Low Drive Voltage Shunt Capacitive Rf Mems Switch Design And Optimization

MEMS microwave switch is a new RF circuit component, which adopts MEMS technology. Comparing with traditional semiconductor switch, it has the merit of low insertion loss, high isolation and good linearity. It has practical significance to research on RF MEMS microwave switch for radar system and RF structure of communication system.This paper researched a capacitive shunt RF MEMS switch used in K-band and Ku-band, and used Ansys and Ansoft hfss to simulate the switch and optimize it's structures. The paper optimized its structures in order to reduce the actuation voltage in terms of promising the RF performance.First, this paper analyzed the working principle of a capacitive shunt RF MEMS switch and summarized the design points of the switch. On the foundation of further studying the influencing factors of CPW, CPW was designed and the characteristic impedance matched 50Ω. This paper established the mechanical model of the switch powered by the electrostatic forces and analyzed the elasticity coefficient of fixed-fixed beams. This paper compared four traditional switches and created a new structure switch. Then simulation and analysis on the electromechanical coupling model of the switch was performed; the fixed-fixed structure, tortuous beams and the holes were optimized. Through analyzing the fixed-fixed structure, this paper summarized the effect of several sizes on the deformation of the switch, rationally distributed the sizes of the fixed-fixed structure and optimized the structure. Through analyzing the tortuous beam, the paper summarized the effect of several sizes on the deformation and the structure was optimized hereby. Through analyzing the holes, it was believed that opening holes in the switch could affect the deformation and the basic rules of designing the holes were summarized. Finally, the paper performed full wave electromagnetic field analysis using the software Ansoft hfss and studied the effect of the dielectric layer on the RF performance of the switch. It is founded that using thin dielectric can improve the isolation and using the high dielectric constant material can improve the isolation in lower band.The properties of the switch are following: the switch's actuation voltage is 5.35V; one order frequency is 60500Hz. The typical shunt switch is excellent and capable of proving -0.05--0.2dB insertion loss and -20--42dB isolation in the frequency range 10-30GHz.