Design and finite element modeling of series-shunt configuration based RF MEMS switch for high isolation operation in K–Ka band

Abstract

High isolation and low insertion loss is highly regarded for the devices designed for high frequency applications. A compact radio-frequency microelectromechanical systems switch on quartz substrate is presented in this paper. The high isolation is achieved by incorporating two membranes in series and shunt configuration on a single substrate while maintaining the compactness of the switch dimensions. The ohmic and capacitive switch membranes are designed in a cavity over co-planar waveguides on substrate. Spring constant, pull-in voltage, pressure distribution, squeeze film air damping, Q-factor, R, L and C for switch are calculated and analyzed by finite element modeler. Eigenfrequency analysis is also carried out using FEM to analyse the mode shape for first 6 eigenfrequencies. Biasing pads are provided on both ends of the switch for electrostatic actuation. Membranes with low spring constant are designed and optimized to work on same voltage level. Stress on membranes is analyzed and taken care of by the including meanders. This proposed switch is showing excellent isolation of $$75$$75 dB and low insertion loss of $$0.13$$0.13 dB at $$28$$28 GHz with need of actuation voltage of $$22.5$$22.5 V for both membranes in complete switch area of $$0.4$$0.4 mm$$^2$$2. The switch has wide bandwidth of $$30$$30 GHz from K and Ka band with above $$62$$62 dB of isolation.