A Dual-Band Simultaneous RF Energy Harvesting System With Globally Optimized 3-D MPPT and Efficiency Enhancement

Abstract

This article presents a globally optimized radio frequency (RF) energy harvesting system that leverages the novel concepts of 3-D maximum power point tracking (3-D MPPT) and collaborative source reconfiguration to achieve high MPPT accuracy and a wide input power range. The proposed 3-D MPPT coordinates the energy sources, optimizes the rectifier outputs, and regulates the rectifier stages for global efficiency optimization. A multi-level regulating DC–DC converter integrated with a reconfigurable rectifier enables synchronized dual-band RF energy harvesting. The reconfigurable buck–boost converter employs hysteretic control to regulate each rectifier output voltage at its respective maximum power point (MPP) and delivers a stable output through pulse-frequency modulation (PFM) with adaptive inductor on-time. The DC–DC converter dynamically connects a rechargeable battery (emulated by a power source and a resistor) to either the source or the load, supplementing insufficient energy or recovering surplus energy, thereby significantly extending the input power range. Fabricated in a 180-nm CMOS process, the prototype dual-band RF energy harvesting interface achieves a peak end-to-end efficiency of 71%, a sensitivity of −24.1 dBm, and wide high-power conversion efficiency (PCE) input power ranges of 15.5 and 20.5 dB at 433 and 900 MHz, respectively.