DC low current Hall effect measurements

Abstract

A lot of electronic devices utilize linear Hall sensors to measure current and the magnetic field, as well as to perform switching and latching operations. Smartphones, laptops, and ereaders all work with very low (sub-milliampere) currents. To perform a switching function in low-power devices, however, Hall sensors must work in the microampere regime. In this work we demonstrate, for the first time, the ability of a standard Hall detector to work linearly in the microampere regime between 0 and 0.7 Tesla. To do so, we developed a current source with RMS noise on the order of 10–100 pA/sqrt(Hz). An optimized electronic circuit with minimal connections feeds current to the Hall sensor, and the Hall voltage is measured within industrial nanovoltmeter. We demonstrate the capabilities of this system by precisely measuring the slope of the Hall effect with a four-point probe at current intensities of 100, 10, and 1 microA. We expect that our system can work as a microampere Hall sensor using external voltage detectors.