High-Efficiency CMOS Rectifier Circuit for UHF RFID Using Threshold Voltage Compensation Technique

In this paper, a CMOS rectifier circuit using a threshold voltage compensation technique is proposed for UHF RFID systems. The rectifier circuit includes a three-stage charge pump, a current reference circuit, and a bias circuit. The charge pump adopts the structure of NMOS and PMOS cross-rectification, the current reference is a low-power circuit, and the bias circuit generates a precision voltage to compensate for threshold losses in the charge pump. The threshold voltage compensation technique improves the power conversion efficiency of the rectifier circuit. The rectifier circuit is designed in UMC 110nm CMOS process, and the simulation results show that a 1.2V DC output voltage is obtained with 400mV input voltage, 915MHz input frequency, and 100KΩ load. The power conversion efficiency is 47.74% at -16.5 dBm input power.