Optimization of single-phase, unidirectional transducers using three fingers per period

Area of Science:

• Materials Science
• Electrical Engineering
• Acoustics

Background:

• Surface Acoustic Wave (SAW) filters are crucial for low-loss signal processing.
• Electrode Width Controlled (EWC) single-phase unidirectional transducers (SPUDT) are commonly employed in SAW filter design.
• Achieving both wide fractional bandwidth and low insertion loss simultaneously is a key challenge in SAW filter development.

Discussion:

• This study investigates the relationship between the geometrical configuration of EWC cells and their reflection and transduction coefficients.
• Simulations were performed on a 128 degrees Y-X lithium niobate (LiNbO3) substrate to analyze reflectivity.
• The impact of geometric parameters on the performance of EWC SPUDT cells was explored to enhance reflectivity.

Key Insights:

• Simulation results demonstrate that EWC SPUDT cells can achieve reflectivity exceeding 5% on a 128 degrees Y-X LiNbO3 substrate.
• Optimized EWC cell geometry is critical for improving the reflectivity of SPUDT transducers.
• Higher reflectivity directly correlates with the potential for achieving wider bandwidth and lower insertion loss.

Outlook:

• Fabrication of low-loss SPUDT test filters without weighting, utilizing the optimized EWC structure.
• Experimental verification of simulation predictions, with measured results validating the theoretical calculations.
• Potential for further advancements in SAW filter performance through precise control of EWC cell geometry.