Analyses of the optimal power load impedances measured in MMIC and hybrid configuration in the Ka band

Abstract

The authors deal with the main different behaviors of the optimal power load impedances for two devices (PHEMT) studied in two configurations (called "probing" or "hybrid") in power condition with an active load pull bench in Ka band (26-40 GHz). Contrary to what would be expected, the difference is not only a phase shift, which is usually the case at lower frequencies, but a gap in phase and magnitude between the optimal impedances. This behavior is presented. A linear electrical simulation has been achieved in order to explain these behaviors.