Design and Simulation of Capacitive MEMS Switch for Ka Band Application

Vinay Bhatia,Punam Rattan,Kuldeep Sharma,Sukhdeep Kaur,Mohammed Abdella Kemal,Vishal Jagota,Vimal Shanmuganathan

doi:10.1155/2021/2021513

Abstract

In this paper, RF MEMS switch with capacitive contact is designed and analyzed for Ka band application. A fixed-fixed beam/meander configuration has been used to design the switch for frequency band 10 GHz to 40 GHz. Electromagnetic and electromechanical analysis of three-dimensional (3D) structure/design has been analyzed in multiple finite element method (FEM) based full-wave simulator (Coventorware and high-frequency structure simulator). A comparative study has also been carried out in this work. The high resistivity silicon substrate (tanδ=0.010,ρ>8 kΩ−cm,εr=11.8) with a thickness of675±25 μmhas been taken for switch realization. The designed structure shows an actuation voltage of around 9.2 V. Impedance matching for the switch structure is well below 20 dB, loss in upstate, i.e., insertion loss >0.5 dB, and isolation of >25 dB throughout the frequency band is observed for the aforesaid structure. Furthermore, to increase the RF parameters, AIN dielectric material has been used instead of SiO2 resulting in capacitance in downstate that increases hence improved the isolation. The proposed switch can be utilized in various potential applications such as any switching/tunable networks phased-array radar, reconfigurable antenna, RF phase shifter, mixer, biomedical, filter, and any transmitter/receiver (T/R) modules.

Highlights

The Micro-Electro-Mechanical-System (MEMS) is an agglomeration of submicron mechanical moving parts and electronics components/elements on a single module/chip [1]
RF MEMS capacitive shunt switch has a major role for designing in an advanced communication application
RF MEMS switches based on MEMS technology offer many advantageous over solid-state switches, for example, high isolation, low insertion loss, zero DC power consumption, low noise, more linearity, and used up to millimeter wave [2,3,4]

Summary

Introduction

The Micro-Electro-Mechanical-System (MEMS) is an agglomeration of submicron mechanical moving parts and electronics components/elements on a single module/chip [1]. In capacitive type contact MEMS switch, a dielectric layer is used between the top beam and bottom electrodes for isolation. Series switch utilizes metal-metal contact, while shunt switches are mostly capacitive in nature [9]. RF MEMS capacitive switch uses silicon nitride as dielectric layer due to its medium dielectric constant (εr = 7:5), which provides the isolation between both electrodes [16] Other dielectric material such as TiO2 (εr = 32), strontium titanate oxide (εr = 120 [16]), hafnium dioxide (HfO2, εr = 25 [17]), piezoelectric lead zirconate titanate (PZT, εr = 190 [18]), and aluminium nitride (AIN, εr = 9:8 [19]) can be utilized because of high dielectric constant in place of silicon nitride layer for impressive RF performance

Methods

Discussion

Conclusion