D. Nikolov

Amperometric circuit for high accuracy 2D and 3D magnetic-field measurements

A novel amperometric measuring circuit for reducing the channel cross-sensitivity and the experimental verification of its applicability in high accuracy 2D and 3D silicon magnetic-field microdevices are presented. The investigation carried out shows that the most crucial role in the cross-sensitivity phenomenon, especially in the multidimensional Hall sensors, is the lateral parasitic conductance, which gives the main component in this drawback. The novelty of the used metrological approach, which drastically improves the accuracy, is related to keeping constant voltage conditions on the chip surface contacts with and without magnetic field. The used circuit is characterized by high stability in a wide interval of change of the supply current and in a large range of magnetic inductions up to 1 T. Testing the 3D silicon magnetometer samples, about 45% reduction of the channel cross-sensitivity is achieved, which is a very promising result. The new amperometric circuit is an integrated solution and together with the multidimensional sensor represents a one-chip microsystem with universal applicability.

A New Highly Sensitive Parallel — Field Hall Microsensor

A new parallel-field silicon Hall microsensor with dramatically improved magnetosensitivity is investigated experimentally. For the first time this result is achieved by an electrical variation both of the geometrical correction factor and the thickness in the magnetic-field direction of the device. The operating principle involves the controlling of the curvilinear majority current trajectory using unexpectedly a minority carrier injection without reducing the Hall coefficient. With an injection of only 10 µA an increasing of the output voltage of over 50 % is reached.