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

• US 20090001965A1
• Filed: 06/27/2008
• Published: 01/01/2009
• 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 8,076,927 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 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, and wherein the magnetic-field sensor is exposed to a magnetic field periodically changing at least in portions, comprising:

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

detecting the measuring signals of at least two measurement arrangements over at least one period of the magnetic field;

evaluating the detected measuring signals by determining the respective maximum and minimum measuring values of the detected measuring signals; and

determining the measurement arrangement with the greatest difference of the respective maximum and minimum measuring values.

13. The method according to claim 12, further comprising moving an indicator object, wherein moving the indicator object leads to the magnetic field changing periodically at least in portions at the magnetic-field sensor.

14. The method according to claim 12, wherein detecting the measuring signals of at least two measurement arrangements over at least one period of the magnetic field comprises detecting a plurality of measuring signals of a first measurement arrangement of the two measurement arrangements over at least one period of the magnetic field, switching to a second measurement arrangement of the at least two measurement arrangements, and detecting a plurality of measuring signals of the second measurement arrangement over at least one period of the magnetic field.

15. The method according to claim 12, wherein detecting the measuring signals of at least two measurement arrangements over at least one period of the temporally changing magnetic field comprises multiple execution of switching to a first measurement arrangement of the at least two measurement arrangements;

detecting a measuring signal of the first measurement arrangement;

switching to a second measurement arrangement of the at least two measurement arrangements; and

detecting a measuring signal of the second measurement arrangement over at least one period of the magnetic field changing at least in portions.

16. The method according to claim 12, further comprising storing information regarding the determined measurement arrangement in a memory of the magnetic-field sensor.

17. The method according to claim 12, wherein detecting the measuring signals comprises detecting the measuring signals with respect to a reference signal of a reference tap of a reference arrangement, wherein the reference arrangement comprises a resistive element.

18. 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, wherein the magnetic-field sensor is exposed to a magnetic field periodically changing at least in portions, comprising:

determining a measurement arrangement as present measurement arrangement;

determining a further measurement arrangement as comparison measurement arrangement, which is not the present measurement arrangement;

supplying the present measurement arrangement and the comparison measurement arrangement with an excitation signal, to generate a tappable measuring signal at the measurement arrangement of the present measurement arrangement and the comparison measurement arrangement;

detecting measuring signals of the present measurement arrangement;

providing an output signal on the basis of the detected measuring signal of the present measurement arrangement;

evaluating the detected measuring signals of the present measurement arrangement by determining a minimum measuring value and a maximum measuring value of the present measurement arrangement;

detecting a first measuring value of the comparison measurement arrangement if a detected measuring signal of the present measurement arrangement corresponds to the maximum measuring value of the present measurement arrangement;

detecting a second measuring signal of the comparison measurement arrangement if a detected measuring signal of the present measurement arrangement corresponds to the minimum measuring value of the present measurement arrangement; and

determining the comparison measurement arrangement as the present measurement arrangement if a difference of the first measuring signal and the second measuring signal is greater than a difference of the maximum and the minimum measuring value of the present measurement arrangement.

19. The method according to claim 18, wherein determining a measurement arrangement as present measurement arrangement comprises reading out information regarding a measurement arrangement from a memory and determining the measurement arrangement as the present measurement arrangement to which the information stored in the memory refers.

20. The method according to claim 18, further comprising determining a further measurement arrangement, which is not the present measurement arrangement and not the comparison measurement arrangement, as the comparison measurement arrangement if the difference of the first measuring signal and the second measuring signal is smaller than or equal to a difference of the maximum and the minimum measuring value of the present measurement arrangement.

21. The method according to claim 18, wherein evaluating the detected measuring signals of the present measurement arrangement by determining a minimum measuring value and a maximum measuring value of the present measurement arrangement comprises comparing the detected measuring value with a previously detected measuring value of the present measurement arrangement, wherein a presence of a minimum or maximum measuring value is inferred if a difference value between the detected measuring value and the previously detected measuring value is smaller than or equal to, in terms of magnitude, a predetermined upper limit.

22. The method according to claim 18, wherein providing an output signal on the basis of the detected measuring signal of the present measurement arrangement comprises outputting the output signal at a terminal of the magnetic-field sensor.

23. The method according to claim 18, further comprising storing information regarding the present measurement arrangement.

24. The method according to claim 18, wherein determining a measurement arrangement as present measurement arrangement comprises reading out information regarding a measurement arrangement from a memory and determining the measurement arrangement to which the information stored in the memory refers as the present measurement arrangement, further storing information regarding the present measurement arrangement in the memory only if the comparison measurement arrangement has been determined as the present measurement arrangement at least once.

25. A method of calibrating a magnetic-field sensor comprising a plurality of sensor elements connected to form a measurement arrangement, each measurement arrangement comprising a measurement tap, and wherein the magnetic-field sensor is exposed to a magnetic field periodically changing at least in portions, comprising:

determining a measurement arrangement sequence comprising at least one measurement arrangement;

supplying the measurement arrangements of the measurement arrangement sequence with an excitation signal, to generate a tappable measuring signal at the center taps of the measurement arrangements of the measurement arrangement sequence;

detecting measuring signals of the measurement arrangements of the measurement arrangement sequence;

providing an output signal on the basis of the detected measuring signals of the measurement arrangements of the measurement arrangement sequence;

evaluating the individual measuring signals of the measurement arrangement sequence by comparing the individual measuring signals and the output signal on the basis of a comparison relationship; and

modifying the measurement arrangement sequence if evaluating a measuring signal of a measurement arrangement on the basis of the comparison relationship does not satisfy a comparison condition.

26. The method according to claim 25, wherein determining a measurement arrangement sequence comprises determining a measurement arrangement sequence comprising a plurality of measurement arrangements.

27. The method according to claim 25, wherein detecting measuring signals of the measurement arrangements of the measurement arrangement sequence comprises sequentially coupling the measurement taps of each measurement arrangement of the measurement arrangement sequence if the measurement arrangement sequence comprises more than one measurement arrangement, and detecting a measuring signal of the coupled measurement arrangement.

28. The method according to claim 25, wherein providing the output signal on the basis of the detected measuring signals of the measurement arrangements of the measurement arrangement sequence comprises averaging the detected measuring signals of all measurement arrangements of the measurement arrangement sequence.

29. The method according to claim 28, wherein averaging the detected measuring signals comprises arithmetically averaging the detected measuring signals of the measurement arrangements of the measurement arrangement sequence, taking the number of measurement arrangements of the measurement arrangement sequence into account.

30. The method according to claim 25, wherein evaluating the individual measuring signals of the measurement arrangements of the measurement arrangement sequence comprises comparing the individual measuring signals and the output signal on the basis of minimum and maximum values of the individual measuring signals and the output signal.

31. The method according to claim 30, wherein modifying the measurement arrangement sequence comprises removing an examined measurement arrangement from the measurement arrangement sequence if a difference of the maximum and minimum measuring signal of the examined measurement arrangement is smaller than a product of a factor and a difference of the maximum and the minimum output signal.

32. The method according to claim 25, wherein modifying the measurement arrangement sequence comprises removing an examined measurement arrangement from the measurement arrangement sequence if a difference of the maximum and the minimum measuring signal of the examined measurement arrangement is smaller than a difference of a maximum and a minimum measuring signal of the other measurement arrangements, which are not the examined measurement arrangement, if the measurement arrangement sequence comprises at least one further measurement arrangement apart from the examined measurement arrangement.

33. The method according to claim 25, wherein determining a measurement arrangement sequence comprises reading out information regarding the measurement arrangement sequence from a memory and determining the measurement arrangement sequence on the basis of the measurement arrangement to which the information stored in the memory refers.

34. The method according to claim 25, further comprising storing the measurement arrangement sequence in a memory.

35. 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.

36. The magnetic-field sensor according to claim 35, 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.

37. The magnetic-field sensor according to claim 35, 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 measuring signals of at least two measurement arrangements over at least one period of a magnetic field periodically changing at least in portions, further formed to evaluate the detected measuring signals by determining the respective maximum and minimum measuring values of the detected measuring signals, and formed to determine the measurement arrangement with the greatest difference of the respective maximum and minimum measuring values.

38. The magnetic-field sensor according to claim 35, wherein the control circuit is formed to determine a measurement arrangement as present measurement arrangement, further formed to determine a further measurement bridge, which is not the present measurement arrangement, as comparison measurement arrangement, further formed to supply the present measurement arrangement and the comparison measurement arrangement with an excitation signal to generate a tappable measuring signal at the measurement taps of the present measurement arrangement and the comparison measurement arrangement, formed to detect measuring signals of the present measurement arrangement, further formed to provide an output signal on the basis of the detected measuring signal of the present measurement arrangement, further formed to evaluate the detected measuring signals of the present measurement arrangement by determining a minimum measuring value and a maximum measuring value of the present measurement arrangement, further formed to detect a first measuring signal of the comparison measurement arrangement if a detected measuring signal of the present measurement arrangement corresponds to the maximum measuring value of the present measurement arrangement, further formed to detect a second measuring signal of the comparison measurement arrangement if a detected measuring signal of the present measurement arrangement corresponds to the minimum measuring value of the present measurement arrangement, and further formed to determine the comparison measurement arrangement as the present measurement arrangement if a difference of the first measuring signal and the second measuring signal is greater than a difference of the maximum and the minimum measuring value of the present measurement arrangement.

39. The magnetic-field sensor according to claim 35, wherein the control circuit is formed to determine a measurement arrangement sequence comprising at least one measurement arrangement, further formed to supply the measurement arrangements of the measurement arrangement sequence with an excitation signal to generate a tappable measuring signal at the measurement taps of the measurement arrangements of the measurement arrangement sequence, further formed to detect measuring signals of the measurement arrangements of the measurement arrangement sequence, further formed to provide an output signal on the basis of the detected measuring signals of the measurement arrangements of the measurement arrangement sequence, further formed to evaluate the individual measuring signals of the measurement arrangements of the measurement arrangement sequence by comparing the individual measuring signals and the output signal on the basis of a comparison relationship, and further formed to modify the measurement arrangement sequence if evaluating a measuring signal of a measurement arrangement on the basis of the comparison relationship does not satisfy a comparison condition.

40. The magnetic-field sensor according to claim 35, wherein the measurement arrangements each comprise at least one sensor element.

41. The magnetic-field sensor according to claim 35, wherein a common sensor element belongs to two different measurement arrangements.

42. The magnetic-field sensor according to claim 35, wherein the measurement arrangements comprise a series connection of two sensor elements with a measurement tap connected between the two sensor elements.

43. The magnetic-field sensor according to claim 35, 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.

44. The magnetic-field sensor according to claim 35, wherein the sensor elements are arranged on a chip of the magnetic-field sensor in a manner shifted laterally with respect to each other.

45. The magnetic-field sensor according to claim 35, wherein the sensor elements are magnetoresistive sensor elements.

46. The magnetic-field sensor according to claim 35, 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.

47. The magnetic-field sensor according to claim 35, wherein the control circuit comprises an analog/digital converter which can be coupled to at least one center tap of a measurement arrangement.

48. The magnetic-field sensor according to claim 46, 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.

49. The magnetic-field sensor according to claim 35, wherein the control circuit further comprises a pre-processing circuit formed to filter detected measuring signals.

50. The magnetic-field sensor according to claim 35, 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.

51. The magnetic-field sensor according to claim 35, 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.

52. The magnetic-field sensor according to claim 35, wherein the control circuit further comprises a reference measurement arrangement with a reference tap, and wherein the reference measurement arrangement comprises a resistive element.

53. The magnetic-field sensor according to claim 35, wherein the control circuit further comprises a memory allowing for non-volatile storage or one-time storage of information.

54. A magnetic-field sensor, comprising:

a plurality of magnetoresistive 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 arrangement and further comprising a memory into which information regarding a measurement arrangement can be written once and from which the same can be read out multiple times,

wherein the control circuit is formed to store in the memory information regarding a measurement arrangement determined for measurement operation.

55. The magnetic-field sensor according to claim 54, wherein the measurement arrangements each comprise at least one magnetoresistive sensor element.

56. The magnetic-field sensor according to claim 54, wherein two different measurement arrangements comprise a common magnetoresistive sensor element.

57. The magnetic-field sensor according to claim 54, wherein the magnetoresistive sensor elements are arranged on a chip of the magnetic-field sensor in a manner shifted laterally with respect to each other.

58. The magnetic-field sensor according to claim 54, wherein the control circuit is further formed to read out the information regarding the determined measurement arrangement from the memory in a measurement operation of the magnetic-field sensor, and further formed to provide an evaluation signal on the basis of a measuring signal of the determined measurement arrangement in the measurement operation.

59. 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.

60. 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, and wherein the magnetic-field sensor is exposed to a magnetic field periodically changing at least in portions, the method comprising supplying the measurement arrangements with an excitation signal, to generate a tappable measuring signal at each measurement tap of the measurement arrangement, detecting the measuring signals of at least two measurement arrangements over at least one period of the magnetic field, evaluating the detected measuring signals by determining the respective maximum and minimum measuring values of the detected measuring signals, and determining the measurement arrangement with the greatest difference of the respective maximum and minimum measuring values.

61. 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, wherein the magnetic-field sensor is exposed to a magnetic field periodically changing at least in portions, the method comprising determining a measurement arrangement as present measurement arrangement, determining a further measurement arrangement as comparison measurement arrangement, which is not the present measurement arrangement, supplying the present measurement arrangement and the comparison measurement arrangement with an excitation signal, to generate a tappable measuring signal at the measurement arrangement of the present measurement arrangement and the comparison measurement arrangement, detecting measuring signals of the present measurement arrangement, providing an output signal on the basis of the detected measuring signal of the present measurement arrangement, evaluating the detected measuring signals of the present measurement arrangement by determining a minimum measuring value and a maximum measuring value of the present measurement arrangement, detecting a first measuring value of the comparison measurement arrangement if a detected measuring signal of the present measurement arrangement corresponds to the maximum measuring value of the present measurement arrangement, detecting a second measuring signal of the comparison measurement arrangement if a detected measuring signal of the present measurement arrangement corresponds to the minimum measuring value of the present measurement arrangement, and determining the comparison measurement arrangement as the present measurement arrangement if a difference of the first measuring signal and the second measuring signal is greater than a difference of the maximum and the minimum measuring value of the present measurement arrangement.

62. 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 a measurement arrangement, each measurement arrangement comprising a measurement tap, and wherein the magnetic-field sensor is exposed to a magnetic field periodically changing at least in portions, the method comprising determining a measurement arrangement sequence comprising at least one measurement arrangement, supplying the measurement arrangements of the measurement arrangement sequence with an excitation signal, to generate a tappable measuring signal at the center taps of the measurement arrangements of the measurement arrangement sequence, detecting measuring signals of the measurement arrangements of the measurement arrangement sequence, providing an output signal on the basis of the detected measuring signals of the measurement arrangements of the measurement arrangement sequence, evaluating the individual measuring signals of the measurement arrangement sequence by comparing the individual measuring signals and the output signal on the basis of a comparison relationship, and modifying the measurement arrangement sequence if evaluating a measuring signal of a measurement arrangement on the basis of the comparison relationship does not satisfy a comparison condition.