Gain equalization for multiple axis magnetic field sensing
First Claim
Patent Images
1. A magnetic field sensor comprising:
- a plurality of magnetic field sensing elements including;
a first magnetic field sensing element arranged to have a maximum response to an external magnetic field and a reference magnetic field along a first axis and having an output that provides a first signal representing the magnetic fields as detected by the first magnetic field sensing element; and
a second magnetic field sensing element arranged to have a maximum response to the external magnetic field and the reference magnetic field along a second axis and having an output that provides a second signal representing the magnetic field as detected by the second magnetic field sensing element;
a coil structure configured to generate the reference magnetic field when a current passes through the coil structure;
a memory containing at least one reference gain value comprising a relative gain between the first and second magnetic field sensing elements;
a gain equalization circuit coupled to receive the first signal and the second signal and configured to;
extract a first reference portion of the first signal representing the reference field;
extract a second reference portion of the second signal representing the reference field;
measure a first gain of the first reference portion;
measure a second gain of the second reference portion;
compare the first gain to the at least one reference gain;
compare the second gain to the at least one reference gain;
adjust the first gain based on the comparison of the first gain and the reference gain value so that the first gain is normalized to an expected value; and
adjust the second gain based on the comparison of the second gain and the reference gain value so that the second gain is normalized to the expected value.
6 Assignments
0 Petitions
Accused Products
Abstract
A magnetic field sensor for sensing external magnetic fields on multiple axes comprises a coil structure and a gain equalization circuit. The coil structure generates reference fields on magnetic field sensing elements in each axis. The gain equalization circuit measures and compares reference fields to generate gain-equalized output signals responsive to the external magnetic fields.
71 Citations
19 Claims
-
1. A magnetic field sensor comprising:
-
a plurality of magnetic field sensing elements including; a first magnetic field sensing element arranged to have a maximum response to an external magnetic field and a reference magnetic field along a first axis and having an output that provides a first signal representing the magnetic fields as detected by the first magnetic field sensing element; and a second magnetic field sensing element arranged to have a maximum response to the external magnetic field and the reference magnetic field along a second axis and having an output that provides a second signal representing the magnetic field as detected by the second magnetic field sensing element; a coil structure configured to generate the reference magnetic field when a current passes through the coil structure; a memory containing at least one reference gain value comprising a relative gain between the first and second magnetic field sensing elements; a gain equalization circuit coupled to receive the first signal and the second signal and configured to; extract a first reference portion of the first signal representing the reference field; extract a second reference portion of the second signal representing the reference field; measure a first gain of the first reference portion; measure a second gain of the second reference portion; compare the first gain to the at least one reference gain; compare the second gain to the at least one reference gain; adjust the first gain based on the comparison of the first gain and the reference gain value so that the first gain is normalized to an expected value; and adjust the second gain based on the comparison of the second gain and the reference gain value so that the second gain is normalized to the expected value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
Specification