Development of Efficient Discrete Model and Error Analysis for Nonlinear RF Power Amplifiers in Wireless Communications

Hyunchul KU
Youngcheol PARK

IEICE TRANSACTIONS on Communications   Vol.E93-B    No.9    pp.2363-2369
Publication Date: 2010/09/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E93.B.2363
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
condition number,  least square,  memory polynomial,  memory effects,  nonlinear,  power amplifier,  sampling,  sensitivity,  

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This paper discusses an efficient discrete model for nonlinear RF power amplifier (PA) with long-term memory effects and analyzes its error. The procedure of converting RF signals and systems into a discrete domain is explained for a discrete baseband memory polynomial model. Unlike a previous simple memory polynomial model, the proposed discrete model has two different sampling frequencies: one for nonlinear system with long-term memory effects and one for input signal. A method to choose an optimal sampling frequency for the system and a discrete memory depth is proposed to minimize the sensitivity of the system for perturbation of the measured data. A two-dimensional sensitivity function which is a product of relative residual and matrix condition number is defined for least square problem of the proposed model. Examples with a wideband WiBro 3FA signal and a WCDMA 4FA signal for nonlinear transmitters are presented to describe the overall procedure and effectiveness of the proposed scheme.