A new wideband compact model for spiral inductors in RFICs

A new wide-band compact model for planar spiral inductors on lossy silicon substrate is presented. Transformer loops are used in the series branch of the equivalent circuit model to include the effects of the frequency-dependent losses, in particular eddy-current loss in the silicon substrate. The new compact model and the standard 9-element model are extracted from measurement data of a typical 1.5-nH spiral fabricated on a low-resistivity CMOS substrate over a frequency range of 0.1 to 10 GHz. The frequency-dependent series resistance and inductance as well as the quality factor obtained with the new model are in excellent agreement with the measured results.