Multitone power and intermodulation load-pull characterization of microwave transistors suitable for linear SSPA's design

In this paper, an experimental load-pull characterization of microwave transistors operated under N-tone excitations (2 less than or equal to N less than or equal to 32) is presented, Such characterization is very useful to investigate the linearity of high-power amplifiers via intermodulation distortion analysis, All the measurements were carried out using a newly developed multiline measurement system which uses an arbitrary waveform generator (AWG) to generate the spectrum of any N desired tones and a microwave transition analyzer (MTA) as a vector receiver, The measured intermodulation rejection (IMR) behavior, as the number of tones increases, is compared with previously published theoretical results, Constant output power contours and IMR contours in the Gamma(L)(f(0)) plane for different number of tones are presented and discussed, The dependency of the LMR on the biasing conditions and the carriers' phase distribution is also investigated.