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poWEr aMplifiEr
linEarization
6.1 Introduction
Power amplifiers (PAs) are necessary components in communication
systems and they are nonlinear in a certain operating region. Power
amplifier nonlinearity results in spectral broadening, which leads to
adjacent channel interference (ACI) and superfluous radiation. One
way to avoid these impacts is to back off the power amplifier from its
saturation point or from the nonlinear region, but this causes deg-
radation in power amplifier efficiency that is not desired (typically
less than 10%) (Wright, 2002). More than 90% of the direct current
(DC) power is lost and turns into heat, hence other methods need
to be investigated in which the spectrum broadening can be sup-
pressed while the power efficiency is ...