Advancing acoustic filters for 5G front-ends: Lithium niobate piezoelectric MEMS resonators and filters

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2020

Author dc:creator

• Yang, Yansong

Contributors dc:contributor

• Gong, Songbin
• Cunningham, Brian T.
• Goddard, Lynford L.
• Zhou, Jin

• 5G, front-ends, Mid-band, High-band, mmWave, MEMS, Acoustic, Resonators, Filters, lithium niobate,

Statement dc:rights

• Copyright 2019 Yansong Yang

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/106316

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/106316