Pn Junction Temperature-Sensor by Use of Superimposed AC Signal
Noriaki Takashima, Mitsuteru Kimura · IEEJ Transactions on Sensors and Micromachines · 2007
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.