Introducing complex functional link polynomial filters

Abstract

The paper introduces a novel class of complex nonlinear filters, the complex functional link polynomial (CFLiP) filters. These filters present many interesting properties. They are a sub-class of linear-in-the-parameter nonlinear filters. They satisfy all the conditions of Stone-Weirstrass theorem and thus are universal approximators for causal, time-invariant, discrete-time, finite-memory, complex, continuous systems defined on a compact domain. The CFLiP basis functions separate the magnitude and phase of the input signal. Moreover, CFLiP filters include many families of nonlinear filters with orthogonal basis functions. It is shown in the experimental results that they are capable of modeling the nonlinearities of high power amplifiers of telecommunication systems with better accuracy than most of the filters currently used for this purpose.