Patent ID: 7818890
Filing Date: 2010-10-26
Classification: B82Y,G01R

Abstract:
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, 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.