A Direction-Reconfigurable Wide-Input-Range Radio Frequency Energy Harvesting System

Abstract

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.