A novel high-Q inductor based on Si 3D MMIC technology and its application

A novel high-Q spiral inductor, implemented on a conductive Si wafer by applying a 3D MMIC structure over it, is proposed. The proposed inductor effectively uses a 10-/spl mu/m-thick polyimide layer and ground plane with a window below the spiral. A Q-factor of 21.7 at 1.88 nH and 5.8 GHz is achieved. A 5 GHz-band LNA is also designed with the new inductors and Si BJT with f/sub max/ of 24 GHz, and the highest-class of performance was predicted with a 20 dB gain and a 2.5 dB noise figure.