Digital predistortion techniques based on envelope feedback

Abstract

A new digital predistortion (PD) technique based on envelope feedback is proposed for linearization of power amplifiers (PAs). Unlike conventional DPD techniques that need frequency down converters (FDCs) in the feedback path to recover the complex envelope of the PA output, the proposed technique does not need an FDC. Instead it employs two envelope detectors, estimating the envelopes of the difference between the PA input and output signals, and the difference between the PA input`s complex conjugate and PA output signals. Based on those two envelope feedbacks and the piecewise constant PA mode, it is shown that the PA identification can be accomplished. Simulation results show that the performance of the proposed DPD is comparable to the conventional DPD employing a complete FDC.