RF to DC CMOS rectifier with high efficiency over a wide input power range for RFID applications

In this paper we present a RF-DC rectifier which operates over a wide range of input power by providing a regulated output DC voltage. The circuit solution we propose is based on a novel active load circuit which adjusts the output current as a function of the incoming RF power. This allows maximizing both the efficiency and sensitivity of the circuit. Circuit prototypes fabricated in 130nm CMOS technology start to operate at -14dBm, providing a regulated output voltage of 1.6÷1.8V in the -14÷1dBm RF input power at 868MHz. Noticeably, the circuit efficiency of the rectifier peaks at 45%, remaining above 30% in the -12÷+1dBm input power range.