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Title: Multiphysics Challenges and Solutions for the Design of Heterogeneous Integrated Voltage Regulators
Committee:
Dr. Swaminathan, Advisor
Dr. Joshi, Chair
Dr. Smet
Abstract: The objective of the proposed research is to solve multi-physics challenges arising out of heterogeneous integration of voltage regulators. Integrated voltage regulators (IVRs) offer high power delivery performance and have become a recent trend in computing systems. However, the benefits of an IVR come at the cost of multi-physics design challenges. High voltage-conversion IVRs generally require embedding of passive components such as inductors in a package. For proper operation of the IVR, such package-embedded inductors need to meet multi-physics design considerations such as inductance, thermal resistance to ambient, saturation current, and size. However, the package-embedded inductors generally have either high inductance and low saturation current or vice versa. Besides, the embedded inductors suffer from Joule heating and magnetic core losses and have high thermal resistance to ambient, thereby reaching high temperatures and causing inefficient operation of the IVR. To solve these twin challenges of high temperature and a low saturation current of the package-embedded inductors, we present two novel solutions: dual-core coupled spirals and a glass micro-cooler. The dualcore topology sandwiches two spiral coils between the magnetic cores, thereby physically separating the cores. The separation between the cores acts as an air gap and increases the saturation current performance. The micro-cooler, on the other hand, allows a bi-directional heat flow for the inductors, which results in low thermal resistance to the ambient. The glass-based micro-cooler will be fabricated by first laser-patterning the micro-channels as blind cavities in a glass wafer, followed by sealing the channels with another glass wafer by anodic bonding. The electrical and thermal performances of the dual-core coupled inductors and micro-cooler will be characterized using a large-signal and thermal test chip (TTC) based test setups respectively.
