UHF power conversion with GaN HEMT class-E2 topologies

This paper reviews the use of UHF double class-E (class-E²) topologies for dc/dc power conversion. After introducing this attractive resonant converter in the context of the time-reversal duality principle, two different lumped-element networks are described for appropriately terminating the drain of the switching devices. Recent implementation examples, taking advantage of GaN HEMT processes, are then presented. The potential for a fast dynamic response is validated (with a slew rate over 2 V/nS), while also the feasibility for an appropriate operation without requiring external RF gate driving signals. A solution for approximating a load-insensitive operation is finally exposed.