Variable MEMS capacitors implemented into RF filter systems

A microelectromechanical systems analog tunable capacitor has been designed and fabricated for implementation into a two-pole UHF filter. Recent developments on the capacitor have improved the RF device performance significantly, and have resulted in improved UHF filter performance. In the 225-400-MHz range that this device is intended for, Q values are in excess of 100. In addition, an 8.4 : 1 tuning ratio has been achieved with continuous tuning over a 1.4 : 11.9-pF range. When implemented into a two-pole UHF filter, tuning over the entire 225-400-MHz range was achieved with a loss under 6.2 dB.