SINGLE-CHIP PUSH-PULL BRIDGE-TYPE MAGNETIC FIELD SENSOR

• US 20140035570A1
• Filed: 04/01/2012
• Published: 02/06/2014
• Est. Priority Date: 04/06/2011
• Status: Active Grant

• Current Assignee: Multidimension Technology Co., Ltd
• Original Assignee: Multidimension Technology Co., Ltd
• Inventors: Jin, Insik, Lei, Xiaofeng, Deak, James Geza, Shen, Weifeng, Xue, Songsheng, Li, Wei
• Granted Patent: US 9,664,754 B2
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01R 33/0005 Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types G01R33/0206 takes precedence
• CPC Class Codes: G01R 33/0011 comprising means, e.g. flux concentrators, flux guides, for guiding or concentrating the magnetic flux, e.g. to the magnetic sensor
• CPC Class Codes: G01R 33/09 Magnetoresistive devices
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• CPC Class Codes: G06Q 10/00 Administration; Management
• CPC Class Codes: G06Q 2220/00 Business processing using cryptography
• CPC Class Codes: G07F 1/00 Coin inlet arrangements; Coins specially adapted to operate coin-freed mechanisms
• CPC Class Codes: H04L 9/50 using hash chains, e.g. blockchains or hash trees
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one galvanomagnetic or Hall-effect element covered by groups H10N50/00 - H10N52/00 MRAM devices H10B61/00

Abstract

The present invention discloses a design of a single-chip push-pull bridge sensor, composed of magnetoresistive elements, utilizing on-chip permanent magnets. The permanent magnets are oriented to preset magnetization directions of free layers of adjacent sensor bridge arms so that they point to different directions with respect the same sensing direction, enabling push-pull operation. The push-pull bridge sensor of the present invention is integrated on a single chip. Additionally, an on-chip coil is disclosed to reset or calibrate the magnetization directions of the free layers of the magnetoresistive elements.

Claims

1. A single-chip push-pull magnetoresistive sensor bridge, comprising

a sensor bridge comprised of multitude of magnetoresistive sensor arms, wherein each magnetoresistive sensor arm comprises at least one MTJ, AMR or GMR magnetoresistive elements, and each magnetoresistive elements is sensitive to a magnetic field along a sensing direction;

and

permanent magnet bars disposed on two sides of each magnetoresistive element to bias the direction of the magnetization of said magnetoresistive element.

2. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 1, wherein the length of each permanent magnet is larger than the gap between adjacent permanent magnets in order to make the magnetic field between the permanent magnets uniform.

3. A single-chip push-pull bridge magnetoresistive sensor as claimed in claim 1, wherein each of a pair of the permanent magnets disposed on two sides of the magnetoresistive element has an edge closest to the magnetoresistive element, wherein the permanent magnet edge is set to form an angle with respect to the sensing direction of the magnetoresistive element, and said angle is either a sharp angle or an obtuse angle.

4. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 1, wherein the pair of the permanent magnets on the sides of the magnetoresistive element generate a magnetic bias field along a biasing direction.

5. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 4, wherein the magnitude of the magnetic bias field is dependent on the thickness of the permanent magnets.

6. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 4, wherein each of the pair of the permanent magnets disposed on two sides of a magnetoresistive element has an edge closest to the magnetoresistive element, and the strength of the permanent magnet bias field can be adjusted by varying the orientation of the magnetization directions of the permanent magnets or the angle of the edge boundary with respect to the sensing direction.

7. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 1, wherein the bias field provided by the permanent magnets is uniform.

8. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 1, wherein the magnetoresistive elements are parallel to each other.

9. A single-chip push-pull magnetoresistive sensor bridge as claimed in claim 1, further comprising an electric coil in the vicinity of the magnetoresistive elements, wherein there is an insulation layer between the magnetoresistive elements and the electric coil.