MAGNETOMETER WITH ANGLED SET/RESET COIL

• US 20130300408A1
• Filed: 05/09/2013
• Published: 11/14/2013
• Est. Priority Date: 05/11/2012
• Status: Active Grant

• Current Assignee: Memsic Semiconductor (Wuxi) Co., Ltd. (MZ Investment Holdings Ltd.)
• Original Assignee: Memsic Incorporated (MZ Investment Holdings Ltd.)
• Inventors: Qiu, Jiaoming, Cai, Yongyao
• Granted Patent: US 9,372,242 B2
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: G01R 33/09 Magnetoresistive devices
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/096 anisotropic magnetoresistance sensors
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors

Abstract

A magnetometer with a set/reset coil having portions that cross portions of sensing strips at an angle in order to create a magnetic field in the sensing strip that is at an angle with respect to the easy axis of magnetization of the sensing strip. Each sensing strip may have a portion having a magnetic field created therein that is different from a magnetic field created in another portion of the same sensing strip. As a result, a lower set/reset coil current is needed to initialize the magnetometer.

Claims

1. A magnetometer, comprising:

a plurality of sensing strips disposed on a planar substrate, each sensing strip having a long axis; and

a planar set/reset coil disposed on the planar substrate parallel and adjacent to the plurality of sensing strips,

wherein a first coil portion of the set/reset coil is oriented with respect to a first portion of a first sensing strip at a first angle +α

1, where 0°

<

α

1<

90°

, with respect to a virtual line perpendicular to the long axis of the first sensing strip.

2. The magnetometer of claim 1, wherein the set/reset coil comprises a second coil portion oriented, with respect to a second portion of the first sensing strip at a second angle −

α

2, where |−

α

1|=|+α

2|, with respect to the virtual line perpendicular to the long axis of the first sensing strip.

3. The magnetometer of claim 1, wherein the set/reset coil comprises a second coil portion oriented, with respect to a second portion of the first sensing strip at the first angle +α

1, with respect to the virtual line perpendicular to the long axis of the first sensing strip.

4. The magnetometer of claim 2, wherein the set/reset coil comprises a third coil portion oriented perpendicularly to a third portion of the first sensing strip.

5. The magnetometer of claim 4, wherein the first and second portions of the first sensing strip are first and second end sections of the first sensing strip, respectively, and the third portion is a middle section of the first sensing strip.

6. The magnetometer of claim 4, wherein the first and second coil portions are of the same width.

7. The magnetometer of claim 6, wherein the third coil portion is substantially wider than the width of the first and second coil portions.

8. The magnetometer of claim 3, wherein the set/reset coil comprises a third coil portion oriented perpendicularly with respect to a third portion of the first sensing strip.

9. The magnetometer of claim 3, wherein the set/reset coil comprises a third coil portion oriented, with respect to a third portion of the first sensing strip at the first angle +α

1, with respect to the virtual line perpendicular to the long axis of the first sensing strip.

10. The magnetometer of claim 1, wherein the set/reset coil comprises a second coil portion oriented, with respect to a first portion of a second sensing strip, at a second angle −

α

2, where |+α

1|=|−

α

2|, with respect to a virtual line perpendicular to a long axis of the second sensing strip,

wherein the first and second sensing strips are arranged adjacent to one another with respective long axes substantially parallel to one another.

11. The magnetometer of claim 1, wherein the plurality of sensing strips are coupled to one another as a Wheatstone Bridge circuit.

12. A magnetometer, comprising:

a first plurality of sensing strips disposed on a planar substrate, each sensing strip having a long axis and first, second and third portions, arranged adjacent to one another with respective long axes substantially parallel to one another; and

a planar set/reset coil, disposed on the planar substrate parallel and adjacent to the first plurality of sensing strips, having a plurality of undulating coil legs,

wherein a first coil leg is oriented to cross a respective first portion of each sensing strip in the first plurality of sensing strips at angles +α

1, −

α

2, alternatingly with respect to adjacent sensing strips, where 0°

<

(α

1=α

2)<

90°

with respect to a virtual line perpendicular to the long axis of each sensing strip.

13. The magnetometer of claim 12, further comprising:

a second plurality of sensing strips disposed on the planar substrate, each sensing strip having a long axis and first, second and third portions, arranged adjacent to one another with respective long axes substantially parallel to one another,

wherein the first and second pluralities of sensing strips are arranged in equal columns.

14. The magnetometer of claim 12, wherein:

a second coil leg is oriented to cross a respective second portion of each sensing strip in the first plurality of sensing strips at angles +α

1, −

α

2, alternatingly with respect to adjacent sensing strips, where 0°

<

(α

1=α

2)<

90°

with respect to a virtual line perpendicular to the long axis of each sensing strip.

15. The magnetometer of claim 14, wherein:

a third coil leg is oriented to cross a respective third portion of each sensing strip in the first plurality of sensing strips at angles +α

1, −

α

2, alternatingly with respect to adjacent sensing strips, where 0°

<

(α

1=α

2)<

90°

with respect to a virtual line perpendicular to the long axis of each sensing strip.

16. The magnetometer of claim 15, wherein:

a width of the third coil leg is larger than a respective width of each of the first and second coil legs.

17. The magnetometer of claim 12, wherein:

a second coil leg is oriented to cross a respective second portion of each sensing strip in the first plurality of sensing strips at angles −

α

1, +α

2, alternatingly with respect to adjacent sensing strips, where 0°

<

(α

1=α

2)<

90°

with respect to a virtual line perpendicular to the long axis of each sensing strip.

18. The magnetometer of claim 14, wherein:

a third coil leg is oriented to cross a respective third portion of each sensing strip in the first plurality of sensing strips substantially perpendicular to the long axis of each sensing strip.

19. The magnetometer of claim 17, wherein:

a third coil leg is oriented to cross a respective third portion of each sensing strip in the first plurality of sensing strips substantially perpendicular to the long axis of each sensing strip.

20. The magnetometer of claim 13, wherein the first and second pluralities of sensing strips are coupled to one another as a Wheatstone Bridge circuit.