Intelligible Crosstalk in Nonlinear Amplifiers: Calculation of AM-PM Transfer

This concise paper analyzes the transfer of amplitude modulation from one sinusoidal carrier to phase modulation of other carriers passing through the same memoryless nonlinear device. It gives exact expressions for the AM-PM transfer coefficient, which is one part of the mechanism that leads to intelligible crosstalk, and the expressions are valid for sinusoidal carriers in the presence of Gaussian noise through devices with known amplitude and phase characteristic. Two particular input signal combinations (two carriers with a given level difference, and a large number of small carriers) are considered in more detail, and the expressions are applied to a typical TWT characteristic.