GHz Low-Loss Acoustic RF Couplers in Lithium Niobate Thin Film

Ruochen Lu, Yansong Yang, Ming Huang Li, Songbin Gong

Research output: Contribution to journalArticlepeer-review

Abstract

We present the first group of GHz low-loss acoustic radio frequency (RF) couplers using the fundamental symmetric (S0) mode in X-cut lithium niobate thin films. The demonstrated multistrip couplers (MSCs) significantly surpass the insertion loss (IL) and the operating frequency of the previous works in more compact structures, thanks to the large electromechanical coupling and low loss of S0 in lithium niobate. The design space of S0 MSCs is first explored. Devices with different coupling factors are fabricated using different numbers of strips. Based on the S0 testbed with an IL of 4.5 dB at 1 GHz, the hybrid coupler shows an IL of 7.5 dB, while the track changer shows an IL of 5.1 dB, over a 3-dB fractional bandwidth of 8%. Couplers at different frequencies (between 0.75 and 1.55 GHz) are also investigated. Upon further optimizations, the S0 MSC platform can potentially enable low-loss wideband signal processing functions toward an RF acoustic component kit.

Original languageEnglish (US)
Article number8979176
Pages (from-to)1448-1461
Number of pages14
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume67
Issue number7
DOIs
StatePublished - Jul 2020

Keywords

  • Acoustic delay line (ADL)
  • S0 mode
  • directional coupler
  • lithium niobate
  • microelectromechanical systems
  • multistrip coupler (MSC)
  • piezoelectricity

ASJC Scopus subject areas

  • Instrumentation
  • Acoustics and Ultrasonics
  • Electrical and Electronic Engineering

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