An Improved Adaptive Digital Predistortion Using Discrete Newton´s Method

Adaptive digital baseband predistortion is a highly effective and simple linearization technique which compensates for the nonlinear distortion of PAs. This paper presents an improved adaptive technique using discrete Newton´s method efficiently applied to digital baseband lookup table (LUT) predisortion. We simplify and convert the hardship of adaptive updating LUT to the roots finding problem for a system of two element real equations on mathematics. And we deduce the improved adaptive iterative formula used for updating LUT based on discrete Newton´s method. 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 the LUT baseband predistortion 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 than secant method.