0.5 V 19 nW Smart Temperature Sensor for Ultra-Low-Power CMOS Applications

Abstract

The smart temperature sensor measures the room temperature and converts it to the digital domain, thus making it easier to process and store data. This work presents a fully integrated smart temperature sensor implemented in a 180 nm CMOS technology suitable for low voltage and ultra-low power electronic applications. The designed circuit uses a frequency to digital conversion topology, in which the frequency of an internal signal is linearly dependent on the room temperature. The minimum supply voltage for the designed circuit is only 0.5 V, while the occupied silicon area is 0.04 mm2, By utilizing a proper circuit topology and the power gating technique, very low power consumption of 19 nW for a sampling frequency of 100 Hz at 27 °C is achieved. Moreover, the sensor consumes nominally 190 pJ per conversion. The simulated inaccuracy using nominal (TT) transistor models is lower than 0.5 °C over a wide temperature range of -30°C to 100 °C.