Any active network can be described by the power series. This term is correct in the first approximation, when the system has no memory. Memory effects of an active system are caused by a time-varying phase response, which is, in turn, manifested in the frequency response. This phase response is referred to as the amplitude modulation (AM) to phase modulation (PM) characteristic. This phenomenon describes how the phase response is affected by input power. Under these terms of memory, the system is described by a Volterra series. The power series presentation here considers AM- to-PM effects only and the associated calculation is scalar only, which means a simple polynomial with real coefficients.
Online access to SPIE eBooks is limited to subscribing institutions.