High-Efficiency and Wide-Dynamic-Range Rectifier Based on Power Reflection for Wireless Power Transfer in Sensor Networks

Abstract

This paper proposes an efficient and wide dynamic range rectifier based on power reflection structure. The rectifier consists of a branch-line coupler and two sub-rectifiers operating at different input power levels. The branch-line coupler is used as power reflection structure. Due to the electromagnetic symmetry of the branch-line coupler and the non-linear characteristics of the rectifier, the power reflection structure can reflect mismatched energy caused by load variations or input power fluctuations back into the sub-rectifier, which can improve the reflection coefficient of the rectifier. For validation in different application scenarios, two rectifiers operating at 5.8 GHz were designed, fabricated, and characterized. For the proposed rectifier I (with load resistances RL1 = 750Ω and RL2 = 300Ω), the measured PCE maintains exceeding 50% when the input power ranges from 8 to 29.2 dBm, and the peak PCE is 68.01% at 18 dBm input power. While for rectifier II (with load resistances RL3 = 800Ω and RL4 = 300Ω), the measured PCE remains over 50% with input power from −1.2 to 28.8 dBm, and the peak PCE is 68.51% at 15 dBm input power. Theoretical analysis and performance comparison are carried out that excellent performance of proposed rectifiers in extending the input power range, which can widely apply in WPT system.