Wide Range Temperature Sensors for Harsh Environments

Silicon-on-insulator (SOI) parts are designed for high temperature applications and the potential exists about their performance at cryogenic temperature conditions. In this paper, the performance of SOI devices and circuits were evaluated under extreme temperatures and thermal cycling. Two oscillator circuits were constructed using a new SOI 555 timer chip and used as temperature sensors in harsh environments encompassing jet engines and space mission applications. The circuits, were evaluated between -190degC and +200degC. The output of each circuit produced a stream of square pulses whose frequency was a function of the sensed temperature. The results indicate that both circuits performed relatively well over the entire test temperature range. In addition, the performance of either circuit did not undergo any change after subjecting the circuits to limited thermal cycling over the temperature regime of -190degC and +200degC, and the circuits were able to cold start at -195degC.