This paper presents the design and optimisation of three types of high Quality (Q) factor air suspended inductors (symmetric (a), symmetric (b) and circular), using micro-electro-mechanical systems (MEMS) technology, for 10GHz to 20GHz frequency band. The geometrical parameters of inductor topology, such as outer diameter, the width of metal traces, the thickness of the metal and the air gap, are used as design variables and their effects on the Q-factor and inductance are thoroughly analysed. The inductor has been designed on high resistivity Silicon-on-Sapphire (SOS) substrate in order to reduce the substrate loss and improve the Q factor. Results indicate that the proposed inductor topology (symmetric (a)) has highest Q-factor with peak Q-factor of 192 at 12GHz for a 1.13nH inductance.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.