Magnetic-Field Sensor and Method of Calibrating a Magnetic-Field Sensor

• US 20110187350A1
• Filed: 04/13/2011
• Published: 08/04/2011
• Est. Priority Date: 06/28/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hammerschmidt, Dirk, Ausserlechner, Udo
• Granted Patent: US 8,766,623 B2
• Time in Patent Office: Days
• US Class Current: 324/202
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: G01R 33/0035 Calibration of single magnetic sensors, e.g. integrated calibration
• CPC Class Codes: G01R 33/09 Magnetoresistive devices
• CPC Class Codes: G01R 33/095 extraordinary magnetoresistance sensors

Abstract

An embodiment of a magnetic-field sensor has a plurality of sensor elements connected to form measurement arrangements, each measurement arrangement having a measurement tap, and a control circuit formed to perform an embodiment of a method of calibrating the magnetic-field sensor.

Claims

1. A method of calibrating a magnetic-field sensor comprising a plurality of sensor elements connected to form measurement arrangements each measurement arrangement comprising a measurement tap, comprising:

supplying the measurement arrangement with an excitation signal to generate a tappable measuring signal at each measurement tap of the measurement arrangements;

detecting the measuring signals;

evaluating the detected measuring signals by comparing the detected measuring signals with a comparison value; and

determining the measurement arrangement with the smallest difference, in terms of magnitude, from the comparison value.

2. The method according to claim 1, further comprising storing information regarding the determined measurement arrangement in a memory of the magnetic-field sensor.

3. The method according to claim 2, wherein storing comprises permanently writing information regarding the determined measurement arrangement into the memory.

4. The method according to claim 1, wherein detecting the measuring signals comprises sequentially detecting the measuring signals of the individual measurement arrangements.

5. The method according to claim 1, wherein detecting the measuring signals comprises sequentially coupling the measurement taps of each measurement arrangement to a control circuit of the magnetic-field sensor and detecting a measuring signal of the measurement arrangement coupled to the control circuit.

6. The method according to claim 1, wherein detecting the measuring signals comprises detecting the measuring signals with reference to a reference signal of a reference tap of a reference arrangement, wherein the reference arrangement comprises a resistive element.

7. The method according to claim 6, wherein evaluating the detected measuring signals by comparing the detected measuring signals with a comparison value comprises comparing with a value of zero.

8. The method according to claim 1, wherein evaluating the detected measuring signals by comparing the detected measuring signals with a comparison value comprises comparing with a value of 50% of a voltage value of the excitation signal if a measurement arrangement comprises a half-bridge circuit with at least one sensor element, or comparing with a value of zero if a measurement arrangement comprises a full-bridge circuit with at least one sensor element.

9. The method according to claim 1, further comprising positioning or moving an indicator object.

10. The method according to claim 9, wherein positioning or moving the indicator object comprises orienting the indicator object such that a magnetic field at a center of a chip of the magnetic-field sensor corresponds to a central magnetic field at the center, averaged over a period of a movement of the indicator object, wherein the indicator object leads to a periodic change of the magnetic field when the indicator object is moved.

11. The method according to claim 9, wherein positioning or moving of the indicator object comprises moving the indicator object so that the magnetic-field sensor is exposed to a periodically changing magnetic field with a duration of at least two periods.

12. A magnetic-field sensor, comprising:

a plurality of sensor elements connected to form measurement arrangements, each measurement arrangement comprising a measurement tap, and

a control circuit coupled to the measurement taps of the measurement arrangements, wherein the control circuit is formed to supply the measurement arrangements with an excitation signal to generate a tappable measuring signal at each measurement tap of the measurement arrangements, further formed to detect the measuring signals, further formed to evaluate the detected measuring signals by comparing the detected measuring signals with a comparison value, and formed to determine the measurement arrangement with the smallest difference, in terms of magnitude, from the comparison value.

13. The magnetic-field sensor according to claim 12, wherein the measurement arrangements each comprise at least one sensor element.

14. The magnetic-field sensor according to claim 12, wherein a common sensor element belongs to two different measurement arrangements.

15. The magnetic-field sensor according to claim 12, wherein the measurement arrangements comprise a series connection of two sensor elements with a measurement tap connected between the two sensor elements.

16. The magnetic-field sensor according to claim 12, wherein the measurement arrangements comprise a parallel connection of two series connections, wherein at least one of the two series connections comprises at least one sensor element.

17. The magnetic-field sensor according to claim 12, wherein the sensor elements are arranged on a chip of the magnetic-field sensor in a manner shifted laterally with respect to each other.

18. The magnetic-field sensor according to claim 12, wherein the sensor elements are magnetoresistive sensor elements.

19. The magnetic-field sensor according to claim 12, wherein the control circuit comprises a multiplexer coupled to the measurement taps of the measurement arrangements, and wherein the multiplexer is formed to couple one of the measurement taps to an output of the multiplexer in response to a control signal.

20. The magnetic-field sensor according to claim 19, wherein an analog/digital converter is coupled to the output of the multiplexer, so that the analog/digital converter can be coupled to a center tap of the measurement arrangements each.

21. The magnetic-field sensor according to claim 12, wherein the control circuit comprises an analog/digital converter which can be coupled to at least one center tap of a measurement arrangement.

22. The magnetic-field sensor according to claim 12, wherein the control circuit further comprises a pre-processing circuit formed to filter detected measuring signals.

23. The magnetic-field sensor according to claim 12, wherein the control circuit further comprises a processor circuit formed to provide an output signal, based on at least one of the detected measuring signals.

24. The magnetic-field sensor according to claim 12, wherein the control circuit further comprises a supply circuit coupled to the measurement arrangements via a first terminal and a second terminal of the measurement arrangements and formed to impress an excitation signal on the measurement arrangements.

25. The magnetic-field sensor according to claim 12, wherein the control circuit further comprises a reference measurement arrangement with a reference tap, and wherein the reference measurement arrangement comprises a resistive element.

26. The magnetic-field sensor according to claim 12, wherein the control circuit further comprises a memory allowing for non-volatile storage or one-time storage of information.

27. A program with a program code for performing, when the program is executed on a processor, a method of calibrating a magnetic-field sensor comprising a plurality of sensor elements connected to form measurement arrangements each measurement arrangement comprising a measurement tap, the method comprising supplying the measurement arrangement with an excitation signal to generate a tappable measuring signal at each measurement tap of the measurement arrangements detecting the measuring signals, evaluating the detected measuring signals by comparing the detected measuring signals with a comparison value, and determining the measurement arrangement with the smallest difference, in terms of magnitude, from the comparison value.