TWO NOVEL STRUCTURES FOR TUNABLE MEMS CAPACITOR WITH RF APPLICATIONS

—Two novel structures for high-Q MEMS tumble capacitors are presented.The proposed designs include full plate as well as the comb structured capacitors.They can be fabricated employing surface micromachining technology which is CMOS-compatible.The structures do not require the cantilever beams,which introduce considerable series resistance to the capacitor and decrease the quality factor.Therefore, our proposed structures achieve better Q in a smaller die area.The simulated results for 1 pF full plate capacitor shows a tuning range of 42% and a Q of 47 at 1 GHz.However, with the same initial capacitance, but the comb structure, the tuning range is increased to 43% but the Q is decreased to 45 at 1 GHz.The simulated Pull-in voltage with no residual stress is 3.5 V for both capacitors. The S11 responses are reported for a frequency range from 1 up to 4 GHz.