RF MEMs variable capacitors for tunable filters

An RF MEMs (microelectromechanical system) variable capacitor has been demonstrated with a 22:1 tuning range, tuning from 1.5 to 33.2 pF of capacitance. This capacitor was constructed using bistable MEMs membrane capacitors with individual tuning ranges of 70:1 to 100:1, control voltages in the 30–55 V range, switching speeds less than 10 μS, and operating frequencies as high as 40 GHz. These devices may eventually provide a viable alternative to electronic varactors with improved tuning range and lower loss.