Design, Simulation and Parametric Optimization of MEMS Based Varactor

This paper presents design, modeling and parametric optimization of RF MEMS varactor with large tuning range using electrostatic actuation. Optimized result is obtained using finite element method (FEM) and HFSS simulation to obtain large tuning ratio. Electrostatic torsion actuator is used in this model for actuation. The actuator beam transform the closing gap of torsion actuator into the movement of capacitor plate in the upward direction. The proposed design is optimized on the basis of electrode length ratio, levering ratio, gap between the plates. The design is demonstrated on 50 Ω coplanar transmission line for frequency range ofl-10 GHz, and optimized scattering parameters are achieved for both the actuated and un-actuated state. RF characteristics has been improved at electrode length ratio of 0.4404. Best performance is achieved at 5.5GHz with tunability of 157 % for Electrode length ratio of 0.4404.