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Dissertation Defense

Reconfigurable Bulk Acoustic Wave Resonators and Filters Employing Electric-field-induced Piezoelectricity and Negative Piezoelectricity for 5G

Milad Zolfagharloo Koohi


The ever-expanding wireless communications and sensing are influencing every aspect of human life. With the persistent demand for higher data capacity and recent advancements in wireless technologies, design of current radio frequency front-end circuitry in communication devices calls for transformative changes. Multifunctional materials, such as ferroelectrics and ferromagnetics, play an important role in providing critical solutions for communication, computation, and sensing. The integration of such materials into frequency-agile components promises reduced complexity, diminished size, and higher performance in 5th generation (5G) wireless technologies and beyond.

In this talk, reconfigurable ferroelectric-based radio frequency (RF) bulk acoustic wave (BAW) devices that facilitate efficient spectrum access for wireless technologies will be presented.

First, it will be described how the electrostriction phenomenon in thin-film barium strontium titanate (BST) is leveraged to develop the first intrinsically switchable BAW filter-bank, that eliminates the need for external solid-state switches, and significantly reduces the size, cost, and complexity of future radios. Next, it will be discussed how the electric-field-induced piezoelectricity and ‘negative’ piezoelectricity in multilayer ferroelectrics are exploited to overcome a fundamental frequency limitation of state-of-the-art piezoelectric BAW resonators. Such multilayer ferroelectric heterostructures provide a fundamentally new approach to synthesize the next generation acoustic wave devices that are programmable and have the capability to selectively operate across multiple frequency bands. Following this method, the first programmable BAW resonator and filter will be presented.

Chair: Professor Amir Mortazawi

Remote Access: https://umich.zoom.us/j/99134812893