Efficient Baseband Digital Predistorter Using Lut for Power Amplifier (PA) with Memory Effect

B. Feuvrie^{1, 2}, M. Diop^3, and Y. Wang¹

¹IREENA Ecole polytechnique – de l’université de Nantes, Nantes, France

²IUT GEII Nantes - Site Fleuriaye, Av. du Prof J. Rouxel, Carquefou, France

³Ecole Supérieure Polytechnique, UCAD, BP 5085, Dakar-Fann, Sénégal

Cite this paper

B. Feuvrie, M. Diop and Y. Wang. Efficient Baseband Digital Predistorter Using Lut for Power Amplifier (PA) with Memory Effect. American Journal of Electrical and Electronic Engineering. 2014; 2(3):72-81. doi: 10.12691/AJEEE-2-3-3

Abstract

Modern communications systems will have to integrate multiple radio technologies to support a large number of wireless standards (WLAN, WPAN…). This system should operate with third generation (3G) air interface standards, where non constant envelope modulation formats (MQAM, OFDM…) are required. The amplification of a modulated signal with large variation of envelope introduces distortions when the input-output characteristic is nonlinear. These distortions are particularly important when the power amplifier (PA) has non-linear memory effects with a wideband signal. The technique proposed in this paper aims to fight against this phenomenon by optimizing the method developed in the laboratory for a real-time implementation. This technique is able to provide exactly the reverse characteristics of a PA modeled by a Hammerstein model in base band. Its principle is to find the largest real root of a polynomial related to the analytical model of the PA and to the input signal to be amplified to calculate a pre-distorted signal. To reduce significantly the computation time, an implementation by the LUT method is proposed. This method uses two pre-distortion principles and can be implemented on a FPGA board with table bases method known for simplicity including in the same way the correction of the memory effect.

Keywords

nonlinear distortion with memory, digital pre-distortion, power amplifier (PA), Hammerstein model, Look Up Table (LUT)

Copyright

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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