CAREER: Radio Frequency Piezoelectric Acoustic Microsystems for Efficient and Adaptive Front-End Signal Processing

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This project responds to the escalating demand for advanced radio-frequency front-end (RFFE) signal processing components in mobile devices, driven by the ever-expanding landscape of wireless connectivity. The imperative to integrate more RFFE elements within the confined space and power constraints of handheld devices is underscored by the surge in 5G/6G technology, necessitating compact hardware with low power consumption. Our overarching vision is to simplify RFFE complexity and enable superior transceivers by developing chip-scale functionalities with smaller size, higher efficiency and more tunability. Among RFFE components, piezoelectric acoustic microsystems emerge as a key solution, boasting four orders of magnitude smaller sizes and lower losses than conventional electromagnetic (EM) counterparts. Currently dominating RFFE filter solutions in the sub-6-GHz spectrum, these microsystems hold the potential to revolutionize signal processing if extended into the millimeter-wave (mm-wave) spectrum. Hence, overcoming longstanding challenges related to existing acoustic platforms and device designs in mm-wave spectrum is the primary objective of this proposal. The project's broader impacts encompass societal benefits through innovations in wireless technologies and their applications, alongside educational outreach initiatives aimed at inspiring the next generation of scientists and engineers. Committed to STEM education, the project closely integrates research into undergraduate and graduate curricula, mentoring of students, and K-12 learning modules. The research will be closely integrated with undergraduate-level course of Microwave Engineering and graduate-level course of Microelectromechanical Systems. Dissemination through webinars events ensures wide-reaching impact, and industry collaboration fosters practical applications of research findings in RF acoustics. The technologies enabled by our project have the potential to significantly lower power consumption in the power-hungry RFFE, which presently accounts for approximately 30% of power usage in smartphones, contributing to longer battery life and lower energy consumption toward a low carbon economy.This CAREER project is dedicated to advancing miniature piezoelectric acoustic devices for efficient and adaptive RFFE signal processing, with a specific focus on the challenging mm-wave spectrum. The technical strategy comprises three interrelated research thrusts addressing critical gaps in current technologies: 1) development of mm-wave low-loss acoustic platforms: pioneering low-loss and wideband thin-film lithium niobate (LN) platforms leveraging higher-order Lamb modes to facilitate acoustic transducers and waveguides beyond 30 GHz; 2) RF acoustic traveling-wave signal processing components: designing compact traveling-wave RFFE signal processing elements using patterned sub-wavelength metallic structures and piezoelectric transducers on LN thin films, contributing to the miniaturization of acoustic devices whilst maintaining low loss; 3) adaptive piezoelectric device tuning: investigating an efficient tuning mechanism for adaptive piezoelectric devices, utilizing electrostatically actuated metallic beams near the piezoelectric surface, enhancing device performance, enabling applications in dynamic wireless environments. The proposed compact size and adaptivity of acoustic microsystems may drive further miniaturization of wireless transceiver hardware with lower power budget.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.