Current sensor

• US 20070090825A1
• Filed: 09/26/2006
• Published: 04/26/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Shoji, Shigeru
• Granted Patent: US 7,902,811 B2
• Time in Patent Office: Days
• US Class Current: 324/117.00R
• CPC Class Codes: G01R 15/205 using magneto-resistance devices, e.g. field plates
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

The present invention provides a current sensor of smaller and simpler configuration, capable of measuring a current to be detected with high precision and stability. A current sensor has a V-shaped conductor line and a pair of magnetoresistive elements disposed along with the conductor line so that a resistance value of one of the magnetoresistive elements changes in a direction opposite to that of resistance-value-change of the other magnetoresistive element according to current magnetic fields produced by a current to be detected flowing through the conductor line.

Claims

1. A current sensor comprising:

a V-shaped conductor line; and

a pair of magnetoresistive elements disposed along with the conductor line so that a resistance value of one of the magnetoresistive elements changes in a direction opposite to that of resistance-value-change of the other magnetoresistive element according to current magnetic fields produced by a current to be detected flowing through the conductor line.

2. The current sensor according to claim 1, wherein one of the magnetoresistive elements is arranged on one of a pair of arms forming the V-shape in the conductor line, and the other magnetoresistive element is arranged on the other arm.

4. The current sensor according to claim 1, wherein the magnetoresistive element includes:

a pinned layer having a magnetization direction pinned to a direction;

a free layer whose magnetization direction changes according to an external magnetic field, while the magnetization direction under no external magnetic field is parallel or antiparallel to the direction in which the conductor line is extending; and

an intermediate layer inserted between the pinned layer and the free layer.

6. The current sensor according to claim 4, wherein the magnetization direction of the pinned layer is orthogonal to the magnetization direction of the free layer when no external magnetic field is applied.

7. The current sensor according to claim 6, further comprising a pair of bias applying means each applying a bias magnetic field to each of the magnetoresistive elements in a direction same as that of the magnetization direction of the free layer under no external magnetic field.

8. The current sensor according to claim 7, wherein the bias applying means is a magnetic sheet attached on one side of the magnetoresistive element.

9. The current sensor according to claim 4, wherein the magnetization direction of the pinned layer is parallel to the magnetization direction of the free layer when no external magnetic field is applied.

10. The current sensor according to claim 9, further comprising a pair of bias applying means each applying a bias magnetic field to each of the magnetoresistive elements, respectively, the bias magnetic field having a parallel component parallel to the magnetization direction of the pinned layer and an orthogonal component orthogonal to the parallel component.

11. The current sensor according to claim 10, wherein the bias applying means is a magnetic sheet attached on one side of the magnetoresistive elements.

12. The current sensor according to claim 1, further comprising:

a pair of constant current sources each supplying a constant current of a common magnitude to each of the magnetoresistive elements; and

a difference detector detecting a difference in the voltage drops resulting from the constant current in each of the magnetoresistive elements.

3. A current sensor comprising:

a straight-line conductor line; and

a pair of magnetoresistive elements disposed along with the conductor line so that a resistance value of one of the magnetoresistive elements changes in a direction opposite to that of resistance-value-change of the other magnetoresistive element according to a current magnetic field produced by a current to be detected flowing through the conductor line.

5. The current sensor according to claim 3, wherein the magnetoresistive element includes:

a pinned layer having a magnetization direction pinned to a direction;

a free layer whose magnetization direction changes according to an external magnetic field, while the magnetization direction under no external magnetic field is parallel or antiparallel to the direction in which the conductor line is extending; and

an intermediate layer inserted between the pinned layer and the free layer.

13. The current sensor according to claim 3, further comprising:

a pair of constant current sources each supplying a constant current of a common magnitude to each of the magnetoresistive elements; and

a difference detector detecting a difference in the voltage drops resulting from the constant current in each of the magnetoresistive elements.

14. A current sensor comprising:

a V-shaped conductor line generating current magnetic fields according to a supplied current to be detected; and

first through fourth magnetoresistive elements disposed along with the conductor line so that resistance value of each of the magnetoresistive elements changes according to the current magnetic field,

wherein one end of the first magnetoresistive element and one end of the second magnetoresistive element are connected each other in a first junction point, one end of the third magnetoresistive element and one end of the fourth magnetoresistive element are connected each other in a second junction point, the other end of the first magnetoresistive element and the other end of the fourth magnetoresistive element are connected each other in a third junction point, and the other end of the second magnetoresistive element and the other end of the third magnetoresistive element are connected each other in a fourth junction point, thereby configuring a bridge circuit.

15. The current sensor according to claim 14, wherein the first and the third magnetoresistive elements are arranged on one of a pair of arms forming the V-shape in the conductor line, while the second and the fourth magnetoresistive elements are arranged on the other arm forming so that the arrangement of the first and the third magnetoresistive elements and the arrangement of the second and the fourth magnetoresistive elements are symmetric to each other.

16. A current sensor comprising:

a straight-line conductor line generating a current magnetic field according to a supplied current to be detected; and

first through fourth magnetoresistive elements disposed along with the conductor line so that resistance value of each of the magnetoresistive elements changes according to the current magnetic field,

wherein one end of the first magnetoresistive element and one end of the second magnetoresistive element are connected each other in a first junction point, one end of the third magnetoresistive element and one end of the fourth magnetoresistive element are connected each other in a second junction point, the other end of the first magnetoresistive element and the other end of the fourth magnetoresistive element are connected each other in a third junction point, and the other end of the second magnetoresistive element and the other end of the third magnetoresistive element are connected each other in a fourth junction point, thereby configuring a bridge circuit.

17. The current sensor according to claim 16, wherein the first and the third magnetoresistive elements are arranged on one of a pair of arms forming the V-shape in the conductor line, while the second and the fourth magnetoresistive elements are arranged on the other arm forming so that the arrangement of the first and the third magnetoresistive elements and the arrangement of the second and the fourth magnetoresistive elements are symmetric to each other.