AC-DC converter for wireless power transmission of energy harvesting system

In this study, a high-efficiency AC-DC converter is developed for a wireless power transmission system that transmits power generated from energy harvesting. RF power is transmitted in the frequency of 10-100 MHz, and power of -10 to 15 dBm is received by the AC-DC converter. A matching network is designed according to the received power from resonant coils, and the load resistor is optimized to obtain maximum output power. As a result, conversion efficiency ranging from 50% to a maximum of 87% is achieved in an RF power range of -10 to 15 dBm that has 10-100 MHz frequency. Compared to other converters, the implemented AC-DC converter shows not only 20%-40% higher peak efficiency, but also 20%-50% higher average efficiency. It is suitable for application in wearable devices or body area networks.