−11 to 7 dBm Power Range, Triple Band RF Energy Harvesting System With 99.9% Peak Tracking Efficiency and Improved PCE

This paper presents a triple-band radio frequency (RF) energy harvesting system with 99.99% peak tracking efficiency and the triple band rectifier achieves the 4.6% improvement in the power conversion efficiency (PCE). The proposed system has a power range of −11 to 7 dBm with the three bands targeted on 900, 1900, and 2400 MHz. In this paper, the voltage and power characteristics of the triple-band rectifier at each band are extracted as raw data by measurement. The DC-DC boost converter is applied to achieve the maximum power point tracking (MPPT), which exploits the hill-climbing MPPT method. The method is implemented with register logics and power calculator. The converter’s voltage range of 0.1V to 2V is achieved, and the converter facilitates to achieve the highest tracking efficiency of 99.99%, 98.57%, 99.85% at each bands. The performance is verified through experimental results showing PCE improvement and over 87% tracking efficiency in a wide power range at triple bands. The triple-band rectifier with transmission line is fabricated on FR-4 substrate with active area 35.7 cm2, and the DC-DC boost converter with MPPT is implemented in a $0.18~\mu \text{m}$ CMOS process with an active area of 0.94 mm2.