Circulator-Based RF Energy Harvester with Wide Input Power Dynamic Range

Radio frequency energy harvesting (RFEH) is a promising solution for powering ultra-low-power (ULP) devices. However, capturing ambient energy is challenging due to low power densities and unpredictable RF power available in the surrounding environment. Moreover, conventional rectifiers exhibit limited power conversion efficiency (PCE) and a narrow input power dynamic range (PDR) due to impedance mismatch and power reflection losses. This paper presents a novel circulatorbased multi-branch RF energy harvester designed to efficiently recycle reflected RF power across multiple rectifier branches, significantly enhancing overall energy conversion efficiency and extending the operational power range. Simulation results at 900 MHz reveal that the proposed architecture achieves a PCE of 81% at an input power of 4 dBm and a PDR of 23 dB (spanning from −15 dBm to 8 dBm). These results demonstrate an 8 dB and 26% improvement in dynamic range and efficiency respectively compared to traditional single-rectifier designs, highlighting the effectiveness of the proposed solution.