Linear radio frequency power amplifier design using nonlinear feedback linearization techniques

This paper presents the results of the research conducted on the feedback linearization of radio frequency (RF) power amplifiers (PA) used in digital communication applications. The proposed design takes into account not only the nonlinear behavior of the power amplifier but also its dynamic behavior. First, a faithful mathematical model of the voltage I/O characteristic of the PA is developed, i.e., a sigmoidal function model which closely describes its nonlinear gain behavior is derived and a multiplicative nonlinear feedback controller is applied to it to render the overall amplifier´s response linear. Simulation results obtained using Matlab/Simulink are presented, and power amplifier linearity properties are quantified in terms of the output power spectrum when the input is a BPSK waveform, the classic two-tone test, the white noise test, and the AM/AM and AM/PM conversion curves.