Magnetic field sensors and associated methods with reduced offset and improved accuracy

Patent metadata

Field	Value
Publication number	US-9753097-B2
Application number	US-201414269973-A
Country	US
Kind code	B2
Filing date	May 5, 2014
Priority date	May 5, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A magnetic field sensor with a plurality of magnetic field sensing elements is provided herein. The magnetic field sensor includes a circular vertical Hall (CVH) sensing element comprising a plurality of vertical Hall elements arranged over a common implant and diffusion region in a substrate, 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 includes a sequence switches circuit coupled to the plurality of vertical Hall elements, wherein the sequences switches circuit is operable to select from among the plurality of vertical Hall elements, wherein each selected one of the one or more of the plurality of vertical Hall elements comprises a respective plurality of active vertical Hall element contacts and at least one respective skipped contact, the at least one skipped contact disposed between at least one respective pair of active vertical Hall element contacts, wherein a position of the at least one skipped contact is selected to reduce an offset voltage of a respective one of the plurality of vertical Hall elements. An associated method is also disclosed herein.

First claim

What is claimed is:

1. A magnetic field sensor, comprising:
a circular vertical Hall (CVH) sensing element comprising:
a plurality of vertical Hall elements arranged over a common implant and diffusion region in a substrate, 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 sequence switches circuit is operable to select from among the plurality of vertical Hall elements, and wherein the sequence switches circuit is configured to supply a current signal or a voltage signal to the plurality of vertical Hall elements, wherein each selected one of the plurality of vertical Hall elements comprises a respective plurality of active vertical Hall element contacts and at least one respective skipped contact, the at least one skipped contact disposed between at least one respective pair of the respective plurality of active vertical Hall element contacts, wherein a position of the at least one skipped contact is selected to reduce an offset voltage of a respective one of the plurality of vertical Hall elements,
wherein the respective at least one skipped contact for each selected one of the plurality of vertical Hall elements is not coupled to receive the current signal or the voltage signal, is not configured to couple to a reference potential, and an output signal of the sequence switches circuit is not configured to be generated by the respective at least one skipped contact.

2. The magnetic field sensor of claim 1 , further comprising:
a control circuit configured to provide a control signal to the sequence switches circuit for sequential selection from among the plurality of vertical Hall elements.

3. The magnetic field sensor of claim 1 , wherein the at least one skipped contact comprises two skipped contact.

4. The magnetic field sensor of claim 1 , wherein the at least one skipped contact comprises a pair of skipped contacts symmetrically surrounding a center active vertical Hall element contact of each selected one of the plurality of vertical Hall elements.

5. The magnetic field sensor of claim 1 , wherein the at least one skipped contact comprises a pair of skipped contacts, each skipped contact proximate to a last active vertical Hall element contact of each selected one of the plurality of vertical Hall elements.

6. The magnetic field sensor of claim 1 , wherein the plurality of vertical Hall elements overlap and share select vertical Hall element contacts with an adjacent selected one of the plurality of vertical Hall elements.

7. The magnetic field sensor of claim 1 , wherein at least one of the vertical Hall element contacts of the plurality of vertical Hall elements is selected from a non-adjacent selected one of the plurality of vertical Hall elements.

8. The magnetic field sensor of claim 1 , wherein a position of the at least one skipped vertical Hall element contact is selected based upon a conformal mapping of a respective selected one of the plurality of vertical Hall elements.

9. The magnetic field sensor of claim 8 , wherein a distance between the active vertical Hall element contacts of each selected one of the plurality of vertical Hall elements is unequal and wherein a resistance between the active vertical Hall element contacts of each selected one of the selected plurality of vertical Hall elements is unequal.

10. The magnetic field sensor of claim 1 , wherein each one of the active vertical Hall element contacts of each selected one of the plurality of vertical Hall elements is associated with a respective vertical resistance and a respective horizontal resistance, and wherein a position of the at least one skipped contact results in an increase in the horizontal resistance.

11. The magnetic field sensor of claim 4 , wherein each one of the active vertical Hall element contacts of each selected one of the plurality of vertical Hall elements is associated with a respective vertical resistance and a respective horizontal resistance, and wherein a position of the pair of skipped contacts results in an increase in the horizontal resistance.

12. The magnetic field sensor of claim 1 , wherein the at least one skipped contact comprises four skipped contacts.

13. 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 arranged over a common implant and diffusion region in a substrate, each magnetic field signal being responsive to a magnetic field;
selecting from among the plurality of vertical Hall elements with a sequence switches circuit, wherein the sequence switches circuit is configured to supply a current signal or a voltage signal to the plurality of vertical Hall elements, wherein each selected one of the plurality of vertical Hall elements comprises a respective plurality of active vertical Hall element contacts and at least one respective skipped contact, the at least one skipped contact disposed between at least one respective pair of the respective plurality of active vertical Hall element contacts, wherein a position of the at least one skipped contact is selected to reduce an offset voltage of a respective one of the plurality of vertical Hall elements,
wherein the respective at least one skipped contact for each selected one of the plurality of vertical Hall elements is not coupled to receive the current signal or the voltage signal, is not configured to couple to a reference potential, and an output signal of the sequence switches circuit is not configured to be generated by the respective at least one skipped contact.

14. The method of claim 13 , further comprising:
sequentially selecting from among the plurality of vertical Hall elements.

15. The method of claim 13 , wherein the at least one skipped contact comprises two skipped contacts.

16. The method of claim 13 , wherein the at least one skipped contact comprises a pair of skipped contacts symmetrically surrounding a center active vertical Hall element contact of each selected one of the plurality of vertical Hall elements.

17. The method of claim 13 , wherein the at least one skipped contact comprises a pair of skipped contacts, each skipped contact of the pair proximate to a last active vertical Hall element contact of each selected one of the plurality of vertical Hall elements.

18. The method of claim 13 , wherein the plurality of vertical Hall elements overlap and share select vertical Hall element contacts with an adjacent selected one of the plurality of vertical Hall elements.

19. The method of claim 13 , wherein at least one of the vertical Hall element contacts of the plurality of vertical Hall elements is selected from a non-adjacent selected one of the plurality of vertical Hall elements.

20. The method of claim 13 , wherein a position of the at least one skipped vertical Hall element contact is selected based upon a conformal mapping of a respective selected one of the plurality of vertical Hall elements.

21. The method of claim 20 , wherein a distance between the active vertical Hall element contacts of each selected one of the plurality of vertical Hall elements is unequal and wherein a resistance between the active vertical Hall element contacts of each selected one of the plurality of vertical Hall elemen

Assignees

• Allegro Microsystems Llc

Inventors

• Romero Hernan D

Classifications

• G01R33/0029 Primary

  Treating the measured signals, e.g. removing offset or noise · CPC title

• G01R33/077

  Vertical Hall-effect devices · CPC title