CMOS three axis Hall sensor and joystick application

Abstract

We present for the first time a three-axis CMOS Hall sensor based on integrated magnetic concentrator technology (IMC). The sensor measures the two in-plane magnetic field components Bx and By and the vertical component Bz and generates three output voltages proportional to them. The sensing core consists of four Hall elements arranged at 90/spl deg/ under the edge of a ferromagnetic disk (IMC), which is attached to the silicon die. By subtracting the Hall voltages of two opposite Hall elements a voltage proportional to the in-plane components is generated and by adding them a voltage proportional to the perpendicular component. In such a way a planar structure is used to implement a three-axis sensor device. The sensor further contains current sources, dynamic offset compensation and signal amplification and conditioning. The sensor aims for applications where two translatory or rotational movements have to be measured independently and precisely over a large temperature range. Examples are joysticks, car mirror sensors and other control devices.