Investigation on Switching Structure Geometries and their Impact on Electromagnetic Response of RF-MEMS Capacitive Switch

Abstract

This paper explores the impact of various switching structure geometries on the RF performance of a shunt capacitive switch. The switch geometries have been analysed as an electrical model in order to develop an understanding of the effect of geometrical changes in terms of scattering (S) parameters which affects the RF response of the switch. A RF-MEMS capacitive switch is built into a finite element method (FEM) based RF tool and the effect of meandering, actuation area, and further dielectric thickness have been analysed in this work. It is investigated that with an increase in the number of meanders, switch resistance and inductance have increased and thus the isolation peak is shifted towards low frequencies compared to the design having a low number of meanders. The switch with a smaller central overlap area has a good on-state response compared to the design having more central overlap area. Furthermore, reduction of dielectric thickness affects unactuated state response by tuning isolation to lower frequencies with a wider range of under 20 dB response points. As a result of the understandings gained from analysed structural modifications, designers can optimize the RF performance of the capacitive shunt switch in the desired frequency range.