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Title:Advancing acoustic filters for 5G front-ends: Lithium niobate piezoelectric MEMS resonators and filters
Author(s):Yang, Yansong
Director of Research:Gong, Songbin
Doctoral Committee Chair(s):Gong, Songbin
Doctoral Committee Member(s):Cunningham, Brian T.; Goddard, Lynford L.; Zhou, Jin
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):5G, front-ends, Mid-band, High-band, mmWave, MEMS, Acoustic, Resonators, Filters, lithium niobate,
Abstract:As the telecommunication industry moves towards 5G to support the increasing demand for broadband services, development of new front-end technologies is gaining steam to target higher performance at higher frequencies. A class of front-end components that have consistently received much research attention for 5G are the piezoelectric acoustic or MEMS resonators, filters, and multiplexers, as they remain essential for accessing the crowded RF spectrum with low loss, high interference rejection, and small form factors. This dissertation reports on the design, fabrication, and demonstration of a new class of microelectromechanical system (MEMS) resonators and filters operating in the 5G mid- and high-frequency bands. The 5G mid-band (Sub-6 GHz) resonances have been achieved by employing the first order asymmetric (A1) Lamb wave mode in the Z-cut and Y-cut lithium niobate (LiNbO3) thin films. The fabricated devices based on Z-cut LiNbO3 demonstrated an electromechanical coupling (kt2) of 30%, which is more than three times of current commercial solutions. The fabricated devices based on Y-cut LiNbO3 demonstrated a figure-of-merit (FoM) of 435, which is the highest in acoustic resonators over 1 GHz. The 5G mid-band devices marked the first time that a new resonator technology outperforms the state-of-the-arts. The 5G high-band (over-24 GHz) resonances have been demonstrated by employing the higher-order asymmetric Lamb wave modes in Z-cut LiNbO3 thin films, which marks the highest acoustic resonance in LiNbO3. The wide range of frequency operation and high performance of these A-modes devices have proven their potential as the key building blocks for future 5G front-end filters and multiplexers. Based on these breakthroughs, a new class of C-band and X-band acoustic filters is designed and demonstrated. The fabricated C-band acoustic filters demonstrated a 3-dB fractional bandwidth (FBW) of 10%, an insertion loss (IL) of 1.7 dB, an out-of-band (OoB) rejection of -13 dB, and a compact footprint of 0.36 mm2. The fabricated X-band acoustic filters demonstrated a 3-dB bandwidth of 70 MHz, an IL of 3.7 dB, and a compact footprint of 0.35 mm2. The work demonstrated in this dissertation show the strong potential of LiNbO3 A-modes filters for 5G RF front-ends.
Issue Date:2019-09-20
Rights Information:Copyright 2019 Yansong Yang
Date Available in IDEALS:2020-03-02
Date Deposited:2019-12

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