Electronic Circuit Configured to Reset a Magnetoresistance Element

• US 20100026289A1
• Filed: 07/31/2008
• Published: 02/04/2010
• Est. Priority Date: 07/31/2008
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Taylor, William P., Doogue, Michael C.
• Granted Patent: US 7,973,527 B2
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 15/205 using magneto-resistance devices, e.g. field plates
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00

Abstract

An electronic circuit includes a magnetoresistance element for providing an output signal proportional to a magnetic field. The magnetoresistance element also has a hysteresis characteristic. The electronic circuit also includes at least one of a reset conductor or a bias conductor disposed proximate to the magnetoresistance element. For embodiments having a reset conductor, the electronic circuit is configured to generate a reset current carried by the reset conductor in response to the comparison. In response to the reset current, the reset conductor is configured to generate a reset magnetic field at the magnetoresistance element to temporarily force the magnetoresistance element to a saturation region of the hysteresis characteristic.

Claims

1. An electronic circuit, comprising:

a magnetoresistance element for providing an output signal proportional to a magnetic field, wherein the magnetoresistance element has a maximum response axis, and wherein the magnetoresistance element has a hysteresis characteristic;

a reset conductor disposed proximate to the magnetoresistance element; and

a comparison circuit coupled to receive the output signal, configured to compare the output signal to a threshold signal; and

configured to generate a reset current carried by the reset conductor in response to the comparison, wherein, in response to the reset current, the reset conductor is configured to generate a reset magnetic field at the magnetoresistance element to temporarily force the magnetoresistance element to a saturation region of the hysteresis characteristic.

2. The electronic circuit of claim 1, wherein the magnetoresistance element comprises a giant magnetoresistance element.

3. The electronic circuit of claim 1, wherein the magnetoresistance element comprises two magnetoresistance elements.

4. The electronic circuit of claim 3, wherein the two magnetoresistance elements as arranged in the electronic circuit have opposite responses to a magnetic field.

5. The electronic circuit of claim 3, wherein the reset magnetic field is generated so as to temporarily force one of the two magnetoresistance elements to a highest resistance and the other one of the two miiagnetoresistance elements to a lowest resistance.

6. The electronic circuit of claim 3, wherein the reset magnetic field is generated so as to temporarily force both of the two magnetoresistance elements to a highest resistance or to a lowest resistance.

7. The electronic circuit of claim 1, further comprising a current-carrying conductor disposed proximate to the magnetoresistance element, wherein the output signal is proportional to a sensed current magnetic field generated by a current carried by the current-carrying conductor, wherein the electronic circuit is configured as a current sensor.

8. The electronic circuit of claim 1, wherein the reset conductor comprises a coil.

9. The electronic circuit of claim 1, wherein the comparison circuit comprises:

a comparator coupled to receive the output signal, coupled to receive the threshold signal, and configured to generate a comparison signal; and

a monostable multivibrator coupled to receive the comparison signal and configured to generate the reset current.

10. The electronic circuit of claim 1, further comprising a bias magnetic field generating module, wherein the bias magnetic field generating module is configured to continuously generate a bias magnetic field at the magnetoresistance element to continually force the magnetoresistance element to a transition region of the hysteresis characteristic in the absence of any other magnetic field.

11. The electronic circuit of claim 10, wherein the bias magnetic field generating module comprises a permanent magnet disposed proximate to the magnetoresistance element.

12. The electronic circuit of claim 10, wherein the bias magnetic field generating module comprises:

a current source configured to generate a bias current; and

a bias conductor coupled to carry the bias current and disposed proximate to the magnetoresistance element.

13. The electronic circuit of claim 1, wherein the hysteresis characteristic is a function of resistance versus an applied magnetic field and a graph of the hysteresis characteristic has two linear regions coupled by two saturation regions.

14. The electronic circuit of claim 1, wherein the hysteresis characteristic is a function of resistance versus an applied magnetic field and a graph of the hysteresis characteristic has a shape comprising two overlapping curves.

15. An electronic circuit, comprising:

a magnetoresistance element for providing an output signal proportional to a magnetic field, wherein the magnetoresistance element has a maximum response axis, and wherein the magnetoresistance element has a hysteresis characteristic; and

a first bias magnetic field generating module, wherein the first bias magnetic field generating module is configured to continuously generate a first bias magnetic field at the magnetoresistance element to continually force the magnetoresistance element to a transition region of the hysteresis characteristic in the absence of any other magnetic field.

16. The electronic circuit of claim 15, wherein the first bias magnetic field generating module comprises a permanent magnet disposed proximate to the magnetoresistance element.

17. The electronic circuit of claim 15, wherein the first bias magnetic field generating module comprises:

a current source configured to generate a bias current; and

a bias conductor coupled to carry the bias current and disposed proximate to the magnetoresistance element.

18. The electronic circuit of claim 15, further comprising a second bias magnetic field generating module, wherein the second bias magnetic field generating module is configured to continuously generate a second bias magnetic field at the magnetoresistance element in response to a predetermined deviation of the output signal.

19. The electronic circuit of claim 15, wherein the magnetoresistance element comprises a giant magnetoresistance element.

20. The electronic circuit of claim 15, wherein the magnetoresistance element comprises two magnetoresistance elements.

21. The electronic circuit of claim 20, wherein the two magnetoresistance elements as arranged in the electronic circuit have opposite responses to a magnetic field.

22. The electronic circuit of claim 15, further comprising a current-carrying conductor disposed proximate to the magnetoresistance element, wherein the output signal is proportional to a sensed current magnetic field generated by a current carried by the current-carrying conductor, wherein the electronic circuit is configured as a current sensor.

23. The electronic circuit of claim 15, wherein the hysteresis characteristic is a function of resistance versus an applied magnetic field and a graph of the hysteresis characteristic two linear regions coupled by two saturation regions.

24. The electronic circuit of claim 15, wherein the hysteresis characteristic is a function of resistance versus an applied magnetic field and a graph of the hysteresis characteristic has a shape comprising two overlapping curves.