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US 8,680,846 B2Granted
Circuits and methods for self-calibrating or self-testing a magnetic field sensor
AssigneeAllegro MicroSystems, LLC
InventorsJuan Manuel Cesaretti, Gerardo Monreal
Life of this patent
Estimating the term…
Abstract
A magnetic field sensor includes a reference-field-sensing circuit channel that allows a calibration or a self-test of the circuitry of the magnetic field sensor. The magnetic field sensor can generate a reference magnetic field to which the magnetic field sensor is responsive.
Claims62
A magnetic field sensor, comprising:
- at least two magnetic field sensing elements;
- a first switching circuit coupled to the at least two magnetic field sensing elements, wherein the first switching circuit is configured to couple the at least two magnetic field sensing elements into a measured-field-sensing configuration and into a reference-field-sensing configuration, wherein the first switching circuit is configured to couple the at least two magnetic field sensing elements in parallel so as to respond in cooperation in the presence of an external magnetic field when coupled in the measured-field-sensing configuration, and to couple the at least two magnetic field sensing elements such that the responses to the external magnetic field oppose one another when coupled in the reference-field-sensing configuration, and wherein the first switching circuit is operable to switch back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the first switching circuit is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to the external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration;
- a processing circuit coupled to receive the magnetic field signal;
- and
- a feedback circuit coupled to receive a signal representative of the magnetic field signal from the processing circuit and configured to generate a feedback signal to control at least one of a bias signal applied to drive the at least two magnetic field sensing elements or a gain of the processing circuit.
5 more elements
A method of generating a calibration or a self-test of a magnetic field sensor, comprising:
- coupling at least two magnetic field sensing elements into a measured-field-sensing configuration, wherein the coupling the at least two magnetic field sensing elements into the measured-field-sensing comprises coupling the at least two magnetic field sensing elements in parallel so as to respond in cooperation in the presence of an external field,
- coupling the at least two magnetic field sensing elements into a reference-field-sensing configuration, wherein the coupling that at least two magnetic field sensing elements into the reference-field-sensing configuration comprises coupling the at least two magnetic field sensing elements such that their responses to the external magnetic field oppose one another,
- switching back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the switching is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to the external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration;
- and
- using a signal representative of the magnetic field signal as feedback signal to control at least one of a bias signal applied to drive that at least two magnetic field sensing elements or a gain of a processing circuit coupled to the at least two magnetic field sensing elements.
5 more elements
A magnetic field sensor, comprising:
- at least two magnetic field sensing elements;
- and
- a first switching circuit coupled to the at least two magnetic field sensing elements, wherein the first switching circuit is configured to couple the at least two magnetic field sensing elements into a measured-field-sensing configuration and into a reference-field-sensing configuration, wherein the first switching circuit is operable to switch back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the first switching circuit is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to an external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration, wherein the reference magnetic field comprises first and second reference magnetic fields pointing in opposite directions at locations of selected ones of the at least two magnetic field sensing elements, wherein the magnetic field sensor further comprises:
- a magnetic field generator operable to generate the first and second reference magnetic fields, wherein the magnetic field generator comprises:
- at least two reference field conductor portions proximate to the at least two magnetic field sensing elements, respectively, wherein the at least two reference field conductor portions are configured to carry a reference current to generate the reference magnetic field, wherein the reference magnetic field comprises at least two reference magnetic field portions having respective magnetic field directions directed in opposite directions, wherein the magnetic field sensor further comprises:
- a second switching circuit coupled to provide the reference current, wherein the second switching circuit is operable to alternately switch the reference current between a first reference current direction and a second opposite reference current direction synchronously with the first switching rate.
6 more elements
A magnetic field sensor, comprising:
- at least two magnetic field sensing elements;
- and
- a first switching circuit coupled to the at least two magnetic field sensing elements, wherein the first switching circuit is configured to couple the at least two magnetic field sensing elements into a measured-field-sensing configuration and into a reference-field-sensing configuration, wherein the first switching circuit is operable to switch back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the first switching circuit is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to an external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration, wherein the reference magnetic field comprises first and second reference magnetic fields pointing in opposite directions at locations of selected ones of the at least two magnetic field sensing elements, wherein the magnetic field sensor further comprises:
- a magnetic field generator operable to generate the first and second reference magnetic fields, wherein the magnetic field generator comprises:
- at least two reference field conductor portions proximate to the at least two magnetic field sensing elements, respectively, wherein the at least two reference field conductor portions are configured to carry a reference current to generate the reference magnetic field, wherein the reference magnetic field comprises at least two reference magnetic field portions having respective magnetic field directions directed in opposite directions, wherein the magnetic field sensor further comprises:
- a processing circuit coupled to receive the magnetic field signal from the first switching circuit, wherein the magnetic field signal, during first time periods, is representative of the measured-magnetic-field-responsive signal portion and, during second different time periods interleaved with the first time periods at a rate synchronous with the first switching rate, is representative of the reference-magnetic-field-responsive signal portion, wherein the processing circuit comprises:
- a first processing channel time multiplexed to select and to process the signal representative of the measured-magnetic-field-responsive signal portion during the first time periods to generate a first sensor output signal representative of the measured-magnetic-field-responsive signal portion;
- and
- a second different processing channel time multiplexed to select and to process the signal representative of the reference-magnetic-field-responsive signal portion during the second different time periods to generate a second different sensor output signal representative of the reference-magnetic-field-responsive signal portion.
9 more elements
A method of generating a calibration or a self-test of a magnetic field sensor, comprising:
- coupling at least two magnetic field sensing elements into a measured-field-sensing configuration,
- coupling the at least two magnetic field sensing elements into a reference-field-sensing configuration, and
- switching back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the switching is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to an external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration, wherein the method further comprises:
- generating a reference current to generate the reference magnetic field, wherein the reference magnetic field comprises at least two reference magnetic field portions having respective magnetic field directions directed in opposite directions;
- and
- switching alternately between a first reference current direction and a second opposite reference current direction synchronously with the first switching rate.
6 more elements
A method of generating a calibration or a self-test of a magnetic field sensor, comprising:
- coupling at least two magnetic field sensing elements into a measured-field-sensing configuration,
- coupling the at least two magnetic field sensing elements into a reference-field-sensing configuration, and
- switching back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the switching is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to an external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration, wherein the method further comprises;
- generating a reference current to generate the reference magnetic field, wherein the reference magnetic field comprises at least two reference magnetic field portions having respective magnetic field directions directed in opposite directions;
- receiving the magnetic field signal from the first switching circuit, wherein the magnetic field signal, during first time periods, is representative of the measured-magnetic-field-responsive signal portion and, during second different time periods interleaved with the first time periods at a rate synchronous with the first switching rate, is representative of the reference-magnetic-field-responsive signal portion;
- time multiplexing to select and to process the signal representative of the measured-magnetic-field-responsive signal portion during the first time periods to generate a first sensor output signal representative of the measured-magnetic-field-responsive signal portion;
- and
- time multiplexing to select and to process the signal representative of the reference-magnetic-field-responsive signal portion during the second different time periods to generate a second different sensor output signal representative of the reference-magnetic-field-responsive signal portion.
8 more elements
A magnetic field sensor, comprising:
- at least two magnetic field sensing elements;
- a first switching circuit coupled to the at least two magnetic field sensing elements, wherein the first switching circuit is configured to couple the at least two magnetic field sensing elements into a measured-field-sensing configuration and into a reference-field-sensing configuration, wherein the first switching circuit is operable to switch back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the first switching circuit is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to an external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration, wherein the reference magnetic field comprises first and second reference magnetic fields pointing in opposite directions at locations of selected ones of the at least two magnetic field sensing elements;
- a processing circuit coupled to receive the magnetic field signal;
- a feedback circuit coupled to receive a signal representative of the magnetic field signal from the processing circuit and configured to generate a feedback signal to control at least one of a bias signal applied to drive the at least two magnetic field sensing elements or a gain of the processing circuit;
- and
- a magnetic field generator operable to generate the first and second reference magnetic fields.
6 more elements
A method of generating a calibration or a self-test of a magnetic field sensor, comprising:
- coupling at least two magnetic field sensing elements into a measured-field-sensing configuration,
- coupling the at least two magnetic field sensing elements into a reference-field-sensing configuration,
- switching back and forth alternately between the measured-field-sensing configuration and the reference-field-sensing configuration at a first switching rate to provide a magnetic field signal, wherein the switching is configured to generate the magnetic field signal comprising:
- a measured-magnetic-field-responsive signal portion responsive to an external magnetic field when coupled in the measured-field-sensing configuration;
- and
- a reference-magnetic-field-responsive signal portion responsive to a reference magnetic field when coupled in the reference-field-sensing configuration, wherein the reference magnetic field comprises first and second reference magnetic fields pointing in opposite directions at locations of selected ones of the at least two magnetic field sensing elements;
- and
- using a signal representative of the magnetic field signal as feedback signal to control at least one of a bias signal applied to drive the at least two magnetic field sensing elements or a gain of a processing circuit coupled to the at least two magnetic field sensing elements.
5 more elements
Dependencies are inferred from the claim text.