QUANTIFYING THE EFFECT OF LOOK UP TABLE SIZE AND COEFFICIENTS COMPLEXITY FOR NON-LINEARITY COMPENSATION IN POWER AMPLIFIERS

I. A. HALEPOTO, W. KUMAR, T. D. MEMON, I. A. ISMAILI

Abstract


Power Amplifiers are the critical part of communication systems but they are nonlinear in nature. Look up Table (LUT) is one of the promising approaches for compensating the nonlinear effects of Radio Frequency (RF) power amplifiers. In this study we present a Memoryless Digital Predistortion (MDP) model to compensate the amplifier non-linearity based on updating the LUT coefficient iterations. Nowadays, the dual mode (Global System for Mobile communication (GSM) and EDGE (Enhanced Data rates for GSM Evolution) power amplifiers are in practice. In this work, we have proposed a single amplifier fulfilling EDGE specifications that can be implemented for base stations in order to compensate the required linearity and to improve overall system performance. MATLAB was used to simulate the proposed Class-B amplifier and a numerous simulation results were obtained and on that basis the best optimized LUT coefficient size complexity has been proposed. The proposed system also improves the maximum output power by optimizing the power at critical offset frequency. Moreover, Vector Magnitude (EVM) difference between estimated input and output results have also been calculated.

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