Circuits and Methods for Self-Calibrating or Self-Testing a Magnetic Field Sensor Using Phase Discrimination

摘要

A magnetic field sensor has a reference magnetic field channel and an external magnetic field channel. The magnetic field sensor uses phase discrimination to isolate a reference-magnetic-field signal component from an external magnetic field signal component in the two channels.

主权项

1. A magnetic field sensor, comprising:
a reference magnetic field generator, wherein the reference magnetic field generator is configured to generate an AC reference magnetic field having a first frequency with a first phase; a magnetic field sensing circuit comprising at least one magnetic field sensing element, wherein the magnetic field sensing circuit is configured to generate a combined output signal responsive to the AC reference magnetic field and also responsive to an external magnetic field; and a signal processing circuit coupled to receive the combined output signal, wherein the signal processing circuit comprises a first modulator, wherein the first modulator is configured to modulate the combined signal with the same first frequency as the reference magnetic field generator but with a second different phase to generate a modulated combined signal.