Abstract
A new method to obtain the output voltage Vo proportional to the absolute temperature T is proposed. The linear relationship between V and T in the measurable temperature range of about 77-470 K is achieved using a commercial Si-pn diode. In this temperature-sensor the ac voltage change in the pn junction diode due to the temperature change is measured for a constant amplitude of superimposed ac small signal of current δI on the constant forward dc current I0. This sensor has merits that it can be calibrated at only one temperature point, that the output voltage is proportional to the absolute temperature T and that the ac signal circuits can be isolated from dc bias voltage circuits. In addition, we have ascertained that a square wave as the superimposed ac signal of current δI is superior to the sine wave because of easy connection to the digital circuits and easy measurement of the amplitude of the ac output voltage.
