A Comparative Study on Insertion Loss Spectrum of Acoustic Delay Lines

In this work, two kinds of acoustic delay line (ADL) structures, up to 10 cells, are simulated and implemented on 400 nm suspended aluminum nitride (AlN) thin film, using double electrode (Double) and bottom floating (BF) single-phase unidirectional transducers (SPUDT), respectively. For fundamental symmetric (S0) Lamb waves, the insertion loss (IL) at the central frequency and the shape factor of these two SPUDTs are simulated using the finite element method (FEM) and calculated based on measurements, showing perfect matching in overall trend. The results demonstrate that increasing the number of cells can reduce the IL by 19.67 dB and improve shape factor by 0.179, at the cost of halving its bandwidth. These analyses pave the way for customized transmission line designs to meet various application requirements, particularly in on-chip signal transmission and computing.