Analysis of the switching threshold in dual-level class-G modulated power amplifiers

A two-level class-G RF power amplifier system is analyzed. Measurements show that for low output powers there is an optimum switching threshold valid for both PAE and linearity while for higher output powers they diverge and there is a trade-off between PAE and linearity. This creates a region where the output power can be reduced from maximum to 2 dB (58%) back-off in which the PAE and linearity can be kept constant. Furthermore the power amplifier properties can be dynamically adjusted by changing the switching threshold voltage of the class-G modulator.