A 2.4-GHz −33-dBm Sensitivity Battery-Free RF Energy Harvesting System With 17-dB Input Power Range

This brief presents a high-sensitivity battery-free radio frequency (RF) energy harvesting system with ultralow-power auxiliary modules. The proposed design implements two-stage energy conversion based on burst charging mode, achieving ultrahigh sensitivity by using an intermittent charging method that eliminates the charge pump’s loading effect on the RF rectifier. An all-nMOS RF--dc rectifier with internal ${V}_{\mathrm {TH}}$ cancellation (IVC) technique achieves an ultrawide high-power conversion efficiency (PCE) input power range for an RF energy harvesting. Furthermore, a ${V} _{\mathrm {TH}}$ -based voltage reference is introduced, enabling subthreshold operation of transistors with picowatt-level power consumption, thereby simultaneously improving both PCE and sensitivity. The proposed RF energy harvesting system is implemented with a 0.18- $\mu $ m standard CMOS technology. The results show that the system achieves a 55% PCE, a −33-dBm sensitivity, and a 17-dB input power range at 2.4 GHz.