A simple lumped electrical model for an RF MEMS switch considering lossy substrate effects

This work focuses on electrostatically actuated micro-electro-mechanical systems (MEMS) capacitive switches, intended for adaptive output stage of power amplifiers. These devices are particularly attractive because theoretically they are capable of very high quality factor values due to the air gap between plates and the low resistivity of lines and bridge. On the other hand, substrate parasitic effects, overlooked up to date, can seriously impair device performance. In this paper, we introduce a lumped element equivalent circuit taking into account substrate effects. Model validation is based on measurements carried out in the 50 MHz-40 GHz range.