New design of RF rectifier for passive UHF RFID transponders

A novel diode-connected MOS transistor for ultra-high-frequency (UHF) micro-power rectifiers was presented, and a high efficiency N-stage charge pump voltage rectifier based on this new diode-connected MOS transistor was designed and implemented. The new diode-connected MOS transistor and the rectifier are designed and fabricated in SMIC 0.18-μm 2P3M CMOS embedded EEPROM process. The structure design of the new diode achieved 315 mV turn-on voltage, and 415 nA reverse saturation leakage current. Compared with traditional rectifier, the rectifier using the presented diode-connected MOS has higher power conversion efficiency (PCE), higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the amplitude ranging from 0.8 to 1.8 V, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.02 V, and its ripple coefficients are less than 1%.