In this thesis, a direction-reconfigurable wide-input-range radio frequency energy harvesting system is described. In order to improve the receiving power and the performance in low power range, three blocks of optimization are placed in different part of the system. Subse quently, a two paths 3-stage body biased cross-coupled differential-drive rectifier with antenna beam forming control and 3-bit capacitor bank is designed and fabricated in a standard 180nm CMOS technology. The rectifier is brought at resonance with four high-Q patch antennas by means of a control loop that compensates for any variation at the antenna-rectifier interface and a beam forming control that change the largest receiving direction of the antennas to allow higher power input in multiple directions. A body-bias method with cross-coupled capacitors and a diode to limit the body-bias voltage makes the rectifier works better in low power range.
The chip is integrated with four patch antennas. Measurements in an anechoic chamber at 2.45 GHz demonstrate a–10dBm sensitivity for 1 V output across a capacitive load. The end-to-end power conversion efficiency reaches 65% at–6dBm. ... Read more