# US 2008/0186635 A1 · Magnetic field detector, and current detection device, position detection device and rotation detection devices using the magnetic field detector

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- Number: US 2008/0186635 A1
- Document ID: US20080186635A1
- Status: Published application
- Kind: A1
- Application number: 12/098,291
- Filed: 2008-04-04
- Published: 2008-08-07
- Earliest claimed: 2004-02-19
- Assignees: Mitsubishi Electric Corporation
- Inventors: Takashi TAKENAGA; Hiroshi Kobayashi; Takeharu Kuroiwa; Sadeh Beysen; Taisuke Furukawa
- Web page: https://patentgrep.com/patent/US20080186635A1

## CPC

- G01R 33/09: Magnetoresistive devices
- B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
- G01R 15/205: {using magneto-resistance devices, e.g. field plates}
- G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

A magnetic field detector having a reference magnetoresistive element and a magnetic field detecting magnetoresistive element. The reference magnetoresistive element and the magnetic field detecting magnetoresistive element each has a stack structure including an antiferromagnetic layer, a fixed layer of a ferromagnetic material with the direction of magnetization fixed by the antiferromagnetic layer, a nonmagnetic layer, and a free layer of a ferromagnetic material with the direction of magnetization adapted to be changed by an external magnetic field. The reference magnetoresistive element is such that the direction of magnetization of the fixed layer and the direction of magnetization of the free layer in the nonmagnetic field are parallel or antiparallel to each other, and the magnetic field detecting magnetoresistive element is such that the direction of magnetization of the fixed layer and the direction of magnetization of the free layer in the nonmagnetic field are different from each other. Thus, it is possible to provide a magnetic field detector capable of singly calibrating the sensitivity and the resolution of the detector whenever required.

## Claims

### Claim 1

A magnetic field detector comprising a first magnetoresistive element and a second magnetoresistive element, the first magnetoresistive element and the second magnetoresistive element each having a stack structure including:
an antiferromagnetic layer;
a first layer of a ferromagnetic material with the direction of magnetization fixed by the antiferromagnetic layer;
a nonmagnetic layer; and
a second layer of a ferromagnetic material with the direction of magnetization adapted to be changed by an external magnetic field,
the second magnetoresistive element is such that the direction of magnetization of the first layer and the direction of magnetization of the second layer in a nonmagnetic field being different from each other.

### Claim 2 (depends on 1)

The magnetic field detector according to claim 1, wherein
the direction of magnetization of the second layer in the nonmagnetic field of the first magnetoresistive element and the direction of magnetization of the second layer in the nonmagnetic field of the second magnetoresistive element are nonparallel or nonantiparallel to each other.

### Claim 3 (depends on 2)

The magnetic field detector according to claim 2, wherein
the direction of magnetization of the second layer in the nonmagnetic field of the first magnetoresistive element and the direction of magnetization of the second layer in the nonmagnetic field of the second magnetoresistive element are orthogonal to each other.

### Claim 4 (depends on 1)

The magnetic field detector according to claim 1, wherein
the first magnetoresistive element and the second magnetoresistive element have the same saturation value of a resistance with respect to the external magnetic field.

### Claim 5 (depends on 1)

The magnetic field detector according to claim 1, wherein
the first magnetoresistive element and the second magnetoresistive element produce an output signal by applying an electric current perpendicularly to the stack structure of the layers.

### Claim 6 (depends on 5)

The magnetic field detector according to claim 5, wherein
the first magnetoresistive element and the second magnetoresistive element have the same area.

### Claim 7 (depends on 1)

The magnetic field detector according to claim 1, wherein
the first magnetoresistive element is magnetically shielded.

### Claim 8 (depends on 1)

The magnetic field detector according to claim 1, further comprising:
a resistance-voltage conversion circuit for converting the resistance of the first magnetoresistive element and the resistance of the second magnetoresistive element into voltages; and
an add-subtract amplifier circuit for amplifying the difference between the voltages converted from the resistance of the first magnetoresistive element and the resistance of the second magnetoresistive element by the resistance-voltage conversion circuit.

### Claim 9 (depends on 1)

A current detection device using the magnetic field detector as set forth in claim 1.

### Claim 10 (depends on 1)

A position detection device using the magnetic field detector as set forth in claim 1.

### Claim 11 (depends on 1)

A rotation detection device using the magnetic field detector as set forth in claim 1.