A Compact CMOS 3-D Magnetic Field Sensor

Abstract

A ring-shape vertical hall device for X- and Y-direction, and a split-drain horizontal hall device for Z-direction are combined to implement the 3-D sensor. This merged design has the advantage of less area and lower power consumption. The sensitivities of vertical hall device (ring-shape magneto-resistor) and horizontal hall device (split-drain MAGFET) are estimated to be 0.11V/T and 2.88V/T respectively. Z-direction demonstrates a higher sensitivity. A high gain cascade differential amplifier is integrated with the sensor to further amplify the signal.