Pn Junction Temperature-Sensor by Use of Superimposed AC Signal

Abstract

A new type absolute temperature-sensor with the measurable temperature range between 77 K and 400 K based on the forward voltage change due to the ambient temperature is proposed and demonstrated. In this temperature-sensor the forward ac voltage change or the forward ac current change at the pn junction diode due to the temperature change is measured for a constant amplitude of superimposed ac small signal of current δI or voltage δV, respectively, on the constant forward dc current I₀. This sensor has merits that it can be calibrated at only one temperature point, that output voltage is proportional to the absolute temperature T and that the measurement can be done independent of the ground point, since the ac signal circuits can be isolated from dc bias voltage circuits.