A low voltage capacitive micromachined microwave switch

A novel capacitive micromachined microwave switch with low actuation voltage and stress is proposed. In this structure both plates of the switch act as a membrane. When actuation voltage is applied, upper plate moves down and lower plate moves up simultaneously, making the required contact. The displacement of each membrane in this structure is g₀/2 . Therefore because of the reduced displacement the stress is reduced. Actuation voltage of this structure by assuming equal spring constant of upper and lower membranes is thirty percent lower than the similar structures, with only single membrane and also maximum stress is reduced to half. Based on the S-N diagrams decreasing the stress and strain will increase the lifetime. The achieved results are due to only structural modification without losing any other parameters in the micromachined microwave switches, which is an advantage. The simulation results for structures with one and two membrane and with similar materials, geometry and with assuming no residual stress indicate that the actuation voltage is reduced from 17.5 V to 12.5 V in our proposed structure and the stress on the beam due to the actuation voltage is reduced from 0.319×10⁸ Pascal to the 0.16×10⁸ Pascal in our case.