A high efficiency radio frequency energy harvester is proposed in this paper.It consists of a number of antennas,and each antenna is cascaded by an impedance matching network and a multi-stage Villard voltage doubler.The radio frequency signal received by the antenna is firstly fed to its impedance matching network and a two-stage voltage doubler,and then two of such paths are put into parallel to collect current,which is followed by a six-stage Villard voltage doubler to boost the voltage.Finally,the outputs of all the six-stage voltage doublers are paralleled to increase the overall current,and thereby improve the power conversion efficiency.The parameter of each component is determined by simulation with ADS.The harvester is tested both in air and in tissue.When operating in the frequency range from 0.5 GHz to 3 GHz and a transmitted RF power from 5 dBm to 25 dBm,the harvested voltage and the efficiency on a 1kΩ load are 0.01~6.22 V and 2%,respectively.While in the tissue (a piece of porch in this case),the harvested voltage and the efficiency on the same load are 0.01~3.5 V and 1.5%,respectively.The harvested voltage and efficiency of the proposed multi-channel RF energy harvester are about 2V and 1% higher than a single-antenna RF energy harvesting circuit,respectively.%文中提出了一种高效率的射频能量收集器,其主要由天线阵列、阻抗匹配网络和多级Villard倍压整流电路构成.为提高效率,采用多个天线构建多路射频能量收集器,且每两路天线接收信号首先传输给与之对应的阻抗匹配网络和2级倍压整流电路,然后并联汇集电流,再经6级倍压整流电路来提升电压,最后将所有6级倍压整流电路在输出端并联来增大电流.通过ADS仿真确定了阻抗匹配网络和倍压整流电路中各元件的具体参数,在空气和生物体组织两种介质中对所设计的电路进行了测试.当工作频率为0.5~3 GHz,射频信号强度为5~25 dBm,负载电阻为1 kΩ时,在空气中的输出电压为0.01~6.22 V,能量转换效率为2%;在生物体组织中的输出电压为0.01~3.5 V,能量转换效率为1.5%.文中所提出的多天线射频能量收集器的输出电压和能量转换效率分别比单天线射频能量收集器高2 V和1%.
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