A High-efficiency DC-to-RF/RF-to-DC Conversion Module with Zero-threshold FET for Bidirectional Wireless Power Transfer

A high-efficiency DC-to-RF/RF-to-DC conversion module has been developed at 10-MHz band for bidirectional wireless power transfer systems, based on an operation similarity between transistor amplifier and rectifier. It operates as an amplifier for converting a power from DC to RF, and also operates as a rectifier for converting one from RF to DC. The same drain-side circuit can be used for both operations based on the operation similarity. On the other hand, the gate-side circuit was adjusted so that higher efficiency operations were obtained for both operations. In addition, by using a zero-threshold transistor, a gate bias supply is not required on this module. At 10 MHz, the fabricated module exhibited a maximum drain efficiency of 68% and a maximum power-added efficiency of 66% in the amplification operation, and a maximum RF-to-DC conversion efficiency of 60% in the rectification operation.