Design of tunable interdigital capacitor

Abstract

In this paper, a MetalMUMPs (Multi-User Microelectromechanical System Processes) based tunable interdigitated capacitor is proposed. The tunable interdigitated capacitor consists of thermal actuator, guided beam, and twelve closely coupled parallel fingers lines to produce a nominal capacitance value of about 40.863 fF capable to tune till 326.902 fF. It actuated (tunned) thermally by applying a voltage across the thermal actuator to decreased distance between capacitor rotor and stator then capacitor becomes more capacitive, due to the increase in fringing fields between the fingers. The tunable interdigitated capacitor was fabricated on a standard low-resistivity substrate adopting MetalMUMPs manufacturing process. It was suspended by 25μm from the inner surface of the etched silicon substrate. It typical called microstrip tunable interdigitated capacitor. The capacitor was designed using 2008 CoventorWare software and fabricated based on MetalMUMPs technology. The measured capacitor structure is 494×520 μm2. The measured results show good compatible with theoretical one.