An Outphasing Transmitter Using Class-E PAs and Asymmetric Combining: Part 1

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  • Author: Ramon Beltran, Frederick H. Raab, and Arturo Velazquez
High efficiency linear amplification is of great interest in modern communication systems as it increases talk time, decreases power consumption, decreases heat dissipation, and improves reliability. The efficiency of linear power amplifiers (PAs) is highest at the peak output power (PEP) and decreases significantly for low amplitudes, Signals with time-varying amplitudes (amplitude modulation) therefore produce time-varying efficiencies, the probability density function (pdf) of the envelope is a means of how much time an envelope spends in certain amplitude level, Hence, obtaining a high average efficiency therefore requires acombination of amplifier and architecture that improves efficiency at low as well as high amplitudes. It is achieved by combining highefficiency power amplifier and a transmitter architecture such as envelope elimination, Doherty, or outphasing.