Skip to Main Content
In this paper, a low-power CMOS smart temperature sensor is presented. The temperature information extracted using substrate PNP transistors is digitized with a resolution of 0.03°C using a precision switched-capacitor (SC) incremental ΔΣ A/D converter. After batch calibration, an inaccuracy of ±0.25°C (±3) from -70°C to 130°C is obtained. This represents a two-fold improvement compared to the state-of-the-art. After individual calibration at room temperature, an inaccuracy better than ±0.1°C over the military temperature range is obtained, which is in-line with the state-of-the-art. This performance is achieved at a power consumption of 65 μW during a measurement time of 100 ms, by optimizing the power/inaccuracy tradeoffs, and by employing a clock frequency proportional to absolute temperature. The latter ensures accurate settling of the SC input stage at low temperatures, and reduces the effects of leakage currents at high temperatures.
Date of Publication: May 2013