A Monolithic CMOS Hall Switch Sensor System with High Precision and Low Power Consumption

Abstract

A monolithic CMOS Hall switch sensor which consists of a square-shaped Hall plate and a novel signal conditioner is presented. The proposed signal conditioner employs dynamic offset cancellation technique together with spinning current technique to eliminate offset and low frequency 1/f noise, which improves both precision and power consumption of the sensor system. The dynamic offset cancellation circuit uses two capacitors and a pair of MOS switches along with particular timing control, which has a relatively simple structure. This Hall sensor has been integrated with a 0.15µm standard CMOS process. The measurement results show that the sensor system has a residual offset of below 7µV and the equivalent input-referred thermal noise is below 10µV over a temperature range from -40°C to 125°C. The measured power consumption is below 1mA.