Modelling of nonlinear elements exhibiting frequency-dependent AM/AM and AM/PM transfer characteristics

In recent years there have been some significant technological advancements in the design of solid power amplifiers (SSPAs). These have made the replacement of travelling wave tube amplifiers (TWTAs) by SSPAs possible and economical, and have stimulated the interest in modelling and analysis of nonlinear elements with memory such as SSPAs. This paper proposes two simple models for a class of nonlinear elements which can be represented by frequency-dependent AM/AM and AM/PM characteristics. The simplicity of these models makes them appealing for analysis and simulation considerations. With these models, the analysis techniques that have been developed to study the behavior of signals through effectively memoryless nonlinear elements such as helix-type TWTAs can directly be applied. Straightforward identification schemes associated with these models are also given.