Megahertz-Range Wireless-Power-Transfer Rectifiers Resonant To Regulate

As more products are designed with wireless charging capability, resonant wireless-power-transfer (WPT) technology is increasingly present in the wireless market. Having faster and more reliable charge rates—while using less expensive or space-consuming electronics—is a major goal for this industry. At the Korea Advanced Institute of Science and Technology, Jun-Han Choi, Sung-Ku Yeo, Seho Park, Jeong-Seok Lee, and Gyu-Hyeong Cho designed and tested several resonant regulating rectifiers for enhanced WPT capability at 6.78 MHz.

On 0.35-micrometer bipolar-CMOS-DMOS (BCD) technology, the team is able to design RWPT circuits that can harvest power to 6 W at 86% efficiency using both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The proposed resonant-regulating-rectifier designs do not require an additional inductor for switch-mode regulation, as the resonant tanks are operated using phaser-transformed inductance. Only three switches are used in a rectifier design that achieves 6 W of transferable power. Such a feat is impressive when compared to other resonant-regulating-rectifier systems that have been reported, which have less than 1 W of available power at 13.56 MHz. See “Resonant Regulating Rectifiers (3R) Operating for 6.78 MHz Resonant Wireless Power Transfer (RWPT),” IEEE Journal of Solid-State Circuits, Dec. 2013, p. 2989.