A sub-μW Fully Integrated Compact CMOS Temperature Sensor for Passive RFID Applications

This paper introduces a fully integrated miniature temperature sensor based on CMOS technology for passive Radio Frequency Identification (RFID) tags. The sensor has a simple architecture that consists of a sensing circuit, current-controlled oscillators (CCO), a Control circuit, and a frequency to digital converter(FDC). Moreover, it is designed without using any current, voltage, or clock reference circuits and operate in sub-threshold region to minimize the power consumption. The proposed temperature sensor is realized in a standard $0.18 \mu \mathrm{m}$ CMOS technology with an active area of 0.018 mm
²
. With a supply voltage of 0.5V, the sensor has a power consumption of 542.2 nw with a resolution of 0.14 °C. Furthermore, the experimental results illustrate that the proposed work attains an accuracy of −1.58 /+1.38 °C across −40 °C to 125 °C temperature range and a Resolution FoM of 1.06 pJ.K
²
.