Analysis and modeling of thick-metal spiral inductors on silicon

In this paper, the analysis and modeling of thick-metal spiral inductors are addressed. The actual improvements of metal thickening in terms of quality factor are evaluated and related to skin and proximity effects. The inductance decrease due to metal thickening is also investigated and modeled using a modified current-sheet expression. The proposed formula achieves higher accuracy compared to the original one revealing errors below 5% even for thickness-to-width ratio up to 2.5.