Digitally controllable variable high-Q MEMS capacitor for RF applications

This paper describes the novel design of an electrostatic digitally controllable variable MEMS capacitor constructed using Cronos MUMPS technology and flip-chip technology processing. The capacitor consists of an array of individual plates of equal area, which are connected to the bonding pads by springs of varying width. This creates a cascading snap-down effect when actuated by electrostatic forces. The capacitor has a measured Q-factor of 140 at 750 MHz, and a tuning ratio of 4:1.