Bidirectional ferromagnetic spiral inductors using single deposition

RF VCO tuning using MEMS piezoelectric actuated variable inductors

“…This reduction in the tuning range and the inductance value can also be explained in terms of the change of the relative permeability l with the magnetic resonant frequency x FMR of the magnetic film. The relative permeability at dc conditions l dc is related to x FMR by [17,18]:…”

Soft magnetic materials application in the RF range

“…Performance of Q$10 at 1-2 GHz has been demonstrated for ferromagnetic spiral inductors (material: FeHfN [12], CoFeB [13], CoFeBN [14] or CoZrNb [15]). Discussions beyond the plain film material development itself include micro-fabrication process compatibility, in terms of stress and thermal stability [12], and availability of bidirectional easy axis orientations associated with the demagnetization and domain configuration.…”

“…Discussions beyond the plain film material development itself include micro-fabrication process compatibility, in terms of stress and thermal stability [12], and availability of bidirectional easy axis orientations associated with the demagnetization and domain configuration. The geometrical design of a patterned magnetic films against the coil legs, associated with the leakage flux and stray capacitance, should be included.…”

Quasi magnetic isotropy and microwave performance of FeCoB multilayer laminated by uniaxial anisotropic layers

“…It is required that the SMFs should have a well-defined in-plane uniaxial magnetic anisotropy (UMA) to reach a high ferromagnetic resonance frequency f FMR . [5][6][7] A high permeability is only available when excitation magnetic field being along the magnetic hard-axis (HA) direction, i.e., HA excitation. This restricts the efficiency of SFMs to 50% only for the uniaxial magnetic anisotropic SFMs.…”

“…Viala et al, proposed a rectangle inductor covered by a bidirectional solid-magnetic plane. 5 The solid-magnetic plane consists of four trapezoids, each of them covering a 1/4 surface of the spiral, and the easy axis of neighboring trapezoid subsequently rotates 90 , so that the easy axis of each trapezoid is parallel to the inductor lines. As a result, 100% HA excitation is realized.…”