The tremendous growth of wireless devices and Internet of Things (IoT) applications has placed a great strain on the radio frequency (RF) network infrastructures, congesting the channels and over-crowding the radio frequency spectrum. Battery-operated portable smart devices such as smartphones, wearable technologies (e.g., smart watches and glasses), personal radars, and other smart gadgets all compete for bandwidth and require efficient spectrum utilization. To combat the looming RF spectrum scarcity, multi-band, multi-standard wireless systems that ?sense? the RF spectrum in response to the in-situ spectrum utilization, in the most efficient manner are required. Software solutions such as machine learning techniques are applied after the RF signal is digitized and often require large computational power. The machine learning techniques also face challenges of real-time learning and decision making to identify available channels in dynamical wireless environments. Signal processing and spectrum sensing at RF is a potential solution that can assist the software techniques and relax the receiver specifications. This CAREER project offers a transformative solution of RF spectrum sensing: a chip-scale multi-GHz nano-electro-mechanical frequency comb generator, integrated with other RF front-end electronics. This project aims to broaden the participation of K-12 and undergraduate students, particularly minority and female students, in STEM fields. The outreach plan will use educational kits and hands-on modules through collaboration with outreach programs at Georgia Tech.
At the heart of the spectrum sensor, the proposed compact RF comb generator, utilizes the parallel processing resulting from the multiple comb teeth to perform fast RF spectrum sensing, using lower power and fewer circuit components than the current state-of-the-art hardware solutions. The proposed nano-electro-mechanical frequency comb generator targets the super high frequency range (3-30 GHz) and harnesses new capabilities stemming from drastic reduction of piezoelectric film thickness in bulk acoustic wave resonators to generate wideband frequency combs. Leveraging their small size and high quality factor (Q), nanoscale acoustic resonators can be driven into the nonlinear regime, a prerequisite for comb generation, with very low input power. This CAREER project investigates the fundamental science behind the formation and tuning of multi-modal nano-electro-mechanical frequency combs, which remains under-explored to date. The study of nonlinear phonon interactions can elucidate fundamental physical phenomena, such as solitonic behavior, intrinsic localized modes, and chaotic behavior in such phononic systems.
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.
