K-band lithium niobate microelectromechanical system hybrid filters
As the sub-6G spectrum becomes overcrowded with applications, the research community has begun to explore beyond 6 GHz for new spectral venues to advance wireless capabilities. Acoustic filters are indispensable front-end components in telecommunication, which is challenging to scale to higher frequencies. Frequency scaling without compromising performance remains challenging due to various technical bottlenecks in material integration, device fabrication, and filter design for acoustic filters. This thesis presents the design approach as well as the first demonstration of a wideband hybrid monolithic acoustic filter in the K-band, 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 Q in the acoustic domain. The performance trade space and design flow of the hybrid filter are also presented in this thesis, 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. The fabricated filter is built with the seventh-order antisymmetric Lamb wave mode (A7) resonators with an electromechanical coupling of 0.7%. The measurements show a 3 dB FBW of 2.4% at 19 GHz, and a compact footprint of 1.4 mm2.
microelectromechanical systems, millimeter-wave devices, piezoelectric devices, K-band
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign