Performance analysis of a novel real-time closed-loop technique for non-linearity correction of power amplifiers

In this paper we discuss performance results of a novel real-time closed-loop power amplifier (PA) linearization technique that has originally been proposed by Ahmed and Li [1]. The novel approach performs on-the-fly prediction and measurement of the PA AM/AM and AM/PM non-linearity, stores such non-linear characteristics and calculates their inverse functions in order to pre-distort the base-band amplitude and phase signals modulating the PA such that the combination, or the resultant, of the pre-distorter and the PA leads to a linear behavior at the output of the PA. We present a model of our predictor based approach and evaluate its performance for an GSM/EDGE application. The key performance metrics we evaluate have been based on the GSM/EDGE requirements, such as the Error Vector Magnitude (EVM), Switching Transients (ST), Adjacent Channel Power Ratio (ACPR), transmit time mask, modulation spectrum and PAE.