Linearization of Class B Amplifier and Application to Outphasing Systems

This paper proposes the study of the impact of the linearization of class B amplifier used in outphasing systems. We show that a predistorted amplifier can provide considerable performance gain in linearity with good efficiency when compared to classical MILC architecture and to a standard class B amplifier. The results are validated for 16QAM signal using a RRCF with a roll-off factor of 0.2. Different backoff levels are considered and evaluated in terms of efficiency and linearity using EVM (Error Vector Magnitude) factor and adjacent channel interference ACI. The amplifiers used are based on realistic class B devices available in CAD simulators. The cosimulation is done using ADS software, with analog and digital parts, and MATLAB software. The MATLAB software allows us to determine the predistortion function and is introduced in ADS model.