A Novel Electrostatically Actuated High Q RF MEMS Tunable Capacitor for UHF Applications

A new wide tunability MEMS based variable capacitor using two separate electro-static vertical comb drive actuators

“…MEMS-based variable capacitors are used as key building blocks in many wireless communication applications, such as tunable filters, voltage-control oscillators, matching networks and phase shifters [1][2][3][4]. Commercially available solid-state varactors such as p-n junction diodes and Schottky diodes offer wide tuning range, small size and very fast tuning speed [5].…”

“…The movable plate can only be actuated one third of the initial gap distance; beyond this value, the two plates will snap together. This phenomena can be explained by the mechanical instability between electrostatic forces and restoring forces of the varactor structure, which causes the upper plate to snap down when it reaches one-third of the air gap [2,13]. In this case, the maximum theoretical tuning ratio is only 1.5:1.…”