Magnetic field sensors and sensing circuits

摘要

A circuit for sensing an external magnetic field includes first voltage source, first magnetic sensor, second magnetic sensor, bias voltage unit, clamp voltage current mirror unit, signal transfer amplifying unit. The first voltage source provides a power voltage. The first magnetic sensor provides a reference current. The second magnetic sensor senses an external magnetic field and the conductivity of the second magnetic sensor varies in response to the external magnetic field. The bias voltage unit connected to the first magnetic sensor and the second magnetic sensor provides a bias voltage to the first magnetic sensor and the second magnetic sensor. The clamp voltage current mirror unit generates a reference current for the first magnetic sensor and mirrors the reference current to the second magnetic sensor. The signal transfer amplifying unit generates an output voltage and an additional current to compensate the change in the conductivity of the second magnetic sensor.

主权项

1. A circuit for sensing an external magnetic field, comprising:
a first voltage source for providing a power voltage; a first magnetic sensor for providing a reference current; a first conductive wire over the first magnetic sensor, to apply a set current and thereby set the first magnetic sensor to a reference state during a sensing period for the external magnetic field, wherein the external magnetic field is also applied to the first magnetic sensor; a second magnetic sensor for sensing the external magnetic field in the sensing period, a conductivity of the second magnetic sensor varying in response to the external magnetic field; a second conductive wire over the second magnetic sensor, to reset the second magnetic sensor before entering the sensing period; a bias voltage unit connected to the first magnetic sensor and the second magnetic sensor for providing a bias voltage to the first magnetic sensor and the second magnetic sensor; a clamp voltage current mirror unit for generating the reference current for the first magnetic sensor and mirroring the reference current to the second magnetic sensor; and a signal transfer amplifying unit for generating an output voltage and an additional current to compensate the change in the conductivity of the second magnetic sensor.