Stair-type parallel digital predistorter for power amplifier linearisation and harmonic reduction

Abstract

ABSTRACT In this study, cognitive radio systems are examined. As it is difficult to include all the candidate frequency bands of the wide spectrum of the primary channel using the filtering approach, we propose a stair-type parallel predistortion (PD) and implement it using a commercial wideband Gallium Nitride power amplifier. Parallel predistorters centred at different integer multiples of are used for constructing the PD to effectively reduce spectral regrowth of the fundamental signal as well the harmonics at different frequencies. Experimental results demonstrate that the spectral regrowth at and harmonic at are reduced by and , respectively. The obtained results establish the proposed PD with parallel predistorters as a predistortion technique for dynamic spectrum allocation systems such as cognitive cellular systems and CR networks.