A Weak Magnetic Field Sensor with InSb-Magnetometers and Lock-in Amplifier

Nowadays, a considerable part of magnetic field sensors is based on the magnetoresistive effect. Those sensors are employed in several automotive and industrial fields, such as current, rotational speed and angular position sensing. In low magnetic field applications, the sensors should fulfill an excellent signal-to-noise ratio and guarantee a high measurement sensitivity. The very first purpose of this work is to select an appropriate semiconductor-based sensor, which is physically compatible to the sensing method. Only sensor materials with high measurement sensitivity are useful. The main contribution of this paper is the combination of a modulated magnetic field with digital filtering methods in order to detect small magnetic fields in a thin Indium antimonide (InSb) Hall plate. Since the sensing principle is based on lock-in architecture, very weak magnetic field magnitudes are detectable. Furthermore, the following concept of a magnetic field sensor is based on signal modulation and digital signal processing to improve the sensing performance.