Efficiency enhancement techniques and a dual-band approach in RF rectifiers for wireless power harvesting

Efficiency enhancement techniques for CMOS rectifiers used in wireless power harvesting applications such as radio-frequency identification (RFID) or biomedical implants are overviewed. More specifically, three recently proposed efficiency enhancement techniques, namely, switched-capacitor gate-boosting scheme, auxiliary cell scheme and quasi-floating-gate biased scheme are presented in which based on the RF input level, the gate-drive voltage of switching transistors in the differential-drive rectifier architecture is enhanced. The proposed designs are laid out in standard 0.13-μm CMOS and their performance metrics are compared with the state-of-the-art differential structures. Through dynamically adjusting the input capacitance of the rectifier, a dual-band input matching scheme is presented which enables efficient power delivery at two distinct frequencies.