This paper presents a dual-antenna energy harvesting (EH) system using full-energy extraction (FEE) to reduce the buffer capacitor requirement and improve the input power response speed. Instead of using large buffer capacitors (in the order of $\mu \text{F}$ ) at the rectifier output, the proposed FEE technique can efficiently harvest the incoming 915MHz radio-frequency (RF) energy using only a 1-nF capacitor per channel, while reducing the operating frequency of the subsequent DC-DC converter for power loss minimization. The two most popular RF rectifiers are investigated to relax the energy extraction degradation due to impedance mismatch. The boost DC-DC converter combines the harvested energy from the dual-inputs through the FEE controller. Fabricated in standard 0.18- $\mu \text{m}$ CMOS and wire-bonded on an FR4 PCB, the dual-antenna EH system with the DC-DC converter operating typically at 6.25kHz demonstrates a measured peak system efficiency of 75.2% at an output power of $22.6~\mu \text{W}$ using only two 1-nF buffer capacitors at 1- $\mu \text{F}$ load. With a significant buffer size reduction than prior art at similar efficiency/power level, a short startup time of ~ 45ms is achieved when the output rises from 0 to 1 V at $15.5~\mu \text{W}$ total rectifier output power, corresponding to 90% startup time reduction over the conventional approach.

中文翻译：

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使用全能量提取并改善输入功率响应的高效双天线射频能量收集系统

本文提出了一种双天线能量收集 (EH) 系统，该系统使用全能量提取 (FEE) 来减少缓冲电容器需求并提高输入功率响应速度。而不是使用大缓冲电容器（按 $\mu \text{F}$ ) 在整流器输出端，建议的 FEE 技术可以有效地收集传入的 915MHz 射频 (RF) 能量，每个通道仅使用 1nF 电容器，同时降低后续 DC-DC 转换器的工作频率，以最大限度地减少功率损耗。研究了两种最流行的 RF 整流器，以缓解由于阻抗不匹配导致的能量提取退化。升压 DC-DC 转换器通过 FEE 控制器组合从双输入收集的能量。以标准 0.18- 制造 $\mu \text{m}$ CMOS 和引线键合在 FR4 PCB 上，带有 DC-DC 转换器的双天线 EH 系统通常以 6.25kHz 的频率运行，在输出功率为 75.2% 时，测得的峰值系统效率为 75.2%。 $22.6~\mu \text{W}$ 在 1- 处仅使用两个 1-nF 缓冲电容器 $\mu \text{F}$ 加载。在类似的效率/功率水平下，缓冲器尺寸比现有技术显着减少，当输出从 0 V 上升到 1 V 时，可实现约 45 毫秒的短启动时间 $15.5~\mu \text{W}$ 总整流器输出功率，相当于比传统方法减少 90% 的启动时间。