Nonlinear Compensation Technologies for Microwave Power Amplifiers in Radio Communication Systems

Toshio NOJIMA  

IEICE TRANSACTIONS on Electronics   Vol.E82-C    No.5    pp.679-686
Publication Date: 1999/05/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Low Distortion Technology for Microwave Devices and Circuits)
linearizer,  predistortion,  feed-forward,  microwave,  radio communication,  mobile communication,  

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Technologies used to characterize and compensate nonlinearities in microwave power amplifiers are discussed. First, a complex power series representation that allows both amplitude and phase nonlinearities to be dealt with simultaneously is proposed, and in order to estimate the 3rd-order complex coefficient phase of practical amplifiers, two kinds of experimental measurement methods are proposed. Next, the fundamental circuit configuration of IF cuber predistortion linearizer that compensates 3rd-order intermodulation distortion is derived from a nonlinear analysis using complex power series representation. Two practical cuber predistorters for the 6-GHz TWTA and the 800-MHz FET-PA are demonstrated. Moreover, the unique nonlinear compensation technology of side-band inversion is introduced for microwave relay system using TWTAs. Finally, the self-adjusting feed-forward (SAFF)-PA developed for digital cellular base stations is reviewed.