Load pull analysis of Chireix outphasing class-E power amplifiers

Class-E amplifiers have the potential to deliver the high efficiency required for the next generation wireless systems. A class-E amplifier is not an ideal current or voltage source as is required for the traditional analysis of the Chireix outphasing topology. It requires a phase modulated input signal and has a non-linear transfer characteristic which is a function of the load impedance. In this paper, we present a load pull analysis technique to characterize the efficiency performance of class-E amplifiers in a Chireix outphasing topology. An operating load locus based on the load pull analysis has been defined in the load pull plane of each amplifier. The defined load locus is used to find the nonlinear transfer function, efficiency, output power, input drive phase and losses associated with the Chireix outphasing topology. This analysis can also be used to characterize the Chireix outphasing performance of other amplifier classes.