Circuit and Method for Reducing an Offset Component of a Plurality of Vertical Hall Elements Arranged in a Circle

• US 20150198677A1
• Filed: 01/14/2014
• Published: 07/16/2015
• Est. Priority Date: 01/14/2014
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Romero, Hernan D.
• Granted Patent: US 9,547,048 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 33/0017 Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields
• CPC Class Codes: G01R 33/077 Vertical Hall-effect devices

Abstract

Output signals from two or more vertical Hall elements arranged in a circle are combined is ways that reduce an offset voltage as the two or more vertical Hall elements are sequenced to generated a sequential output signal.

Claims

1. A magnetic field sensor, comprising:

a plurality of vertical Hall elements arranged in a circle and formed as a corresponding plurality of sets of contacts among a plurality of contacts disposed upon a substrate, wherein the plurality of vertical Hall elements is configured to generate a corresponding plurality of vertical Hall element output signals, wherein each one of the plurality of vertical Hall elements is responsive to an external magnetic field having an external magnetic field direction, wherein each one of the vertical Hall element output signals comprises a respective external magnetic field component responsive to the external magnetic field and a respective offset error component;

a sequence switches circuit coupled to receive the plurality of vertical Hall element output signals and configured to select first and second vertical Hall elements from among the plurality of vertical Hall elements, the first vertical Hall element having a first selected set of contacts selected from among the plurality of sets of contacts and the second vertical Hall element having a second selected set of contacts selected from among the plurality of sets of contacts, wherein the first and second vertical Hall elements are configured to generate first and second vertical Hall element output signals, respectively, wherein the first vertical Hall element output signal has a first external magnetic field component responsive to the external magnetic field and a first offset component, and wherein the second vertical Hall element output signal has a second external magnetic field component responsive to the external magnetic field and a second offset component, wherein the sequence switches circuit is further configured to combine the first and second vertical Hall element output signals so that the first and second magnetic field components add constructively to generate a constructive signal; and

a current switches circuit coupled to receive a current signal and configured to provide a first one or more current signals to a first selected one or more contacts of the first selected set of contacts, wherein the first one or more current signals flow into or out of a central contact of the first selected set of contacts, and to provide a second one or more current signals to a second selected one or more contacts of the second selected set of contacts, wherein the second one or more current signals flow into or out of a contact proximate to a central contact of the second selected set of contacts, wherein the first and second selected one or more contacts of the first and second vertical Hall elements are representative of first and second different coupling phases, respectively, wherein the sequence switches circuit and the current switches circuit are configured to sequence around the plurality of vertical Hall elements, sequentially selecting the first and second vertical Hall elements as different ones of the plurality of vertical Hall elements in order to generate a constructive sequenced signal.

2. The magnetic field sensor of claim 1, wherein the plurality of contacts are disposed over a common implant and diffusion region in the substrate forming a circular vertical Hall (CVH) sensing element.

3. The magnetic field sensor of claim 2, wherein the sequence switches circuit is further configured to select third and fourth vertical Hall elements from among the plurality of vertical Hall elements, the third vertical Hall element having a third selected set of contacts selected from among the plurality of sets of contacts and the fourth vertical Hall element having a fourth selected set of contacts selected from among the plurality of sets of contacts, wherein the third and fourth vertical Hall elements are configured to generate third and fourth vertical Hall element output signals, respectively, wherein the third vertical Hall element output signal has a third external magnetic field component responsive to the external magnetic field and a third offset component, and wherein the fourth vertical Hall element output signal has a fourth external magnetic field component responsive to the external magnetic field and a fourth offset component, wherein the sequence switches circuit is further configured to combine the third and fourth vertical Hall element output signals together to generate a compensating signal.

4. The magnetic field sensor of claim 3, wherein the sequence switches circuit is configured to combine the third and fourth vertical Hall element output signals together such that the third and fourth external magnetic field components add destructively.

5. The magnetic field sensor of claim 3, wherein the sequence switches circuit is configured to combine the third and fourth vertical Hall element output signals together such that the third and fourth external magnetic field components add constructively.

6. The magnetic field sensor of claim 3, wherein the current switches circuit is further configured to provide a third one or more current signals to a third selected one or more contacts of the third selected set of contacts and to provide a fourth one or more current signals to a fourth selected one or more contacts of the fourth selected set of contacts, wherein the sequence switches circuit and the current switches circuit are configured to sequence around the plurality of vertical Hall elements, sequentially selecting the third and fourth vertical Hall elements as different ones of the plurality of vertical Hall elements in order to generate a compensating sequenced signal, wherein the magnetic field sensor further comprises:

a combining circuit coupled to the sequence switches circuit and configured to combine a first signal representative of the constructive sequenced signal and a second signal representative of the compensating sequenced signal to generate a combined sequenced signal.

7. The magnetic field sensor of claim 6, wherein the third one or more current signals flow into or out of a central contact of the third selected set of contacts, and wherein the fourth one or more current signals flow into or out of a central contact of the fourth selected set of contacts, wherein the third and fourth selected one or more contacts of the third and fourth vertical Hall elements are representative of the same coupling phase.

8. The magnetic field sensor of claim 6, wherein the third one or more current signals flow into or out of a contact proximate to a central contact of the third selected set of contacts, and wherein the fourth one or more current signals flow into or out of a contact proximate to a central contact of the fourth selected set of contacts.

9. The magnetic field sensor of claim 6, wherein the third one or more current signals flow into or out of a contact proximate to a central contact of the third selected set of contacts, and wherein the fourth one or more current signals flow into or out of a central contact of the fourth selected set of contacts, wherein the third and fourth selected one or more contacts of the third and fourth vertical Hall elements are representative of the different coupling phases.

10. The magnetic field sensor of claim 6, further comprising a phase adjustment module coupled between the sequence switches circuit and the combining circuit and configured to apply a predetermined phase adjustment to a selected one of the constructive sequenced signal or the compensating sequenced signal to generate a respective one of the first signal or the second signal.

11. The magnetic field sensor of claim 6, wherein the first and second vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

12. The magnetic field sensor of claim 11, wherein the third and fourth vertical Hall elements are disposed one hundred eighty degrees apart around the circle, wherein a line between centers of the first and second vertical Hall elements and a line between centers of the third and fourth vertical Hall elements are approximately ninety degrees apart.

13. The magnetic field sensor of claim 6, wherein the first and second vertical Hall elements are immediately adjacent to each other and the third and fourth vertical Hall elements are immediately adjacent to each other.

14. The magnetic field sensor of claim 13, wherein the first and fourth vertical Hall elements are disposed one hundred eighty degrees apart around the circle, and wherein the second and third vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

15. The magnetic field sensor of claim 6, wherein the first and fourth vertical Hall elements are disposed one hundred eighty degrees apart around the circle, and wherein the second and third vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

16. The magnetic field sensor of claim 2, wherein the first and second vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

17. The magnetic field sensor of claim 1, wherein the sequence switches circuit is further configured to select third and fourth vertical Hall elements from among the plurality of vertical Hall elements, the third vertical Hall element having a third selected set of contacts selected from among the plurality of sets of contacts and the fourth vertical Hall element having a fourth selected set of contacts selected from among the plurality of sets of contacts, wherein the third and fourth vertical Hall elements are configured to generate third and fourth vertical Hall element output signals, respectively, wherein the third vertical Hall element output signal has a third external magnetic field component responsive to the external magnetic field and a third offset component, and wherein the fourth vertical Hall element output signal has a fourth external magnetic field component responsive to the external magnetic field and a fourth offset component, wherein the sequence switches circuit is further configured to combine the third and fourth vertical. Hall element output signals together to generate a compensating signal.

18. The magnetic field sensor of claim 17, wherein the current switches circuit is further configured to provide a third one or more current signals to a third selected one or more contacts of the third selected set of contacts and to provide a fourth one or more current signals to a fourth selected one or more contacts of the fourth selected set of contacts, wherein the sequence switches circuit and the current switches circuit are configured to sequence around the plurality of vertical Hall elements, sequentially selecting the third and fourth vertical Hall elements as different ones of the plurality of vertical Hall elements in order to generate a compensating sequenced signal, wherein the magnetic field sensor further comprises:

a combining circuit coupled to the sequence switches circuit and configured to combine a first signal representative of the constructive sequenced signal and a second signal representative of the compensating sequenced signal to generate a combined sequenced signal.

19. The magnetic field sensor of claim 18, further comprising a phase adjustment module coupled between the sequence switches circuit and the combining circuit and configured to apply a predetermined phase adjustment to a selected one of the constructive sequenced signal or the compensating sequenced signal to generate a respective one of the first signal or the second signal.

20. A method used in a magnetic field sensor, the magnetic field sensor comprising a plurality of vertical Hall elements arranged as a circle and formed as a corresponding plurality of sets of contacts among a plurality of contacts disposed upon a substrate, wherein the plurality of vertical Hall elements is configured to generate a corresponding plurality of vertical Hall element output signals, wherein each one of the plurality of vertical Hall elements is responsive to an external magnetic field having an external magnetic field direction, wherein each one of the vertical Hall element output signals comprises a respective external magnetic field component responsive to the external magnetic field and a respective offset error component, wherein the method comprises:

selecting first and second vertical Hall elements from among the plurality of vertical Hall elements, the first vertical Hall element having a first selected set of contacts selected from among the plurality of sets of contacts and the second vertical Hall element having a second selected set of contacts selected from among the plurality of sets of contacts, wherein the first and second vertical. Hall elements are configured to generate first and second vertical Hall element output signals, respectively, wherein the first vertical Hall element output signal has a first external magnetic field component responsive to the external magnetic field and a first offset component, and wherein the second vertical Hall element output signal has a second external magnetic field component responsive to the external magnetic field and a second offset component;

combining the first and second vertical Hall element output signals so that the first and second magnetic field components add constructively to generate a constructive signal;

providing a first one or more current signals to a first selected one or more contacts of the first selected set of contacts, wherein the first one or more current signals flow into or out of a central contact of the first selected set of contacts;

providing a second one or more current signals to a second selected one or more contacts of the second selected set of contacts, wherein the second one or more current signals flow into or out of a contact proximate to a central contact of the second selected set of contacts, wherein the first and second one or more contacts of the first and second vertical Hall elements are representative of first and second different coupling phases, respectively; and

sequencing around the plurality of vertical Hall elements, sequentially selecting the first and second vertical Hall elements as different ones of the plurality of vertical Hall elements in order to generate a constructive sequenced signal.

21. The method of claim 20, wherein the plurality of contacts are disposed over a common implant and diffusion region in the substrate forming a circular vertical Hall (CVH) sensing element.

22. The method of claim 21, further comprising:

selecting third and fourth vertical Hall elements from among the plurality of vertical Hall elements, the third vertical Hall element having a third selected set of contacts selected from among the plurality of sets of contacts and the fourth vertical Hall element having a fourth selected set of contacts selected from among the plurality of sets of contacts, wherein the third and fourth vertical Hall elements are configured to generate third and fourth vertical Hall element output signals, respectively, wherein the third vertical Hall element output signal has a third external magnetic field component responsive to the external magnetic field and a third offset component, and wherein the fourth vertical Hall element output signal has a fourth external magnetic field component responsive to the external magnetic field and a fourth offset component; and

combining the third and fourth vertical Hall element output signals together to generate a compensating signal.

23. The method claim 22, wherein the combining the third and fourth vertical Hall element output signals results in the third and fourth external magnetic field components adding destructively.

24. The method of claim 22, wherein the combining the third and fourth vertical Hall element output signals results in the third and fourth external magnetic field components adding constructively.

25. The method of claim 22, further comprising:

providing a third one or more current signals to a third selected one or more contacts of the third selected set of contacts;

providing a fourth one or more current signals to a fourth selected one or more contacts of the fourth selected set of contacts;

sequencing around the plurality of vertical Hall elements, sequentially selecting the third and fourth vertical Hall elements as different ones of the plurality of vertical Hall elements in order to generate a compensating sequenced signal; and

combining a first signal representative of the constructive sequenced signal and a second signal representative of the compensating sequenced signal.

26. The method of claim 25, wherein the third one or more current signals flow into or out of a central contact of the third selected set of contacts, and wherein the fourth one or more current signals flow into or out of a central contact of the fourth selected set of contacts, wherein the third and fourth selected one or more contacts of the third and fourth vertical Hall elements are representative of the same coupling phase.

27. The method of claim 25, wherein the third one or more current signals flow into or out of a contact proximate to a central contact of the third selected set of contacts, and wherein the fourth one or more current signals flow into or out of a contact proximate to a central contact of the fourth selected set of contacts.

28. The method of claim 25, wherein the third one or more current signals flow into or out of a contact proximate to a central contact of the third selected set of contacts, and wherein the fourth one or more current signals flow into or out of a central contact of the fourth selected set of contacts, wherein the third and fourth selected one or more contacts of the third and fourth vertical Hall elements are representative of the different coupling phases.

29. The method of claim 25, further comprising:

applying a predetermined phase adjustment to a selected one of the constructive sequenced signal or the compensating sequenced signal to generate a respective one of the first signal or the second signal.

30. The method of claim 25, wherein the first and second vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

31. The method of claim 30, wherein the third and fourth vertical Hall elements are disposed one hundred eighty degrees apart around the circle, wherein a line between centers of the first and second vertical Hall elements and a line between centers of the third and fourth vertical Hall elements are approximately ninety degrees apart.

32. The method of claim 25, wherein the first and second vertical Hall elements are immediately adjacent to each other and the third and fourth vertical Hall elements are immediately adjacent to each other.

33. The method of claim 32, wherein the first and fourth vertical Hall elements are disposed one hundred eighty degrees apart around the circle, and wherein the second and third vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

34. The method of claim 25, wherein the first and fourth vertical Hall elements are disposed one hundred eighty degrees apart around the circle, and wherein the second and third vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

35. The method of claim 21, wherein the first and second vertical Hall elements are disposed one hundred eighty degrees apart around the circle.

36. The method of claim 20, further comprising:

selecting third and fourth vertical Hall elements from among the plurality of vertical Hall elements, the third vertical Hall element having a third selected set of contacts selected from among the plurality of sets of contacts and the fourth vertical Hall element having a fourth selected set of contacts selected from among the plurality of sets of contacts, wherein the third and fourth vertical Hall elements are configured to generate third and fourth vertical Hall element output signals, respectively, wherein the third vertical Hall element output signal has a third external magnetic field component responsive to the external magnetic field and a third offset component, and wherein the fourth vertical Hall element output signal has a fourth external magnetic field component responsive to the external magnetic field and a fourth offset component; and

combining the third and fourth vertical Hall element output signals together to generate a compensating signal.

37. The method of claim 36, further comprising:

providing a third one or more current signals to a third selected one or more contacts of the third selected set of contacts;

providing a fourth one or more current signals to a fourth selected one or more contacts of the fourth selected set of contacts;

sequencing around the plurality of vertical Hall elements, sequentially selecting the third and fourth vertical Hall elements as different ones of the plurality of vertical Hall elements in order to generate a compensating sequenced signal; and

combining a first signal representative of the constructive sequenced signal and a second signal representative of the compensating sequenced signal.

38. The method of claim 37, further comprising:

applying a predetermined phase adjustment to a selected one of the constructive sequenced signal or the compensating sequenced signal to generate a respective one of the first signal or the second signal.