RF MEMS fluidic variable inductor

Abstract

This paper presents a continuously variable inductor for Radiofrequency applications. The inductor is built using lamination of photosensitive films process. The variation principle is based on the change area of the loop inductor. The fluid moves between inter-spires distance and shortening the path length of the current through the structure; leading to reduction of the stored magnetic energy, and hence the inductance. A detailed electrical analysis is conducted to predict the tuning range of the inductor using simulation tools such as HFSS. At 3 GHz, the simulated inductor is continuously varied from 7 nH to 2.98 nH, i.e., the variable range is above 100%. The fact that the device is fabricated on glass process enhances the potential for system integration. The proposed variable inductor is perspective key component for the multi-band RF circuits such as electrically controllable matching circuits and wide tuning range voltage controlled oscillator (VCO).