Design of an Ultra-Wideband High-Efficiency Rectifier for Wireless Power Transmission and Harvesting Applications

The wireless power transmission and harvesting techniques is becoming more and more important in industrial applications. A wide operating bandwidth is always expected for these two techniques. However, the existing rectifying structures usually can operate only over a narrow bandwidth. To achieve the wideband and efficient rectifying, the variation of optimum input impedance for the rectifier over the operating band should be as small as possible. For this issue, the voltage doubler configuration is analyzed and proved theoretically to exhibit slowly changing optimum input impedance. Based on this unique property, the simplified real frequency is utilized as the universal design approach together with the theoretical calculation. For demonstration, two rectifiers have been designed, fabricated, and measured for different input power levels. The proposed rectifiers showed the good characteristics in both efficiency and bandwidth. The rectifier applied in the high-power scenario kept conversion efficiency higher than 50% from 0.6 to 3 GHz, which corresponds to a relative bandwidth of 133%. The other rectifier designed for the low-power scenario maintained conversion efficiency higher than 40% within a wide bandwidth of 73.1%. The simulated and measured results agree well with each other, which validates the proposed structure and design methodology.