Low-Power CMOS Temperature Sensors With RF Energy Harvesting for EPC Gen-2 RFID Tags

The consumer electronics industry has seen rising demand for passive sensor chips, particularly high-precision, low-power variants, in recent years. Responding to industry needs, this paper proposes a low-power, high-precision CMOS temperature sensor intended for RFID temperature sensing, which is compliant with the Electronic Product Code (EPC) Gen 2 standard. The design incorporates a multivibrator-based current-to-frequency converter that maintains high linearity and ultra-low power consumption across extended temperature ranges. Furthermore, this work presents an energy-efficient CMOS rectifier circuit with a fully complementary cross-coupled topology for enhanced RF energy harvesting, which utilizes diode-connected transistor ON-resistance to minimize leakage currents. The proposed EPC Gen-2 RFID tag is fabricated in a 0.18μm CMOS process occupying a silicon area of 0.39 mm2. Measurement results show that the sensor achieves the inaccuracy value of ±0.31∘C after one-point calibration, and the temperature sensor tag chip achieves a communication sensitivity of -17dBm, and the power conversion efficiency (PCE) of the proposed rectifier circuit can reach up to 62.4%.