FREQUENCY DOUBLING OF XMR SIGNALS

• US 20130241544A1
• Filed: 03/15/2012
• Published: 09/19/2013
• Est. Priority Date: 03/15/2012
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Zimmer, Juergen
• Granted Patent: US 9,817,085 B2
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: G01D 5/2451 Incremental encoders G01D5/2454 takes precedence
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors
• CPC Class Codes: G01P 3/489 Digital circuits therefor
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors

Abstract

Embodiments relate to sensors, such as speed sensors and angle sensors, that use a modulated supply voltage to approximately double output signals of the sensors because the sensor element and the supply voltage exhibit the same frequency. In embodiments, the sensor element is an xMR element, and the modulated supply voltage is generated on-chip, such as by another xMR element. Direct frequency doubling of the output signal of the sensor element therefore can be obtained without additional and complex circuitry or signal processing.

Claims

1. A sensor system comprising:

a magnetic field source;

a magnetoresistive sensor configured to provide an output signal related to the magnetic field source, the output signal having a frequency; and

a voltage supply coupled to the sensor element to provide a modulated supply voltage having a frequency the same as the frequency of the sensor element output signal.

2. The sensor system of claim 1, wherein the modulated supply voltage doubles the frequency of the output signal as compared with an unmodulated supply voltage.

3. The sensor system of claim 1, wherein the sensor comprises a first half-bridge configuration of sensor elements and a second half-bridge configuration of sensor elements forming a first Wheatstone bridge configuration of sensor elements, and a second Wheatstone bridge configuration of sensor elements arranged between the first and second half-bridge configurations.

4. The sensor system of claim 3, wherein an output signal of the second Wheatstone bridge configuration of sensor elements is provided to a supply voltage input of the first Wheatstone bridge configuration of sensor elements to provide the modulated supply voltage.

5. The sensor system of claim 4, further comprising an amplifier, wherein the output signal of the second Wheatstone bridge configuration is provided to the supply voltage input of the first Wheatstone bridge configuration of sensor elements via the amplifier.

6. The sensor system of claim 1, wherein the sensor comprises at least one of a giant magnetoresistive sensor element (GMR), a tunneling magnetoresistive sensor element (TMR) or an anisotropic magnetoresistive sensor element (AMR).

7. The sensor system of claim 1, wherein the sensor comprises first, second and third Wheatstone bridge configurations of sensor elements, wherein an output signal of the first bridge configuration is phase-shifted by 90 degrees with respect to an output signal of the second bridge configuration, wherein an output signal of the third bridge configuration has substantially the same phase as one of the output signals of the first or second bridge configurations, and wherein the output signal of the third bridge configuration is provided to a supply voltage input of the first and second bridge configurations to provide the modulated supply voltage.

8. The sensor system of claim 7, further comprising an amplifier, wherein the output signal of the third bridge configuration is provided to the supply voltage input of the first and second bridge configurations via the amplifier.

9. The sensor system of claim 7, further comprising a switch configured to switch the supply voltage input of the first and second bridge configurations between the modulated supply voltage and a constant supply voltage.

10. A method comprising:

providing a sensor having a response to an external magnetic field; and

providing a supply voltage to the sensor having substantially the same frequency as the response of the sensor.

11. The method of claim 10, wherein providing a sensor comprises providing a first sensor configuration and a second sensor configuration, and wherein providing a supply voltage comprises modulating the supply voltage to the first sensor configuration by an output of the second sensor configuration.

12. The method of claim 11, further comprising doubling a frequency of the response of the sensor by the modulating.

13. The method of claim 11, wherein providing the supply voltage comprises amplifying the output of the second sensor configuration.

14. The method of claim 11, wherein providing a first sensor configuration and a second sensor configuration comprises providing first and second Wheatstone bridge sensor configurations.

15. The method of claim 14, wherein providing first and second Wheatstone bridge sensor configurations comprises arranging the second Wheatstone bridge configuration between first and second half-bridges of the first Wheatstone bridge configuration.

16. The method of claim 14, further comprising providing a third Wheatstone bridge sensor configuration.

17. The method of claim 10, wherein providing a sensor comprises providing a magnetoresistive sensor.

18. The method of claim 14, wherein providing a magnetoresistive sensor comprises providing at least one of a giant magnetoresistive sensor (GMR), a tunneling magnetoresistive sensor (TMR) or an anisotropic magnetoresistive sensor (AMR).

19. A sensor system comprising:

a magnetoresistive sensor comprising a first sensor element configuration and a second sensor element configuration; and

a voltage supply coupled to the sensor to provide a supply voltage modulated by an output signal of the second sensor element configuration to the first sensor element configuration.

20. The sensor system of claim 19, further comprising a magnetic field source.

21. The sensor system of claim 20, wherein a frequency of the modulated supply voltage is substantially the same as a frequency of the output signal of the second sensor element when the magnetic field source provides a varying magnetic field.

22. The sensor system of claim 19, further comprising amplifier circuitry to amplify the output signal of the second sensor element.

23. The sensor system of claim 19, wherein the magnetoresistive sensor comprises at least one of a giant magnetoresistive sensor (GMR), a tunneling magnetoresistive sensor (TMR) or an anisotropic magnetoresistive sensor (AMR).

24. A sensor system for measuring a parameter of a rotating magnetic field comprising:

a first magnetoresistive (xMR) sensor bridge; and

a second xMR sensor bridge, wherein the first and second xMR sensor bridges are coupled to each other such that a signal tapped from the first xMR sensor bridge has double a frequency of the rotating magnetic field.

25. The sensor system of claim 24, wherein the first and second xMR sensor bridges are coupled to each other such that at least one operating parameter of the first xMR sensor bridge is influenced by the second xMR sensor bridge.

26. The sensor system of claim 25, wherein a change in the frequency of the rotating magnetic field produces a corresponding change in the at least one operating parameter.

27. A sensor system for determining at least one parameter of rotation of a magnetic field comprising:

a magnetoresistive (xMR) sensor bridge arrangement comprising first and second xMR sensor bridges configured such that an analog output signal of the xMR sensor bridge arrangement has a signal frequency double a frequency of the rotation of the magnetic field.