A Core-Displacement Method Tunable Inductor using Micro-Electro-Mechanical-Systems Technology

In this paper, we introduce a new electrostatic tunable inductor with a simple tuning mechanism employing Micro-Electro-Mechanical-Systems. The proposed structure consists of a spiral inductor, a NiFe core material which is attached to a polysilicon support and electrodes of the electrostatic actuation. The inductance tuning mechanism is based on core-displacement and skin effect. When the electrostatic voltage is applied, the core is moved up and distance between the inductor and the core is increased, so magnetic stored energy of inductor is changed and hence the inductance tuning is achieved. The structure is simulated employing finite element method software such as COMSOL and ANSOFT HFSS. According to electromagnetic and electrostatic simulation results, a 69% tuning range at the frequency of 8 GHz and a quality factor of 13.3 has been achieved which is very suitable for RF applications. The simulation results show an electrostatic actuation voltage of the 25.3 V for the designed structure.