A multitone model of complex enveloped signals and its application in feedforward circuit analysis

Analytical tools that characterize nonlinear systems are essential and need to be developed for initial rapid optimizations and understanding of the system performance. Modeling of the input signal is a crucial part of this task. In this paper, a multitone representation for an arbitrary double-side banded (symmetric spectrum around carrier frequency) stochastically not well-defined signal and its application to a feedforward circuit, which involve two nonlinear amplifiers, couplers, phase, and delay units are presented. Amplitude and phase aspects of the model are particularly highlighted and verified with RF simulations performed by real power-amplifier models and components.