High-Efficiency Rectifiers With Wide Load Range Using Multiple Impedance Compression Networks

As a critical component for RF-to-DC conversion in RF electromagnetic wireless power transmission (WPT) systems, the RF rectifier significantly influences system performance. Traditionally, rectifiers are designed for specific loads at fixed frequencies and input power levels. However, even when the power-consuming devices remain the same in certain WPT scenarios, their equivalent load values may fluctuate due to varying operating conditions. High-efficiency rectifiers with a wide load range are proposed with multiple impedance compression networks (ICNs) in this paper. The proposed rectifiers are based on the conventional voltage doubler rectifier (VDR) configuration. First, our study shows that the load range of VDR is limited by circuit mismatch. Second, multiple impedance compression networks are used to address the mismatch problem and increase the load range. A detailed theoretical analysis is provided to explain the design methodology. Two rectifiers with different diode combinations are designed, fabricated, and tested for validation. The first design produces an RF-to-DC efficiency higher than 50% for a load range from 0.09 to 10.5 kΩ at an input power of 20 dBm. The second design achieves over 50% efficiency for a load range between 0.4 and 21.7 kΩ under an input power of 6 dBm. These results demonstrate the effectiveness of the proposed method in extending the load range. A comparison with existing works shows that the two rectifiers achieve the widest load range for both low and high input power levels. © 2004-2012 IEEE.