Load-Invariant Double Class-E/F2 Resonant Topology for UHF DC-DC Power Conversion

This work addresses the design of a double class-E/F2 resonant power converter operating under a varying dc load at UHF band. Based on a RF GaN HEMT, the performance of a class-E/F2 power amplifier (PA) is compared through simulations with the one from a class-E PA using the same transistor. The efficiency enhancement potential offered by a second harmonic termination typical of class-F^-1 PAs, associated to a reduction of the transistor conduction losses, is however degraded by the losses in the passive elements due to the need for a more complex network interconnecting the inverting and rectifying parts of the converter. Measured efficiency results include a peak value of 75% and a profile above 60% for dc output power levels up to a 35% of the peak or nominal value (13.4 W)