Magnetic field sensor with improved accuracy and method of obtaining improved accuracy with a magnetic field sensor

• US 9,684,042 B2
• Filed: 02/27/2015
• Issued: 06/20/2017
• Est. Priority Date: 02/27/2015
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Diaconu, Aurelian
• Primary Examiner(s): Le, Son
• Assistant Examiner(s): DICKINSON, DUSTIN R
• Application Number:
  US14/633,190
• Publication Number:
  US 20160252590A1
• Time in Patent Office: 844 Days
• CPC Class Codes: G01D 5/142 using Hall-effect devices measuring magnetic variables using Hall-effect or other galvanomagnetic devices G01R33/06
• CPC Class Codes: G01R 33/0023 Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration G01R33/0017 takes precedence
• CPC Class Codes: G01R 33/077 Vertical Hall-effect devices

Abstract

A magnetic field sensor includes a circular vertical Hall (CVH) sensing element comprising a plurality of vertical Hall elements, each one of the plurality of vertical hall elements comprising respective first and second current receiving contacts. The magnetic field sensor additionally includes a sequence switches circuit coupled to the plurality of vertical Hall elements. The magnetic field sensor also includes a first current source sequentially coupled by the sequence switches circuit to the first current receiving contact of sequentially selected ones of the plurality of vertical Hall elements. The magnetic field sensor further includes a second current source sequentially coupled by the sequence switches circuit to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements. The first and second current sources can swap couplings in half-period intervals for each of a plurality of coupling arrangements. A corresponding method is also described.

Claims

1. A magnetic field sensor, comprising:

a circular vertical Hall (CVH) sensing element comprising;

a plurality of vertical Hall elements, each one of the plurality of vertical hall elements comprising respective first and second current receiving contacts, respective first and second output signal generating contacts, and a respective at least one reference contact, wherein the at least one reference contact is positioned between the first and second current receiving contacts, the first output signal generating contact is positioned between the at least one reference contact and the first current receiving contact, and the second output signal generating contact is positioned between the at least one reference contact and the second current receiving contact;

wherein the plurality of vertical Hall elements is configured to generate a plurality of magnetic field signals, each magnetic field signal responsive to a magnetic field;

the magnetic field sensor further comprising;

a sequence switches circuit coupled to the plurality of vertical Hall elements, wherein the sequences switches circuit is operable to sequentially select from among the plurality of vertical Hall elements to generate sequenced signal steps;

a first current source sequentially coupled by the sequence switches circuit to the first current receiving contact of sequentially selected ones of the plurality of vertical Hall elements, and operable to provide, at first sequential times, a first current signal to the first current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements;

a second current source sequentially coupled by the sequence switches circuit to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements and operable to provide, at the same first sequential times, a second current signal to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements; and

an amplifier circuit coupled to receive the sequenced signal steps produced at the first and second output signal generating contacts of the sequentially selected ones of the plurality of vertical Hall elements, and, in response to the sequenced signal steps, the amplifier circuit is configured to generate an amplified signal representative of sequentially selected ones of the plurality of magnetic field signals,

wherein the first current source is sequentially coupled by the sequence switches circuit to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements, and operable to provide, at second sequential times, the first current signal to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements; and

wherein the second current source is sequentially coupled by the sequence switches circuit to the first current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements, and operable to provide, at the same second sequential times, the second current signal to the first current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements.

2. The magnetic field sensor of claim 1, wherein the vertical Hall elements are not configured in a current spinning arrangement.

3. The magnetic field sensor of claim 1, wherein the first current signal and the second current signal are substantially equal in magnitude.

4. The magnetic field sensor of claim 1, wherein the amplifier circuit is coupled to the select first and second output generating contacts in a Kelvin connection arrangement.

5. The magnetic field sensor of claim 1, wherein an input impedance of the amplifier circuit is substantially more than an output impedance of the first and second output generating contacts of the sequentially selected ones of the plurality of vertical Hall elements.

6. The magnetic field sensor of claim 1, wherein each selected one of the plurality of vertical Hall elements comprises five vertical Hall element contacts.

7. The magnetic field sensor of claim 1, wherein the at least one reference contact is coupled to a reference potential.

8. The magnetic field sensor of claim 7, wherein the reference potential is ground.

9. The magnetic field sensor of claim 1, wherein the first current signal and the second current signal are substantially unequal in magnitude.

10. A method, comprising:

generating a plurality of magnetic field signals with a circular vertical Hall (CVH) sensing element, the CVH sensing element comprising a plurality of vertical Hall elements, each one of the plurality of vertical hall elements comprising respective first and second current receiving contacts, respective first and second output signal generating contacts, and a respective at least one reference contact, wherein the at least one reference contact is positioned between the first and second current receiving contacts, the first output signal generating contact is positioned between the at least one reference contact and the first current receiving contact, and the second output signal generating contact is positioned between the at least one reference contact and the second current receiving contact, each magnetic field signal being responsive to a magnetic field;

sequentially selecting from among the plurality of vertical Hall elements;

generating a first current signal and providing, at first sequential times, the first current signal to the first current receiving contact of sequentially selected ones of the plurality of vertical Hall elements;

generating a second current signal and providing, at the same first sequential times, the second current signal to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements;

generating a first sequenced signal step, responsive to an external magnetic field, at the first and second output generating contacts of the sequentially selected ones of the plurality of vertical Hall elements;

generating the first current signal and providing, at second sequential times, the first current signal to the second current receiving contact of sequentially selected ones of the plurality of vertical Hall elements;

generating the second current signal and providing, at the same second sequential times, the second current signal to the first current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements;

generating a second sequenced signal step, responsive to the external magnetic field, at the first and second output generating contacts of the sequentially selected ones of the plurality of vertical Hall elements; and

generating an amplified signal representative of sequentially selected ones of the plurality of magnetic field signals in response to at least the first and second sequenced signal steps.

11. The method of claim 10, wherein the first current signal and the second current signal are substantially equal in magnitude.

12. The method of claim 10, wherein each selected one of the plurality of vertical Hall elements comprises five vertical Hall element contacts.

13. The method of claim 10, wherein the at least one reference contact is coupled to a reference potential.

14. The method of claim 13, wherein the reference potential is ground.

15. The method of claim 10, wherein the first current signal and the second current signal are substantially unequal in magnitude.

16. A magnetic field sensor, comprising:

a circular vertical Hall (CVH) sensing element comprising;

a plurality of vertical Hall elements, each one of the plurality of vertical hall elements comprising respective first and second current receiving contacts, respective first and second output signal generating contacts, and a respective at least one reference contact, wherein the at least one reference contact is positioned between the first and second current receiving contacts, the first output signal generating contact is positioned between the at least one reference contact and the first current receiving contact, and the second output signal generating contact is positioned between the at least one reference contact and the second current receiving contact;

wherein the plurality of vertical Hall elements is configured to generate a plurality of magnetic field signals, each magnetic field signal responsive to a magnetic field;

the magnetic field sensor further comprising;

means for sequentially selecting from among the plurality of vertical Hall elements to generate sequenced signal steps;

means for providing, at first sequential times, a first current signal to the first current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements;

means for providing, at the same first sequential times, a second current signal to the second current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements;

means for providing, at second sequential times, the first current signal to the second current receiving contact of sequentially selected ones of the plurality of vertical Hall elements;

means for providing, at the same second sequential times, the second current signal to the first current receiving contact of the sequentially selected ones of the plurality of vertical Hall elements; and

means for generating an amplified signal representative of sequentially selected ones of the plurality of magnetic field signals in response to receiving the sequenced signal steps produced at the first and second output signal generating contacts of the sequentially selected ones of the plurality of vertical Hall elements.

17. The magnetic field sensor of claim 16, wherein the first current signal and the second current signal are substantially equal in magnitude.

18. The magnetic field sensor of claim 16, wherein the means for generating an amplified signal is coupled to the select first and second output generating contacts in a Kelvin connection arrangement.

19. The magnetic field sensor of claim 16, wherein the first current signal and the second current signal are substantially unequal in magnitude.

20. The magnetic field sensor of claim 16, wherein each selected one of the plurality of vertical Hall elements comprises five vertical Hall element contacts.