A high Q, large tuning range MEMS capacitor for RF filter systems

Using a new, double-sided adhesive process, an analog tunable capacitor has been designed and fabricated for implementation into a two-pole UHF filter. New design components such as two-sided metal deposition, low resistivity silicon, thicker device layers, and double beam suspensions have improved RF performance drastically. Additional improvements are demonstrated by critically damping the device in a liquid. In the 200-400 MHz range that this device is intended for, Q values are in excess of 100. In addition, an 8.4 to 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 a 225-400 MHz range was achieved with a loss under 6.2 dB. (C) 2003 Elsevier Science B.V. All rights reserved.