Analysis and practical performance of a difference frequency technique for improving the multicarrier IMD performance of RF amplifiers

This paper presents a difference frequency technique for IMD improvement in power amplifiers. The technique is based on feeding the original two tone signals and a signal which frequency is the difference frequency of the fundamental signals in to the amplifier. Theory, simulation and practical measurement are presented. The result of the related experiment which gave a two tones measurement of more than 40 dB reduction in the level of the third order IMD is reported.