A simplified thermal model for lateral MOSFET and its application to temperature monitoring

Abstract

This work presents a novel model to describe the thermal dependence of source-drain voltage of metal-oxide-semiconductor field-effect transistors (MOSFETs) in saturation regime, justified and experimentally tested in n-channel and p-channel transistors. This model provides the temperature coefficient of source-drain voltage as a function of transistor parameters and the drain current as a compact, static dc and empirical model. To do so, an exhaustive thermal characterization of p-channel MOSFET (pMOS) 3N163 (Vishay Siliconix, USA) and n-channel MOSFET (nMOS) 3N170 (Linear Systems, USA) was carried out in the industrial temperature range of −40 °C to 85 °C. Experimental results are in agreement with the proposed thermal model in different current ranges depending on the transistor model, from 15 μA to 700 μA for 3N163 and from 200 μA to 5 mA for 3N170. Finally, the thermal model was applied to design a temperature sensor based on differential measurements of source-drain voltages in a pair of complementary MOSFETs, achieving an average sensitivity of 5.17 ± 0.13 mV °C−2, with a maximum linearity error of 1.1% for the industrial temperature range. This temperature sensor based on MOSFETs offers high sensitivity with a low number of devices and possible compatibility with current manufacturing processes.