Circuits and methods for processing signals generated by a circular vertical hall (CVH) sensing element in the presence of a multi-pole magnet

Patent metadata

Field	Value
Publication number	US-9541424-B2
Application number	US-201615186433-A
Country	US
Kind code	B2
Filing date	Jun 18, 2016
Priority date	Dec 21, 2012
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

Described embodiments provide a magnetic field sensor has a circular vertical Hall (CVH) sensing element with a plurality of vertical Hall elements disposed over a common implant region in a substrate. The magnetic field sensor generates output signals responsive to a magnetic field generated by a multi-pole magnet having a plurality of north poles and also a plurality of south poles. An angle sensor generates an angle signal representative of an angle of a direction component of the magnetic field. A pole pair counter generates a count signal representative of a count of a number of the pole pairs of the multi-pole magnet that move past the CVH sensing element. An angle interpolation module generates a reconstructed angle signal representative of an angular position of the multi-pole magnet relative to the CVH sensing element based upon the count signal and the angle signal. Corresponding methods are also described.

First claim

What is claimed is:

1. A magnetic field sensor, comprising:
a semiconductor substrate having a first surface in a coordinate plane;
a Circular Vertical Hall (CVH) sensing element comprised of a plurality of vertical Hall elements, wherein each one of the plurality of vertical Hall elements is arranged upon a common circular implant region in the first surface of the semiconductor substrate, wherein the plurality of vertical Hall elements is configured to generate a plurality of output signals responsive to a magnetic field having a direction component, wherein the CVH sensing element is configured to generate a CVH output signal comprised of the plurality of output signals, wherein the magnetic field results from a multi-pole magnet disposed proximate to the magnetic field sensor and having a plurality of north poles and a plurality of south poles, each north pole proximate to at least one south pole;
an angle sensing circuit coupled to receive the CVH output signal and configured to generate an angle signal representative of an angle of the direction component of the magnetic field as the multi-pole magnet and the CVH sensing element move relative to each other;
a pole pair counting module coupled to receive a signal representative of the angle signal and configured to generate a count signal representative of a count of a number of the pole pairs of the multi-pole magnet that move past the CVH sensing element; and
an angle interpolation module coupled to receive the angle signal and the count signal, the angle interpolation module configured to generate a reconstructed angle signal representative of an angular position of the multi-pole magnet relative to the CVH sensing element, the reconstructed angle signal generated based upon the count signal and the angle signal, the reconstructed angle signal having a higher resolution than the angle signal.

2. The magnetic field sensor of claim 1 , wherein the multi-pole magnet comprises a multi-pole ring magnet, and wherein the plurality of north poles and a plurality of south poles are disposed in the coordinate plane.

3. The magnetic field sensor of claim 2 , wherein the ring magnet is movably disposed to rotate about an axis perpendicular to the coordinate plane.

4. The magnetic field sensor of claim 1 , wherein the multi-pole magnet comprises a multi-pole line magnet, and wherein the plurality of north poles and a plurality of south poles are disposed in the coordinate plane.

5. The magnetic field sensor of claim 4 , wherein the line magnet is movably disposed to move along a line in the coordinate plane.

6. The magnetic field sensor of claim 4 , wherein the CVH sensing element is movably disposed to move along a line in the coordinate plane.

7. The magnetic field sensor of claim 1 , wherein the reconstructed angle signal removes an ambiguity from the angle signal of the angular position of the multi-pole magnet relative to the CVH sensing element.

8. The magnetic field sensor of claim 1 , wherein the interpolated signal provides a first resolution of the position of the multi-pole magnet relative to the CVH sensing element, wherein the magnetic field sensor further comprises:
a magnetic field sensing element configured to generate a magnetic field sensing element output signal responsive to a magnetic field generated by a second multi-pole magnet having at least one north pole and at least one south pole;
an electronic circuit coupled to receive the magnetic field sensing element output signal and configured to generate a position signal, wherein the position signal is representative of the position of the second multi-pole magnet relative to the magnetic field sensing element with a second different resolution; and
an output protocol module coupled to receive the interpolated signal and the position signal, and configured to generate an output signal representative of the position signal at some times and configured to generate the output signal representative of the interpolated signal at other times.

9. A method of position sensing, comprising:
generating, with a Circular Vertical Hall (CVH) sensing element, a plurality of output signals responsive to a magnetic field having a direction component parallel to a coordinate plane, wherein the CVH sensing element is configured to generate a CVH output signal comprised of the plurality of output signals, wherein the magnetic field result from a multi-pole magnet having a plurality of north poles and a plurality of south poles, each north pole proximate to at least one south pole;
generating a CVH output signal comprised of the plurality of output signals;
generating an angle signal representative of an angle of the direction component of the magnetic field as the multi-pole magnet and the CVH sensing element move relative to each other;
generating a pole pair count signal representative of a count of a number of the pole pairs of the multi-pole magnet that moves past the CVH sensing element; and
generating a reconstructed angle signal representative of an angular position of the multi-pole magnet relative to the CVH sensing element, the reconstructed angle signal generated based upon the pole pair count signal and the angle signal, the reconstructed angle signal having a higher resolution than the angle signal.

10. The method of claim 9 , wherein the multi-pole magnet comprises a multi-pole ring magnet, and wherein the plurality of north poles and a plurality of south poles are disposed in the coordinate plane.

11. The method of claim 10 , wherein the ring magnet is movably disposed to rotate about an axis perpendicular to the coordinate plane.

12. The method of claim 10 , wherein the multi-pole magnet comprises a multi-pole line magnet, and wherein the plurality of north poles and a plurality of south poles are disposed in the coordinate plane.

13. The method of claim 12 , wherein the line magnet is movably disposed to move along a line in the coordinate plane.

14. The method of claim 12 , wherein the CVH sensing element is movably disposed to move along a line in the coordinate plane.

15. The method of claim 9 , wherein generating the reconstructed angle signal comprises removing an ambiguity from the angle signal of the angular position of the multi-pole magnet relative to the CVH sensing element.

16. The method claim 9 , wherein the interpolated signal provides a first resolution of the position of the multi-pole magnet relative to the CVH sensing element, wherein the method further comprises:
generating a magnetic field sensing element output signal responsive to a magnetic field generated by a second multi-pole magnet having at least one north pole and at least one south pole;
generating a position signal is representative of the position of the second multi-pole magnet relative to the magnetic field sensing element with a second different resolution; and
generating an output signal representative of the position signal at some times and generating the output signal representative of the interpolated signal at other times.

17. A magnetic field sensor, comprising:
a Circular Vertical Hall (CVH) sensing element comprised of a plurality of vertical Hall elements, wherein each one of the plurality of vertical Hall elements is arranged upon a common circular implant region in a first surface of a semiconductor substrate, wherein the plurality of vertical Hall elements is configured to generate a plurality of output signals responsive to a magnetic field having a direction component, wherein the CVH sensing element is configured to generate a CVH output signal comprised of

Assignees

• Allegro Microsystems Llc

Inventors

• Friedrich Andreas P
• Foletto Andrea

Classifications

• G01D5/2451

  Incremental encoders (G01D5/2454 takes precedence) · CPC title

• G01D5/145 Primary

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title

• G01R33/072

  Constructional adaptation of the sensor to specific applications · CPC title

• G01R33/007

  Environmental aspects, e.g. temperature variations, radiation, stray fields (G01R33/025 takes precedence) · CPC title

• G01R33/0023

  Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration (G01R33/0017 takes precedence) · CPC title