Magnetic field sensor and related techniques that provide an angle error correction module

Patent metadata

Field	Value
Publication number	US-9389060-B2
Application number	US-201313766327-A
Country	US
Kind code	B2
Filing date	Feb 13, 2013
Priority date	Feb 13, 2013
Publication date	Jul 12, 2016
Grant date	Jul 12, 2016

Abstract

A magnetic field sensor can include a plurality of magnetic field sensing elements; an angle processing circuit to generate an uncorrected x-y angle value representative of an angle of a magnetic field in an x-y plane, the uncorrected x-y angle value comprising a first angle error component; an angle error correction module to generate an x-y angle error value indicative of an error in the uncorrected x-y angle value, wherein the angle error correction module uses a sinusoidal error relationship, a sine look up table, and a coefficient table memory to determine the x-y angle error value; and a combining module to combine the uncorrected x-y angle value with the x-y angle error value. A similar method is used.

First claim

What is claimed is:

1. A magnetic field sensor, comprising:
a plurality of magnetic field sensing elements, wherein each one of the plurality of magnetic field sensing elements is configured to generate a respective x-y output signal responsive to a magnetic field in an x-y plane;
an angle processing circuit coupled to receive the x-y output signals and configured to generate an uncorrected x-y angle value representative of an angle of the magnetic field in an x-y plane, wherein the uncorrected x-y angle value comprises a first angle error component; and
an angle error correction module coupled to the angle processing circuit and configured to generate an x-y angle error value indicative of an error in the uncorrected x-y angle value, wherein the angle error correction module comprises an algorithm module configured to use a sinusoidal error relationship to describe the first angel error component, sinusoidal with respect to the angle of the magnetic field;
a sine look up table coupled to the angle error correction module and configured to store a plurality of sine values;
a coefficient table memory coupled to the angle error correction module and configured to store a plurality of correction coefficients representative of amplitudes and phases of the sinusoidal error relationship, wherein the angle error correction module is further configured to use a selected one of the plurality of sine values and selected ones of the plurality of correction coefficients in the sinusoidal error relationship to determine the x-y angle error value; and
a combining module configured to combine the uncorrected x-y angle value with the x-y angle error value to generate a corrected x-y angle value having a second angle error component smaller than the first angle error component.

2. The magnetic field sensor of claim 1 ,
wherein the plurality of correction coefficients is associated with respective boundaries of a plurality of temperature segments, each temperature segment bounded by a pair of temperatures; and
a temperature sensor configured to generate a temperature signal representative of a temperature; wherein the angle error correction module comprises:
a segment identification module coupled to receive a temperature value representative of the temperature signal and configured to identify a temperature segment in which the temperature value falls; and
an interpolation module coupled to receive a plurality of the correction coefficients associated with the identified temperature segment, coupled to receive the temperature value, and configured to interpolate between pairs of the correction coefficients in accordance with the temperature value to generate a plurality of interpolated correction coefficients,
wherein the algorithm module is coupled to receive the plurality of interpolated correction coefficients and configured to apply the algorithm using the plurality of interpolated correction coefficients to generate the x-y angle error value.

3. The magnetic field sensor of claim 2 , wherein the plurality of magnetic field sensing elements comprises a plurality of vertical Hall Effect elements arranged as a circular vertical Hall (CVH) element, wherein each one of the plurality of vertical Hall Effect elements is arranged upon a common circular implant and diffusion region in a first major surface of a semiconductor substrate, wherein the plurality of vertical Hall Effect elements is configured to generate a respective plurality of x-y output signals responsive to a magnetic field having a direction component in an x-y plane parallel to the first surface of the semiconductor substrate, the x-y plane having an x-direction and a y-direction orthogonal to the x-direction, wherein the plurality of x-y output signals is generated in a plurality of cycle periods, each cycle period corresponding to one cycle around the CVH sensing element, the cycle periods occurring at a cycle rate.

4. The magnetic field sensor of claim 3 , wherein the selected sine value is selected in accordance with the uncorrected x-y angle value.

5. The magnetic field sensor of claim 3 , wherein the selected sine value is selected in accordance with the x-y angle value and in accordance with an interpolated phase correction coefficient.

6. The magnetic field sensor of claim 3 , wherein the algorithm module is configured to use a temperature-dependent sinusoidal error relationship to describe the first angle error component, sinusoidal with respect to the angle of the magnetic field, and wherein the plurality of correction coefficients comprises:
a plurality of correction coefficients representative of amplitudes and phases of one or more harmonics of the sinusoidal error relationship at a corresponding plurality of different temperatures.

7. The magnetic field sensor of claim 6 , wherein the plurality of correction coefficients further comprises a plurality of correction coefficients representative of amplitudes and phases of first and second harmonics of the sinusoidal error relationship at the corresponding plurality of different temperatures.

8. The magnetic field sensor of claim 6 , wherein the plurality of correction coefficients further comprises a plurality of correction coefficients representative of amplitudes of average angle errors of the sinusoidal error relationship at the corresponding plurality of different temperatures.

9. The magnetic field sensor of claim 6 , further comprising a program control register coupled to receive a program control value, wherein the interpolation module is coupled to receive a value representative of the program control value, and, in response to the program control value, the interpolation module is configured to select the sinusoidal error relationship from among a plurality of sinusoidal error relationships.

10. The magnetic field sensor of claim 3 , further comprising a program control register coupled to receive a program control value, wherein the interpolation module is coupled to receive a value representative of the program control value, and, in response to the program control value, the interpolation module is configured to select an interpolation type from among a plurality of interpolation types.

11. The magnetic field sensor of claim 3 , wherein the interpolation module is configured to generate linear interpolations.

12. The magnetic field sensor of claim 3 , wherein the interpolation module is configured to generate non-linear interpolations.

13. The magnetic field sensor of claim 3 , wherein boundaries of the plurality of temperature segments are unequally spaced in temperature.

14. The magnetic field sensor of claim 3 , further comprising:
a temperature change detection module coupled to the temperature sensor and configured to detect a change in temperature and to generate a temperature change signal indicative of a change in temperature or indicative of no change in temperature, wherein the interpolation module is coupled to the temperature change module and configured to change the plurality of interpolated correction coefficients when the temperature change signal is indicative of a change in temperature and to hold the plurality of interpolated correction coefficients when the temperature change signal is indicative of no change in temperature.

15. The magnetic field sensor of claim 3 , further comprising:
a correction versus rate module coupled to receive a control signal related to the cycle rate and configured to generate a cycle rate correction value in accordance with the cycle rate; and
a second combining module configured to combine the cycle rate correction value with the x-y angle er

Assignees

• Romero Hernan D
• Scheinkerman Ricardo
• Monreal Gerardo A
• Allegro Microsystems Llc

Inventors

• Romero Hernan D
• Scheinkerman Ricardo
• Monreal Gerardo A

Classifications

• G01R33/007

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

• G01R33/077

  Vertical Hall-effect devices · CPC title

• G01B7/023 Primary

  for measuring distance between sensor and object (G01B7/082 and G01B7/102 take precedence) · CPC title

• G01R33/0023 Primary

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

• G01R33/075

  Hall devices configured for spinning current measurements · CPC title