The effects of quadratic AM-PM conversion in FDM multiple access communication satellite systems

A travelling wave tube amplifier such as those employed in FDM multiple access communication satellite repeaters is considered in this paper. The amplifier nonlinearity is assumed to follow an error-function characteristic and the AM-PM conversion is taken to be a quadratic function of the envelope of the input signal. A closed form expression, allowing for both arbitrary amounts of amplifier saturation and AM-PM conversion, is derived for the autocorrelation function of the amplifier output when the input is a Gaussian band-pass process.