A difference frequency technique for improving IM performance of RF amplifiers

A difference frequency technique for reducing the IM product levels in a no nlinear RF amplifier is presented. The technique is based on the standard t wo-tone test. The two sinusoid signals together with their difference frequ ency signal are fed into the amplifier. CAD simulation shows that the third -order IM level at the output of a nonlinear amplifier can be reduced using this technique. The results of a related experiment are reported, which ga ve a measured of 50 dB reduction in the level of the third-order intermodul ation without affecting the fundamental power levels. (C) 2000 John Wiley & Sons, Inc.