Low-loss and wideband acoustic delay lines

Tomas Manzaneque, Ruochen Lu, Yansong Yang, Songbin Gong

Research output: Contribution to journalArticle

Abstract

This paper demonstrates low-loss acoustic delay lines (ADLs) based on shear-horizontal waves in thin-film LiNbO3 for the first time. Due to its high electromechanical coupling, the shear-horizontal mode is suited for producing devices with large bandwidths. Here, we show that shear-horizontal waves in LiNbO3 thin films are also excellent for implementing low-loss ADLs based on unidirectional transducers. The high acoustic reflections and large transducer unidirectionality induced by the mechanical loading of the electrodes on a LiNbO3 thin film provide a great tradeoff between delay line insertion loss and bandwidth. The directionality for two different types of unidirectional transducers has been characterized. Delay lines with variations in the key design parameters have been designed, fabricated, and measured. One of our fabricated devices has shown a group delay of 75 ns with an IL below 2 dB over a 3-dB bandwidth of 16 MHz centered at 160 MHz (fractional bandwidth = 10%). The measured insertion loss for other devices with longer delays and different numbers of transducer cells are analyzed, and the loss contributing factors and their possible mitigation are discussed.

Original languageEnglish (US)
Article number8671488
Pages (from-to)1379-1391
Number of pages13
JournalIEEE Transactions on Microwave Theory and Techniques
Volume67
Issue number4
DOIs
StatePublished - Apr 2019

Keywords

  • Acoustic devices
  • delay lines
  • lithium niobate (LiNbO3)
  • microelectromechanical systems
  • piezoelectric transducers
  • transversal filters

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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