Quasi-analytical study of offset voltage due to piezoresistive effect in vertical Hall devices by mapping techniques

This paper presents a novel application of mapping techniques to assess the effect of piezoresistance on the offset voltage of vertical Hall sensors. The quasi-analytical method consists first of an "isotropization\´\´ step performed by an affine transformation, followed by a more common series of conformal mappings. A detailed analysis of the mapping steps shows that sensors having all their contacts along a straight line will not exhibit any offset voltage due to piezoresistive effects if the sensor boundaries are placed far enough from the central contacts. In particular, the offset can be very efficiently reduced in 5-contact devices just by moving their vertical boundaries.