A Discrete Newton's Method for Gain Based Predistorter

Xiaochen LIN, Minglu JIN, Aifei LIU

School of Electronic and Information Engineering Dalian University of Technology, Dalian, P.R.China.

DOI: 10.4236/ijcns.2008.11003                

Abstract

Gain based predistorter (PD) is a highly effective and simple digital baseband predistorter which compensates for the nonlinear distortion of PAs. Lookup table (LUT) is the core of the gain based PD. This paper presents a discrete Newton’s method based adaptive technique to modify LUT. We simplify and convert the hardship of adaptive updating LUT to the roots finding problem for a system of two element real equations on athematics. And we deduce discrete Newton’s method based adaptive iterative formula used for updating LUT. The iterative formula of the proposed method is in real number field, but secant method previously published is in complex number field. So the proposed method reduces the number of real multiplications and is implemented with ease by hardware. Furthermore, computer simulation results verify gain based PD using discrete Newton’s method could rectify nonlinear distortion and improve system performance. Also, the simulation results reveal the proposed method reaches to the stable statement in fewer iteration times and less runtime than secant method.

Keywords

Predistortion, Discrete Newton’s Method, Power Amplifiers (PAs), Lookup Table (LUT)

Conflicts of Interest

The authors declare no conflicts of interest.

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