Low field Hall effect magnetometry

Abstract

Low field Hall effect magnetometry has been limited by the performance of the offset (misalignment) voltage rejection technique used. In this work a method is employed where the offset voltage is eliminated without the need to know its exact value nor to make any calibration. To obtain long term stability a new idea is introduced whereby information present in the self field voltage is used to monitor the instrument calibration. These two techniques do not impose any particular requirements on Hall device performance. It is shown that the limiting parameters to the instrument sensitivity are the input bias current and the common mode rejection capability of the voltage sensing differential amplifier. The smallest Hall voltage that was detected was 500 nV, the equivalent of 4 μT field with the device used and no magnetic concentrator arrangement.