ECE PhD Proposal Review: Giuseppe Michetti

PhD Proposal Review: IoT Front-Ends enhanced by Time-Variant RF-MEMS based Circuits

Giuseppe Michetti

Location: Zoom

Abstract: Implementation of cheap, scalable radio frequency (RF) front ends in the context of the Internet of Things and 5G devices calls for reconfigurable and spectrally efficient components and circuits operating at RF. In the 4G era, micro-electro-mechanical systems (MEMS) based on piezoelectric resonators have dominated the filter market for mobile radios, due to their selectively narrow bandwidth (BW), small footprint, and for their capability to be mass-produced with standard CMOS techniques.
For succeeding in the 5G era, micro-acoustic technologies need to take on the challenge of large data-rates and potentially novel RF front-end architectures. To this end, I introduce spatio-temporal modulation as a powerful tool to enrich the state-of-the-art of RF front-ends, and I demonstrate how this can be effectively used to fundamentally increase the performance of high-quality factor microsystems operating at RF.
For the case of full-duplex systems, a nonreciprocal filter structure is proposed, together with its modeling, optimization strategies, and experimental demos at 1GHz and 2.5GHz. Starting from this novel modulation scheme, MEMS devices are used in place of other resonant technologies, to enable a filter that features strong nonreciprocal propagation at low power consumption (10s of uW) and high linearity (>30dBm).
For the case of half-duplex systems, a novel modulated filter architecture is introduced and modeled showing its capability of real-time BW control, as well as to fundamentally extend the BW limited of MEMS filters, typically associated with their limited piezoelectric coupling coefficient (k¬t2), without the need of lossy tunable components. Unprecedented BW tuning ratio (3:1) is experimentally demonstrated at VHF (300MHz) using commercial off-the-shelf resonators, within a compact footprint, large absolute BW, and at a reduced fabrication complexity.
To cast this device into next-generation mobile radios, custom-built MEMS devices are developed and characterized for these filter architectures. MEMS device designs for these architectures are proposed, leveraging the novel Sc- doped AlN thin-films technology recently added to the Northeastern portfolio of microfabrication capabilities.