Wide-Band Acoustic Delay Lines Based on Dual Single-Phase Unidirectional Transducers

In this work, wide-band acoustic delay lines (ADLs) based on dual single-phase unidirectional transducers (SPUDTs) are simulated and implemented on 1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\ \mu \mathrm{m}$</tex> scan-dium doped aluminum nitride (Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</inf>Sc<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.3</inf>N) thin film. The band width (BW) of the ADLs was broadened by connecting two SPUDTs with adjacent passband in parallel to a single radio frequency (RF) port. The ADL based on the 7-cell dual SPUDT structure demonstrated a measured fractional band width (FBW) of 13.1%, representing an increase of 65.8% compared to the ADL based on single SPUDT, while maintaining nearly the same insertion loss (IL). Furthermore, a theoretical model of the phasor method was developed to explain the central passband fluctuation observed in the ADL with a 5-cell dual SPUDT configuration. This work not only broadened the ADL passband without increasing the IL but also holds significant importance for extending the operation BW of multi-physics coupled devices based on ADLs.