Temperature Sensitivity of SOI-CMOS Transistors for Use in Uncooled Thermal Sensing

The temperature coefficient of current (TCC) of CMOS transistors implemented on silicon-on-insulator substrates is theoretically and empirically studied for its potential use in uncooled thermal sensing. Modeling and measurements show TCC values in subthreshold of more than 6%/K, better than state of the art microbolometer temperature coefficient of resistance, and less than -0.4%/K in saturation-comparable with metals. Models and measurements are shown for the TCC dependence upon operating point, temperature and channel length. A simple semi-empirical model for the TCC at subthreshold based on long channel approximation is suggested and shown to agree with measurements for channel length down to 0.35 /spl mu/m. The model and measurements show a logarithmic tradeoff between subthreshold current and the TCC, which is important in the design of sensors.