High-performance micromachined RF planar inductors

High-Q planar spiral inductors were fabricated by innovative micromachining processes based on sputtered Al or electroplated Ag on top of low-loss substrates. 3 /spl mu/m-thick Al inductors on high-resistivity silicon (HRS) exhibited peak Q-factor of 30 at 5 GHz for corresponding inductance of 2.4 nH. A peak-Q of 70 at 3.8 GHz for 5.5 nH was obtained from a 10 /spl mu/m-thick Ag device on glass. Measured data were accurately matched using a new equivalent model based on frequency-independent elements. The fabricated inductors are suitable building-blocks for high-performance RF passive circuits, such as low-insertion loss filters and baluns.