Analysis of modeling approaches for on-chip spiral inductors

The recent modeling approaches for on-chip spiral inductors are extensively investigated and compared. The key features of the models are detailedly analyzed. By actual implementation of each model's parameter extraction procedure, the pros and cons of equivalent circuit topologies, parameter extraction techniques, and fitting capacity of models are provided, including 1-π, 2-π, and T-models. 1-π models and T-models are proved to be adequate for modeling distributed effect. 2-π models are more convenient in fitting asymmetric inductors. The transfer function of the spiral inductor is employed in the singularity analysis of the models. The proposals are verified by measured the S-parameters of 10 fabricated CMOS spiral inductors up to 40 GHz.