S-Parameter-Measurement-Based Broadband Characterization for Frequency-Variant Aperiodic SAW Devices

The physical characteristics of surface acoustic wave interdigital transducers (SAW IDTs) with aperiodic and irregular grating structures are investigated. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i>-parameters for various test SAW IDT devices fabricated on 42<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∘</sup>YX-LiTaO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>3</roman></sub> (piezoelectric substrate) are measured using a wafer-level de-embedding technique over a broad frequency band. Acoustic wave propagation model parameters for the physical behavior of aperiodic or asymmetric SAW IDT devices are determined in terms of frequency-variant and grating-layout-dependent parameters but are not constant. It is shown that numerical calculations based on the proposed technique have excellent agreement with experimental data.