Design of a High-Conversion-Efficiency X-Band Rectifier for Microwave Wireless Power Transmission

Microwave wireless power transmission technology has been applied to several applications with advantages, such as solar power satellites, remotely powered vehicles, surveillance platforms, wireless sensors, and radio frequency identification (RFID) tags. The design of a rectifier with high MW-DC conversion efficiency is crucial in microwave wireless power transmission technology due to its enormous influence in the overall system efficiency. Most of the studies of rectifier choose schottky diodes as the rectifying device [1-8]. However, due to the nonlinearity of the diode, it is hard to design a rectifier with high efficiency without large quantities of computer simulations, especially under large signals condition. Therefore, a theoretical analysis of diodes in a specific rectifier circuit is important. References [1] and [8] present two theoretical analysis methods based on one-diode circuit model. In this work, we will expand the one-diode model analysis further to voltage doubler model analysis. Mechanism of diodes in a voltage-doubler rectifier has been studied. From the diode junction voltage waveforms and diode current-voltage characteristic curves shown in Fig. 1, closed-form equations for the diode input impedance and efficiency have been derived and expressed as (1) and (2). The closed-form equations have been validated by comparing the calculated results with the simulated ones by the Advanced Design System (ADS) software. The comparison charts are shown in Fig. 2 and Fig. 3. The closed-form equations are applicable for microwave voltage-doubler rectifier and can be a useful tool for design. In this paper, a rectifier which is work at X-band has been designed and tested. The selection of diodes was based on their MW-DC conversion efficiencies which can be calculated by equation (2). The design of impedance matching network was based on its impedance which can be calculated by equation (1). The measured efficiency of the proposed rectifier is 72% which is in good agreement with the calculated results. This efficiency of the proposed rectifier ranks high on the list of the related works at X-band which are shown in Table. 1. [GRAPHICS] .