Design of coupled power inductors with crossed anisotropy magnetic core for integrated power conversion

Design and partial microfabrication of a coupled power inductor is presented for use in high power-density integrated voltage regulators (IVR). The proposed inductor uses many laminations of uniaxial, high-permeability magnetic material where the orientation of anisotropy between successive laminations is rotated to provide an effectively isotropic core. The high permeability core allows for an inductance density of 200nH/mm², while coupling between phases prevents magnetic saturation and allows a current density as high as 11A/mm² according to quasi-static finite-element-analysis (FEA) simulations. The coupling factor, inductance and resistance of the device are optimized for operation in a four-phase integrated buck converter switching at 100MHz.