A p-n junction temperature sensor with switched current excitation

A temperature sensor based on the use of two forward-biased p-n junctions is known to exhibit good linearity. An alternative sensor configuration, based on the same principle, but employing only one p-n junction is presented. The forward current through the p-n junction is switched alternately between two fixed values and the difference between the corresponding voltages is shown to vary linearly with temperature. This scheme eliminates the problems associated with close matching required for the two p-n junctions. Experimental results obtained with the proposed scheme in two circuit configurations with two different sensors are presented. The temperature dependence of the incremental resistance of a p-n junction was experimentally verified for building an alternative temperature sensor