Sturcken, N.; O’Sullivan, E. J.; Wang, N.; Herget, P.; Webb, B. C.; Romankiw, L. T.; Petracca, M.; Davies, R.; Fontana, R. E.; Decad, G. M.; Kymissis, I.; Peterchev, A. V.; Carloni, L. P.; Gallagher, W. J.; Shepard, K. L. , A 2.5D Integrated Voltage Regulator Using Coupled-Magnetic-Core Inductors on Silicon Interposer, IEEE Journal of Solid-State Circuits, January, 2013
An integrated voltage regulator (IVR) is presented that uses custom fabricated thin-film magnetic power inductors. The inductors are fabricated on a silicon interposer and integrated with a multi-phase buck converter IC by 2.5D chip stacking. Several inductor design variations have been fabricated and tested. The best performance has been achieved with a set of eight coupled inductors that each occupies 0.245 mm2 and provides 12.5 nH with 270 mΩ DC. With early inductor prototypes, the IVR efficiency for a 1.8 V:1.0 V conversion ratio peaks at 71% with FEOL current density of 10.8 A/mm2 and inductor current density of 1.53 A/mm2 . At maximum load current, 69% conversion efficiency and 1.8 V:1.2 V conversion ratio the FEOL current density reaches 22.6 A/mm2 and inductor current density reaches 3.21 A/mm2 .