A New Wide Tunability MEMS Based Variable Capacitor using Two Separate Electro-static Vertical Comb Drive Actuators

This paper presents a new MEMS variable capacitor to achieve high stable region and extremely wide tunability. The idea is based on increasing the stable region in the gap between the plates of the capacitor. It is done by combining the functionality of two different vertical comb drive actuator sets to takeover a unity air gap variation. The design of the structure is carried out so that the performance of these two actuator sets is fully independent without any destructive or damaging effect on each other. The advantage of this scheme is that adding the second mechanism of actuation does not change the overall structure thickness compared with when the structure uses a single actuation mechanism. Therefore, the tunability increases sharply. Aluminum is the structural material used for the design. Comb actuators are widely used as MEMS motors due to their long range of linear motion, low power consumption and ease of fabrication. A full review of electrostatic actuator portion is done. The structure is calculated using MATLAB software. To verify, the calculated results were compared with simulated results using Intellisuite software. The natural frequency is 1.173 KHz. According to calculation and simulation results the achieved minimum tuning range is 2300%.