Simulation of the contribution of magnetic films on planar inductors characteristics

Abstract We propose here to use the interesting properties of magnetic thin films in order to improve planar inductors characteristics. Magnetic thin films serve as a way of confining electromagnetic field into the coil. Radio-frequency components require high-quality inductors. But at high frequencies several effects degrade the quality factor ( Q ) of the inductor. Our investigation deals with planar inductors, and we first try to optimize methodology of inductors design. The inductor area is kept constant (300×300 μm 2 ). Characteristics of spiral inductors heavily depend on coils structures (thickness, width, number of loops, shape …). The impact of spiral inductor parameters on the L and Q factors is studied. Q profit can reach 100% after coils parameters optimization. On the other hand, different designs with magnetic films are tested. The relative permeability ( μ r ) of magnetic material is set to 10 and dielectric/magnetic losses are assumed to be negligeable. Thicknesses of about 10 μm of magnetic material are reasonable in terms of technology and especially compatible with integration. At 2 GHz, with 10 μm under the coils, L and Q values have a profit of 44% and 9%, respectively compared to the non magnetic-structure. The results are based on RL model and are obtained from simulations (Ansoft HFSS) for frequencies up to 5 GHz.