ACPR Improvement Limitations of Predistortion Linearizer for Nonlinear RF Power Amplifiers

Hyunchul KU  Kang-Yoon LEE  Young Beom KIM  

IEICE TRANSACTIONS on Electronics   Vol.E89-C    No.4    pp.466-472
Publication Date: 2006/04/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.4.466
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced RF Technologies for Compact Wireless Equipment and Mobile Phones)
adjacent channel power ratio (ACPR),  nonlinearity,  predistortion (pre-D),  power amplifier (PA),  spectral regrowth,  802.11g,  

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This paper investigates limitations of adjacent channel power ratio (ACPR) improvement in predistortion (pre-D) linearizer used with nonlinear RF power amplifiers (PAs) when the PA model is not perfectly acquired in pre-D design. The error between the physical PA and the nonlinear model is expanded by pre-D function and its power spectral density (PSD) works as limitations in ACPR improvement of the pre-D linearizer. An analytical estimation of ACPR limitations in RF PAs driven by digitally modulated input signal is derived using a formulation of autocorrelation function. The analysis technique is validated with the example of the memory polynomial PA model with the quasi-memoryless pre-D linearizer. The technique is also verified by comparing predicted ACPR limitation with measured limitation for a RF PA with 802.11g input signal.