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

该项目响应了移动设备中对先进射频前端（RFFE）信号处理组件不断增长的需求，这是由不断扩大的无线连接环境所驱动的。5G/6G技术的迅猛发展凸显了在手持设备有限的空间和功率限制下集成更多RFFE元素的必要性，这需要低功耗的紧凑硬件。我们的总体愿景是通过开发更小尺寸、更高效率和更可调性的芯片级功能来简化RFFE的复杂性，并实现卓越的收发器。在RFFE组件中，压电声学微系统成为关键解决方案，具有比传统电磁（EM）同类产品小4个数量级的尺寸和更低的损耗。目前在6ghz以下频谱的RFFE滤波器解决方案中占主导地位，如果扩展到毫米波（mm-wave）频谱，这些微系统将有可能彻底改变信号处理。因此，克服与现有毫米波频谱声学平台和设备设计相关的长期挑战是本提案的主要目标。该项目更广泛的影响包括通过无线技术及其应用的创新带来的社会效益，以及旨在激励下一代科学家和工程师的教育推广活动。该项目致力于STEM教育，将研究与本科和研究生课程、学生指导和K-12学习模块紧密结合。本研究将与微波工程本科课程和微机电系统研究生课程紧密结合。通过网络研讨会活动的传播确保了广泛的影响，行业合作促进了射频声学研究成果的实际应用。我们的项目所实现的技术有可能显著降低耗电量大的RFFE的功耗，目前RFFE约占智能手机用电量的30%，有助于延长电池寿命，降低能耗，实现低碳经济。这个CAREER项目致力于推进微型压电声学设备，用于高效和自适应的RFFE信号处理，特别关注具有挑战性的毫米波频谱。该技术战略包括三个相互关联的研究重点，以解决当前技术的关键空白：1)毫米波低损耗声学平台的开发：利用高阶Lamb模式开发低损耗和宽带薄膜铌酸锂（LN）平台，以促进30 GHz以上的声换能器和波导的发展；2)射频声行波信号处理元件：采用图图化亚波长金属结构和LN薄膜上的压电换能器设计紧凑型行波RFFE信号处理元件，在保持低损耗的同时实现声学器件的小型化；3)自适应压电器件调谐：研究自适应压电器件的有效调谐机制，利用压电表面附近的静电驱动金属梁，提高器件性能，使其能够在动态无线环境中应用。所提出的声学微系统的紧凑尺寸和自适应能力将进一步推动无线收发器硬件小型化和低功耗预算。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.