Influence of the envelope coding on a class E amplifier efficiency in polar architectures

This study deals with high efficiency architectures enabling transmission of high PAPR signals. High PAPR signals result from new communication standards targeting high data rates and spectral efficiency. Polar Architectures, proposing the Envelope Elimination and Restoration (EER), code non constant envelope signals in order to obtain constant envelope signals at the input of the power amplifier (PA) and to use the PA in switched mode. PA efficiency is affected by the signal coding and the frequency of the envelope modulator. First, this paper presents the effect of the envelope binary distribution after coding on the efficiency of a class E power amplifier. Then, the binary distribution of a mobile WiMAX signal is observed when it is coded with a Pulse Width Modulator in EER architecture and with a low pass Sigma-Delta Modulator in a polar architecture. This analysis yields to conclude on the influence of the coding technique on the class E amplifier efficiency and presents an estimation of the efficiency that could be expected with both architectures.