High Efficient Integrated Power Receiver for a Qi Compliant Wireless Power Transfer System

Wireless Power Transfer (WPT) is an emerging technology with a huge variety of possible applications, including wireless charging of mobile devices like smart-phones or tablet computers. In this work, a WPT receiver system integrated on a silicon chip is proposed to maximize the efficiency of the system. The presented chip is produced in a low cost standard 130 nm CMOS process with a high voltage extension. This enables the on-chip integration of a full bridge rectifier with 12V power MOSFETs. A prototype system, designed for the use in mobile applications, has been developed based on the Qi Standard specifications. Different control strategies for the rectifier have been implemented and compared regarding their impact on the overall receiver system efficiency. The fully-active rectifier control technique enables the WPT system to decrease its losses and hence increase the system efficiency by more than 16% when compared to a passive approach. The experimental results confirm that the presented system is able to obtain a System efficiency of up to 88% at an output power of 1.8W.