Lithium Niobate MEMS Chirp Compressors for Near Zero Power Wake-Up Radios

• Published in: Journal of microelectromechanical systems Vol. 26; no. 6; pp. 1204 - 1215
• Main Authors: Manzaneque, Tomas, Ruochen Lu, Yansong Yang, Songbin Gong
• Format: Journal Article
• Language: English
• Published: IEEE 01.12.2017
• Subjects: acoustic devices; Acoustics; chirp compressors; Chirp modulation; Compressors; delay lines; Internet of Things; Lithium niobate; low power devices; Low power electronics; Microelectromechanical systems; Micromechanical devices; Piezoelectric devices; piezoelectricity; Signal to noise ratio; wake-up radios
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2017.2750176

This paper presents the first demonstration of chirp compressors based on laterally vibrating modes in suspended lithium niobate thin films. Both shear-horizontal and length-extensional modes have been explored and demonstrated with the electromechanical coupling coefficients of 30% and 39%, respectively, in a double-dispersive delay line structure. The high electromechanical coupling, along with the low propagation loss in the suspended thin film, produces a low insertion loss of 10 dB over a large fractional bandwidth of 50%. The best fabricated device demonstrates a delay-bandwidth product of 100, and provides a voltage gain of 5 to the corresponding chirp signals. Moreover, significant signal-to-noise ratio enhancements (>100), collectively enabled by the processing gain and filtering characteristics of the chirp compressors, have been demonstrated. The measured devices, in this paper, greatly outperform state-of-the-art chirp compressors based on surface acoustic waves in insertion loss for a comparable TB. As a result, signal-to-noise ratio enhancement and voltage gain have been simultaneously demonstrated for the first time in a passive device and the analog domain. The high performance can be harnessed to greatly enhance the sensitivity of near zero power wake-up radio receivers and enable low-power wireless connectivity for Internet of Things applications.