(she/her/hers)
University of Illinois at Urbana-Champaign
RF MEMS, Passive EM Devices, Wireless Communication
Liuqing Gao received the B.S. and M.S. degrees in electrical engineering in 2016 and 2020 from the University of Illinois at Urbana–Champaign, Urbana, IL, USA, where she is currently pursuing her Ph.D. She won the Best Student Paper Award at the 2020 IEEE International Ultrasonics Symposium, and 3rd place in Best Paper Competition at the 2020 IEEE International Microwave Symposium. She is also a recipient of the 2015 Omron Electrical Engineering Scholarship, the 2016 E. C. Jordan Awards, the 2016 Illinois Engineering Achievement Scholarship, the 2016 Highest Honors at Graduation, the 2017 ECE Distinguished Research Fellowship, the 2018 James M. Henderson Fellowship, the 2019 Dr. Ok Kyun Kim Fellowship, the 2020 John Bardeen Graduate Research Award, and the 2022 Mavis Future Faculty Fellowship from the Department of Electrical and Computer Engineering at UIUC. Her research interests include the design and microfabrication techniques of MEMS resonators, filters, and wireless communication systems.
Advancing Acoustic Devices Towards mmWave
As the sub-6GHz spectrum becomes over-crowded with applications, the research community starts to explore beyond 6 GHz for new spectral venues to advance wireless capabilities. Several bands ranging from 12 GHz to 27 GHz have been proposed, sharing the same challenge in scaling conventional front-end components well beyond their current operating frequencies. One indispensable front-end component that is particularly difficult to scale in frequency is the acoustic filters that have been commercially successful for 4G. Frequency scaling without compromising performance remains difficult due to various technical bottlenecks in material integration, device fabrication, and filter design for acoustic filters. My research focuses on the design approach as well as the demonstration of wideband hybrid monolithic acoustic filters at high frequencies beyond 14 GHz, which exceeds the limitation of electromechanical coupling on the fractional bandwidth (FBW) of acoustic filters. The hybrid filter utilizes the co-design of electromagnetic (EM) and acoustic to attain wide bandwidth while keeping the advantages of small size and high quality factor in the acoustic domain. The performance trade space and design flow of the hybrid filter are also carried out, which allows this technology to be applied for filters with different center frequencies and FBWs. The hybrid filter is simulated by hybridizing the EM and acoustic finite element analysis, which are carried out separately and combined at a system level. At high frequencies beyond 14 GHz, the influence of substrate loss on device performance becomes increasingly significant. By characterizing the loss in several commonly used oxide-on-Si substrates, a hybrid filter with improved performance due to reduced substrate loss has been demonstrated.