Analysis of on-chip spiral inductors using the distributed capacitance model

The characteristics of on-chip inductors such as the S parameter, the quality factor (Q), and the self-resonant frequency (f_SR) can be determined by its series inductance, equivalent capacitance, and series resistance. In this paper, the distributed capacitance models have been developed to predict the equivalent capacitances of the on-chip spiral inductors such as planar and stacked inductor. Based on the equivalent capacitances formulas, a simple accurate methodology is proposed to build a compact model to predict the behaviors of on-chip inductors. A large amount of inductors have been implemented in 0.25-μm and 0.35-μm CMOS processes to demonstrate the prediction accuracy.