Dynamic range and other fundamentals of the complex Bessel function series approximation model for memoryless nonlinear devices

An explanation is given of the application of the complex Bessel function series approximation model of the memoryless amplitude and phase characteristics of nonlinear devices. Confusion had arisen because of the choice of a value of a parameter in the approximating expression. The practice had been to choose this simply as though it was just an arbitrary constant which scales the input, or as an optimizing parameter in the effort to get a best fit of the approximation to the measured data. By examining the derivation of the particular approximation, a determining and important link between this parameter and the desired operating dynamic range of the nonlinear characteristic being approximated is shown. How values for this parameter are calculated in terms of input overdrive relative to device saturation is also shown. In examining the origin of the approximating expressions, an alternative and simpler derivation to that given by J.C. Fuenzalida et al. (1973) is presented that is based on the work of M.J. Eric et al. (1972)