Magnetometer with angled set/reset coil

• US 9,372,242 B2
• Filed: 05/09/2013
• Issued: 06/21/2016
• 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
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): MCANDREW, CHRISTOPHER P
• Application Number:
  US13/890,723
• Publication Number:
  US 20130300408A1
• Time in Patent Office: 1,139 Days
• Field of Search: 324/252
• US Class Current: 1/1
• 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 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;

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

alternatingly in sense with respect to adjacent sensing strips, where 0°

<

α

<

90°

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

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 angle α

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

<

α

<

90°

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

wherein a third coil leg is oriented to cross a respective third portion of each sensing strip in the first plurality of sensing strips;

wherein the first and second portions of each first sensing strip are first and second end sections of each first sensing strip, respectively, and the third portion is a middle section of each first sensing strip;

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,

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

alternatingly in sense with respect to adjacent sensing strips where 0″

<

α

<

90°

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

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

alternatingly in sense with respect to adjacent sensing strips where 0″

<

α

<

90°

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

wherein a sixth coil is oriented to cross a respective third portion of each sensing strip in the second plurality of sensing strips.

2. The magnetometer of claim 1, wherein:

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

3. The magnetometer of claim 1, 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

alternatingly with respect to adjacent sensing strips, where 0°

<

α

<

90°

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

4. The magnetometer of claim 1, 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.

5. The magnetometer of claim 3, 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.

6. The magnetometer of claim 1, wherein the first and second pluralities of sensing strips are coupled to one another as a Wheatstone Bridge circuit.

7. 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;

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

alternatingly in sense with respect to adjacent sensing strips, where 0°

<

α

<

90°

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

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

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

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

<

α

<

90°

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

wherein a third coil leg is oriented to cross a respective third portion of each sensing strip in the first plurality of sensing strips;

wherein the first and second portions of each first sensing strip are first and second end sections of each first sensing strip, respectively, and the third portion is a middle section of each first sensing strip.