A method of testing an amplifier to establish its distortion characterstics due to intermodulation products.

摘要

A method of analysing the distortion produced by a linear power amplifier (20) is described. In this method two tones are applied to the amplifier and the resulting down-mixed signal is subjected to an FFT in order to derive the spectrum and plot the amplitude and phase distortion against the two tone amplitude. Analysis of the results of such testing allows the pre-distortion circuits (8,10,12) to be designed to compensate for distortion produced by the amplifier over the complete operating frequency range of the transmitter. <IMAGE>