Limits of offset cancellation by the principle of spinning current Hall probe

An equivalent circuit model for Hall plates with 90° symmetry - as are used in todays smart sensors using the principle of spinning current Hall probe - is derived. It becomes apparent that the commonly used H-bridge 4-resistor type equivalent circuit has to be completed by 2 resistors between the contacts of each diagonal. By use of this equivalent circuit, it is shown that the principle of the spinning current Hall probe works perfectly only for electrically linear probes supplied by a current source. In this case, two orthogonal current directions are enough to cancel the offset. Yet, in the case of voltage biased Hall probes, the offset is not completely eliminated. In practice, integrated Hall probes exhibit electrical nonlinearity due to the depletion layer to the substrate. Monte Carlo simulations show that this nonlinearity limits the performance of offset reduction to roughly 100 nT.