New RF Magnetic Stripe Inductor with Flanges based on Exchange-Coupled Magnetic Films

A new type of RF-inductor on silicon is shown based on coplanar copper lines covered with a magnetic film. The realization features a new topology where the stripe is fully encapsulated with the film including flanges. It is also compared to three others configurations: top, bottom and sandwich. The realization is based on antiferromagnetic exchange-coupled CoFe films having a high natural ferromagnetic resonance frequency. As a best result, the closed inductor exhibit the highest linear density of inductance with 1.4 nH.mm^-1 and a quality factor of ~6 at 2.2 GHz. Measurements are compared with theoretical and simulation results, and also with more conventional inductors. We show for the first time a simple reversing differential method allowing full permeability measurements up to 20 GHz.