Modelling of the RF self-actuation of electrostatic RF-MEMS devices

This paper presents a study of the self-biasing of RF-MEMS shunt switching devices, and tunable capacitors per extension, taking into account the negative feedback on the electrostatic force introduced by the mismatch. The influence of the RF-power on the DC-actuation is included in the normalised analytical formulas developed for any shunt mismatch (capacitive or not) involving a moving armature. We demonstrate the possibility to overcome the pull-in instability by using the power-actuation and the importance of the mismatch to accurately predict the actuation characteristics. Our model can account for parabolic and close-to-linear dependence between DC-bias and RF-power at pull-in.