Skin effect suppression for Cu/CoZrNb multilayered inductor

The Cu/Co ₈₅Zr ₃Nb ₁₂ multilayer is studied as a conductor of a spiral inductor to suppress the skin effect at the 5 GHz range (matches IEEE 802.11 a standard) using negative-permeability in CoZrNb films beyond the ferromagnetic resonance frequency. The skin effect suppression becomes remarkable when the thickness of Cu in each period of the multilayer, t _Cu, is less than the skin depth of Cu at the targeting frequency. For the 5 GHz operation, t _Cu ≤ 750 nm. The resistance of the Cu/CoZrNb multilayered spiral inductor decreases as much as 8.7, while keeping the same inductance of 1.1 nH as that of a similar air core. Accordingly, Q 16. Therefore, the proposed method can contribute to realize a high-Q spiral inductor. We also study the potentially applicable frequency of this method. Given a soft magnetic material with M _s 105 emu/cc and H _k = 5 Oe, the method can be applied at 700 MHz, the lowermost carrier frequency band for the 4th generation cellular phone system.