The influence of mechanical shock on the operation of electrostatically driven RF-MEMS switches

A closed-form relationship between the insertion loss, the externally applied mechanical shock and the RF signal voltage of a capacitive RF-MEMS shunt switch is derived. It is shown that, based on this relationship, the minimum required mechanical stiffness of the suspended structure can be calculated. This allows determination of the minimum electrostatic switching voltage in a given process flow. The results are illustrated for specifications regarding shock resistance of electronic equipment as set out in MIL-STD-883. Even under the least severe test conditions, the shocks can affect the insertion loss of RF-MEMS switches, and can provoke self-biasing. This paper gives guidelines to avoid such false operation modes. The method can also be extended to yield the sensitivity of RF-MEMS devices to harmonic vibrations.