Hao Wu, Michael Lekas, Ryan Davies, Kenneth L. Shepard Fellow, IEEE, and Noah Sturcken. Integrated Transformers With Magnetic Thin Films IEEE Transactions on Magnetics, Vol. 52, No. 7, July 2016

This paper presents the design and electrical performance of transformers with magnetic thin films for on-chip power conversion and isolation. The inductance of the devices is greatly enhanced by the use of a high-permeability magnetic material as a solenoid core, resulting in an inductance density of 108 nH/mm2. The total thickness of the transformer structures is <30 μm with a volume inductance density of 3.6 μH/mm3. By laminating the magnetic core, losses are well controlled leading to a peak quality factor (Q) of 16 at 40 MHz.