the connection. The potential can be adjusted to a value other than 1/2 of the power supply voltage Vcc. In the case of the present embodiment, since the midpoint potential Vc = 3 (V) is obtained for the power supply voltage Vcc = 5 (V), it is possible to shift the power supply voltage Vcc by 0.5 (V). Become . In this case, the first and second magneto-sensitive stripes S1 and S2 are provided in the same shape so that the resistors R1 and R2 are equal, so that the resistance change due to the magnetic field region M is kept equal. As a result, the midpoint potential can be adjusted to a value other than 1/2 of the power supply voltage without distorting the output waveform obtained from the output terminal T3.

As the non-magnetic resistor T, it is desirable to use a material having a resistance temperature coefficient close to that of a ferromagnetic thin film used as a magneto-sensitive stripe as much as possible. Furthermore, by providing the nonmagnetic resistor T in the stripe shape as in the embodiment, the resistance can be easily adjusted at the time of design.

FIG. 2 shows a second embodiment of the present invention, in which a non-magnetic resistor T is arranged in parallel with a second magnetically sensitive strip S2, and a second magnetic field is applied via an interruption terminal T4. It shows an example in which the magnetic stripes S2 are connected in series. Also in this embodiment, only the arrangement direction of the non-magnetic resistor T is different, and an equivalent circuit similar to that of the first embodiment is obtained, so that similar effects can be obtained. That is, since the resistance of the non-magnetic resistor T does not change due to magnetism, the value of the midpoint potential obtained from the output terminal T3 is set to a value other than 1/2 of the power supply voltage, regardless of the arrangement direction. Acts to adjust to.

Similarly, although not shown in the respective embodiments, the object can be achieved by connecting the non-magnetic resistor T in series with the first magnetically sensitive strip S1.

[0016]

[Effect of device]

 As described above, according to the present invention, the nonmagnetic resistor is connected in series to either one of the first and second magnetic stripes, each of which is made of a ferromagnetic thin film. The midpoint potential obtained as a voltage can be adjusted without distorting the output waveform.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a magnetoresistive element of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the magnetoresistive element of the present invention.

FIG. 3 is an equivalent circuit of the magnetoresistive element according to each embodiment of the present invention.

FIG. 4 is a configuration diagram showing a conventional magnetoresistive element.

FIG. 5 is an equivalent circuit of a conventional magnetoresistive element.

[Explanation of symbols]

 S1 First magnetic sensitive stripe S2 Second magnetic sensitive stripe T1 Power supply terminal T2 Ground terminal T3 Output terminal T4 Relay terminal T Non-magnetic resistor M Magnetic field area

Claims (1)

[Scope of utility model registration request] 1. A magnetoresistive element in which a first magnetic sensitive stripe and a second magnetic sensitive stripe each made of a ferromagnetic thin film are connected in series, and a midpoint potential is obtained as an output voltage from this connection point, A magnetoresistive element comprising a nonmagnetic resistor connected in series to one of the first or second magnetosensitive stripes to adjust the value of the midpoint potential which is the output voltage.