A switched‐capacitor‐assisted wireless power transfer system with regulating TX power and fast global loop

Abstract

Wireless power transfer systems demand a regulating transmitter (TX) for global loop control and also a regulating receiver (RX) for its local loop. This design broadens the TX output power range, by merging a switched capacitor (SC) circuit with only 3 switches and 1 flying capacitor to boost the output power of the Class-D power amplifier. In addition, the transmitting power can be regulated by the duty ratio of the SC, improving the end-to-end power transfer efficiency under different load conditions. Moreover, the system obtains fast load transient response, with the help of a light-to-heavy load transient enhancement scheme in the TX and the hysteretic control in the RX. Designed in a 0.18-μm BCD process, this work achieves 3.1 W maximum RX output power, 67.6% peak total efficiency, and 50 μs response time during the light-to-heavy load transient simulation.