A new approach to offset reduction in sensors: the sensitivity-variation method

A new approach to offset reduction in solid-state sensors is presented. The method is based on the application of a signal to a third port of a sensor. When the sensor has the property that the sensitivity and the offset have different responses to the third-port signal, a large reduction in the effective offset can be obtained. The method is employed on a magnetic-field-sensitive dual-collector magnetotransistor and a Hall element. It appears that the method is very successful in reducing the offset of the magnetotransistor, whereas that of the Hall element is not affected at all. This is in agreement with the analysis of the method presented.