METHODS AND APPARATUS FOR MAGNETIC SENSOR HAVING INTEGRATED COIL

• US 20130300406A1
• Filed: 05/10/2012
• Published: 11/14/2013
• Est. Priority Date: 05/10/2012
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Pepka, Gary T., Taylor, William P.
• Granted Patent: US 9,817,078 B2
• Time in Patent Office: Days
• US Class Current: 324/244
• CPC Class Codes: G01R 33/0017 Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields
• CPC Class Codes: G01R 33/0035 Calibration of single magnetic sensors, e.g. integrated calibration
• CPC Class Codes: G01R 33/09 Magnetoresistive devices

Abstract

Methods and apparatus for a magnetic field sensor including a die, a coil proximate the die to generate a magnetic field, and a magnetic field sensing element having to detect changes in the magnetic field generated by the coil in response to a ferromagnetic target.

Claims

1. A magnetic field sensor, comprising:

a die;

a coil proximate the die to generate a magnetic field; and

a magnetic field sensing element on said die to detect changes in the magnetic field generated by the coil as a result of the presence of a ferromagnetic target.

2. The sensor according to claim 1, wherein the coil is integrated with the die.

3. The sensor according to claim 1, wherein the coil is substantially flat.

4. The sensor according to claim 1, wherein the coil comprises a solenoid.

5. The sensor according to claim 1, wherein the only a portion of the magnetic field sensing element overlaps with the coil.

6. The sensor according to claim 1, wherein the magnetic field sensing element is positioned at least in part between the coil and the die.

7. The sensor according to claim 1, wherein the coil is positioned at least in part between the magnetic field sensing element and the die.

8. The sensor according to claim 1, wherein the magnetic field sensing element comprises a Giant magnetoresistance element.

9. The sensor according to claim 1, wherein about half of an area of the magnetic field sensing element overlaps with the coil.

10. The sensor according to claim 1, wherein about half of a length of the magnetic field sensing element overlaps with the coil.

11. The sensor according to claim 1, wherein sensor includes a further magnetic field sensing element.

12. The sensor according to claim 11, wherein the magnetic field sensing element comprises a Hall element and the further magnetic field sensing element comprises a giant magnetoresistance element.

13. The sensor according to claim 1, wherein the die includes circuitry to process information from the magnetic field sensor.

14. The sensor according to claim 1, further including a constant current source coupled to the coil.

15. The sensor according to claim 1, further including a pulse current source coupled to the coil.

16. The sensor according to claim 1, wherein the magnetic field sensing element has at least a portion that overlaps the coil.

17. A magnetic field sensor, comprising:

a die;

a first means proximate the die for generating a magnetic field; and

a second means for detecting changes in the magnetic field generated by the first means as a result of the presence of a ferromagnetic target.

18. The sensor according to claim 17, wherein the first means is integrated with the die.

19. The sensor according to claim 17, wherein the first means comprises a magnetoresistance element.

20. The sensor according to claim 17, wherein the first means further comprises a Hall element.

21. A method, comprising:

providing a die;

providing a coil proximate the die to generate a magnetic field; and

providing a magnetic field sensing element to detect changes in the magnetic field generated by the coil as a result of the presence of a ferromagnetic target.

22. The method according to claim 21, wherein the coil is integrated on the die.

23. The method according to claim 21, wherein the magnetic field sensing element is positioned at least in part between the coil and the die.

24. The method according to claim 21, wherein the coil is positioned at least in part between the magnetic field sensing element and the die.

25. The method according to claim 21, wherein the magnetic field sensing element comprises a giant magnetoresistance element and a Hall element.

26. The method according to claim 21, wherein the magnetic field sensing element has at least a portion that overlaps the coil.