Low cost 50W Class EF2 PA for Magnetic Resonance Wire-less Power Transfer Applications

Inhalt:
This paper presents the constant current Class EF2 power amplifier (PA) for magnetic resonance WPT with GaN devices, where the current output of the Class EF2 PA remains almost constant when the load impedance varies. The solution enables power transfer coil load of the WPT system to simultaneously support multiple devices and naturally supply the power demanded by receiver with open loop. The design methodology of Class EF2 PA will be discussed in detail, followed as a customer solution design for WPT. The Class EF2 PA can deliver 50W CW power at 6.78MHz, with 92% efficiency at 20V. PA design offers small footprint and enable for low cost low voltage applications.