RTD-based smart temperature sensor: Process development and circuit design

Planar resistance temperature detector, RTD, can be manufactured with microelectronics processing techniques. However, the manufactured planar resistor requires an extra step for adjustment of the 0degC reference resistance,
R

₀
. In this paper, we have evaluated the fabrication of nickel-RTD transducers for smart temperature sensors. By applying the smart sensor concept, the resistance adjustment step is avoided, as the calibration curve can be stored in the Transducer Electronics Datasheet (TEDS). The RTDs have been fabricated by thermal evaporation of nickel onto an alumina substrate. Calibration curves have been measured as a function of temperature, and a high linearity is observed. Two different prototypes for the conditioning and processing electronics are analyzed.