Performance Comparison of BJT and MOS Devices as Temperature Sensing Elements

The majority of the existing on-chip temperature sensing solutions rely on the thermal behaviour of the main parameters of BJT or MOS transistors. The success of their employment is correlated to their availability in standard CMOS processes; since usually MOS and BJT (even if parasitic) transistors can be implemented in the same technology, an in-depth analysis to select the more appropriate device for meeting the requirements of the considered application is needed. This paper, therefore, presents an extensive comparison between the temperature-related performance of these kinds of devices on the basis of simulated and experimental results collected from two different test chips, one for each sensing type, in the −40°C to +80°C temperature range; their performance is analyzed in terms of sensitivity, susceptibility to mismatch variations, inaccuracy, linearity and noise.