Design strategy of on-chip inductors for highly integrated RF systems

This paper describes a physical model for spiral inductors on silicon which is suitable for circuit simulation and layout optimization. Key issues related to inductor modeling such as skin effect and silicon substrate loss are discussed. An effective ground shield is devised to reduce substrate loss and noise coupling. A practical design methodology based on the trade-off between the series resistance and oxide capacitance of an inductor is presented. This method is applied to optimize inductors in state-of-the-art processes with multilevel interconnects. The impact of interconnect scaling, copper metallization and low-K dielectric on the achievable inductor quality factor is studied.