Performance Enhancement of On-Chip Inductors With Permalloy Magnetic Rings

We demonstrate spiral inductors with continuous Permalloy ring structure at 100-μm scale, which achieve enhancements of sixfold in inductance and threefold in quality factor at frequencies as high as 200 MHz. The roll-off frequency is due to the eddy current loss in the conductive magnetic material. To reduce such loss and tune the permeability, the Permalloy film is laminated and split into bars. The dependence of the inductance and quality factor on permeability is further investigated. Different types of spiral inductors were fabricated with magnetic rings, helping shed light on optimization strategy.