Design and analysis of enhanced capacitive radio frequency MEMS switch based on Nb₂O₅ and HfO₂ dielectric for satellite payload applications

An innovative capacitive radio frequency MEMS shunt switch with a unique shaped spring is designed and analyzed using COMSOL Multiphysics 5.4. The proposed switch using Hafnium oxide (HfO₂) and Niobium pentoxide (Nb₂O₅) as the dielectric material between the transmission line and the deflecting gold membrane provides certain advantageous benefits with respect to performance parameters such as low actuation voltage, less spring constant, good isolation, low insertion loss, small size, and high capacitance ratio compared to other designs. A combination of three-turn meander and C- shaped spring having a spring constant of 0.186 N/m helps in achieving convenient actuation voltage. For 1, 1.5, and 2 μm air gaps, the actuation voltages required to bring the switch to ON mode are 1.77, 3.24, and 4.96 V respectively with Nb₂O₅ as the dielectric layer and 1.8, 3.28, and 5.01 V respectively with HfO₂ as the dielectric layer respectively. At 2-μm air gap, the capacitance ratio is 329 for Nb₂O₅ and 113 for HfO₂. RF analysis using ANSYS HFSS software shows the isolation of −19.41 dB at 11 GHz and insertion loss as low as −0.27 dB at 15 GHz. The proposed switch operating within the range of 1 to 30 GHz gives optimum results compared to other devices and is suitable for wireless communication and satellite payload applications.