Magnetic field sensor circuit
First Claim
1. A magnetic field sensor circuit comprising:
- a first magneto-resistive sensor for sensing a first magnetic field component in a first direction to supply a first sense signal,a first flipping coil for applying a first flipping magnetic field with a periodically changing polarity to the first magneto-resistive sensor for causing the first sense signal to have alternating different levels synchronized with the first flipping magnetic field,a second magneto-resistive sensor for sensing a second magnetic field component in a second direction different than the first direction to supply a second sense signal,a second flipping coil for applying a second flipping magnetic field with a periodically changing polarity to the second magneto-resistive sensor for causing the second sense signal to have an alternating different levels synchronized with the second flipping magnetic field, a phase of the first flipping magnetic field and the second flipping magnetic field being different,a differential amplifier configured to receive the first sense signal and the second sense signal to obtain a difference signal,a first synchronous demodulator configured to receive the difference signal and a first switching signal being phase locked to the alternating different levels of the first sense signal to supply a first output signal indicating the first magnetic field component, anda second synchronous demodulator configured to receive the difference signal and a second switching signal being phase locked to the alternating different levels of the second sense signal to supply a second output signal indicating the second magnetic field component.
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Abstract
A magnetic field sensor circuit comprises a first magneto-resistive sensor (Rx) which senses a first magnetic field component in a first direction to supply a first sense signal (Vx). A first flipping coil (FC1) applies a first flipping magnetic field with a periodically changing polarity to the first magneto-resistive sensor (Rx) to cause the first sense signal (Vx) to have alternating different levels synchronized with the first flipping magnetic field. A second magneto -resistive sensor (Ry) senses a second magnetic field component in a second direction different than the first direction to supply a second sense signal (Vy). A second flipping coil (FC2) applies a second flipping magnetic field with a periodically changing polarity to the second magneto -resistive sensor (Ry) to cause the second sense signal (Vy) to have an alternating different levels synchronized with the second flipping magnetic field. The first flipping magnetic field and the second flipping magnetic field have a phase shift. A differential amplifier (AMP1) receives the first sense signal (Vx) and the second sense signal (Vy) to obtain a difference signal (Vd). A first synchronous demodulator (DEM1) receives the difference signal (Vd) and a first switching signal (Q1) being phase locked to the alternating different levels of the first sense signal (Vx) to supply a first output signal (Vox) indicating the first magnetic field component. A second synchronous demodulator (DEM2) receives the difference signal (Vd) and a second switching signal (Q2) being phase locked to the alternating different levels of the second sense signal (Vy) to supply a second output signal (Voy) indicating the second magnetic field component.
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Citations
11 Claims
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1. A magnetic field sensor circuit comprising:
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a first magneto-resistive sensor for sensing a first magnetic field component in a first direction to supply a first sense signal, a first flipping coil for applying a first flipping magnetic field with a periodically changing polarity to the first magneto-resistive sensor for causing the first sense signal to have alternating different levels synchronized with the first flipping magnetic field, a second magneto-resistive sensor for sensing a second magnetic field component in a second direction different than the first direction to supply a second sense signal, a second flipping coil for applying a second flipping magnetic field with a periodically changing polarity to the second magneto-resistive sensor for causing the second sense signal to have an alternating different levels synchronized with the second flipping magnetic field, a phase of the first flipping magnetic field and the second flipping magnetic field being different, a differential amplifier configured to receive the first sense signal and the second sense signal to obtain a difference signal, a first synchronous demodulator configured to receive the difference signal and a first switching signal being phase locked to the alternating different levels of the first sense signal to supply a first output signal indicating the first magnetic field component, and a second synchronous demodulator configured to receive the difference signal and a second switching signal being phase locked to the alternating different levels of the second sense signal to supply a second output signal indicating the second magnetic field component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification