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-mum and 0.35-mum CMOS processes to demonstrate the prediction accuracy.