Back to results
US 8,269,491 B2Granted
DC offset removal for a magnetic field sensor
AssigneeAllegro MicroSystems, LLC
InventorsJohn Cummings, William P. Taylor, David J. Haas
Life of this patent
Estimating the term…
Abstract
Presented is a sensor that includes a magnetoresistive (MR) sensing device to sense a magnetic field and to produce an AC signal voltage proportional to the sensed magnetic field. The sensor also includes circuitry, coupled to the MR sensing device, to remove DC offset from the AC signal voltage. The DC offset may be related to the hysteresis characteristics of the MR sensing device. To remove DC offset, the circuitry may obtain an averaged DC offset and subtract the averaged DC offset from the AC signal voltage to produce a sensor output signal.
Claims8
A sensor, comprising:
- a magnetoresistive (MR) sensing device to sense a magnetic field and to produce an AC signal voltage proportional to the sensed magnetic field;
- circuitry, coupled to the MR sensing device, to receive the AC signal voltage and to remove DC offset from the received AC signal voltage;
- wherein the circuitry comprises a DC offset determiner to determine an averaged DC offset for the AC signal voltage;
- and
- wherein the DC offset determiner includes a positive peak detecting portion to produce a positive peak value, a negative peak detecting portion to produce a negative peak value, a summing block to produce a sum of the positive peak value and the negative peak value and an averaging circuit to divide the sum by two to produce the averaged DC offset.
2 more elements
A sensor, comprising:
- a magnetoresistive (MR) sensing device to sense a magnetic field and to produce an AC signal voltage proportional to the sensed magnetic field;
- circuitry, coupled to the MR sensing device, to receive the AC signal voltage and to remove DC offset from the received AC signal voltage;
- wherein the circuitry comprises a DC offset determiner to determine an averaged DC offset for the AC signal voltage;
- and
- wherein the DC offset determiner further includes a cycle averaging circuit to produce a cycle-averaged DC offset based on the averaged DC offset provided for a predetermined number of clock cycles.
2 more elements
A sensor, comprising:
- a magnetoresistive (MR) sensing device to sense a magnetic field and to produce an AC signal voltage proportional to the sensed magnetic field;
- circuitry, coupled to the MR sensing device, to receive the AC signal voltage and to remove DC offset from the received AC signal voltage;
- wherein the circuitry comprises a DC offset determiner to determine an averaged DC offset for the AC signal voltage;
- and
- wherein the DC offset determiner further includes circuitry to adjust the averaged DC offset so that the AC signal voltage includes a non-zero DC component after the DC offset removal.
2 more elements
A current sensor comprising:
- a conductor to which a current to be measured in applied;
- a MR sensing device, responsive to a magnetic field generated in the conductor when current is applied to the conductor, to produce an AC signal voltage proportional to the current;
- circuitry, coupled to the MR sensing device, to receive the AC signal voltage and to remove DC offset from the received AC signal voltage;
- wherein the circuitry includes a DC offset determiner to determine an averaged DC offset for the AC signal voltage;
- and
- wherein the DC offset determiner includes a positive peak detecting portion to produce a positive peak value, a negative peak detecting portion to produce a negative peak value, a summing block to produce a sum of the positive peak value and a negative peak value and an averaging circuit to divide the sum by two to produce the averaged DC offset.
3 more elements
A method comprising:
- sensing a magnetic field with an MR sensing device and producing an AC signal voltage proportional to the sensed magnetic field;
- removing DC offset from the AC signal voltage;
- wherein removing comprises determining an averaged DC offset for the AC signal voltage;
- and
- wherein determining comprises:
- determining, for a given cycle, a positive peak value and a negative peak value for the AC signal voltage;
- and
- using the positive peak value and the negative peak value to produce the averaged DC offset.
5 more elements
Dependencies are inferred from the claim text.