Spinning-Current Method for Offset Reduction in Silicon Hall Plates

摘要

Research aimed at finding a truly offsetless silicon Hall plate is presented.Only the magnetic field sensitive Hall effect is of interest in Hall plates; all sources of offset, i.e. all other transduction effects, need to be reduced. The offset, which changes with packaging stress in the sensor housing, temperature and time, determines the minimum magnetic field that can be measured, typically 100 mT, without (periodically) calibrating the sensor. The only way to consistently reduce the varying sources of offset is to adaptively compensate them by means of a single sensor. The sources of offset in silicon Hall plates are categorized and the spinning current method is introduced as a novel way of separating the tranduction effects according to their current orientation dependence. An evaluation of the experiments conducted with spinning current Hall plates, with and without electronic circuitry, indicates that all sources of offset can be reduced in a consistent manner, independent of the packaging stress, temperature and time. The low residual offset of less than 100 microT is determined by only those sources of offset, which show the same current orientation independence as the Hall effect, i.e. the Peltier effect and inhomogeneities. On spinning current Hall plates, the offset is a factor of ten or more lower than in currently available orthogonally coupled Hall plates.