A 0.002-mm2, 2.9-μW Pulse-Frequency-Modulation based Temperature Sensor with 40-mK Resolution

This article presents a compact CMOS temperature sensor for IoT (IoT) temperature measurement with a small area, high energy efficiency, and wide temperature range. Pulse frequency modulation (PFM) is used in this design because of its large dynamic input range and adjustable dynamic output range. The improved temperature-sensitive and monostable circuits are used to ensure the linearity and resolution of the circuit output. The prototype chip was fabricated in the 180-nm CMOS process with an area of 2200 μm
²
. In the measurement range of -60 ℃ to 90 ℃, the proposed temperature sensor achieves a resolution of 40 mK with a conversion time of 7 ms. The resolution FoM achieves 32 pJK
²
and the area FoM achieves 0.096 pJ(mm
²
)
²
with a power consumption of 2.9 μW.