Double-Hall sensor with self-compensated offset

A novel Double-Hall sensor is reported with a signal offset compensated by design. It consists of two single Hall devices sharing the same active area. The sensor detects the magnetic induction perpendicular to the chip surface. The sensor signal is given by the difference of the Hall voltages of the two single devices. They have almost equal offsets but magnetic responses of opposite sign due to structure symmetry. This simple self-compensation efficiently reduces the offset to values below 2 mT at room temperature. The thermal offset drift is lower than 11 /spl mu/T//spl deg/C. The small-sized Double-Hall sensor requires only one voltage source and one differential amplifier for operation. Therefore, the implementation of an accurate and inexpensive magnetic sensor microsystem with high cutoff frequency is straightforward.