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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\mathrm {TH}}$</tex-math> </inline-formula> cancellation (IVC) technique achieves an ultrawide high-power conversion efficiency (PCE) input power range for an RF energy harvesting. Furthermore, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\mathrm {TH}}$</tex-math> </inline-formula>-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-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>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.