Impact of In-Plane Diffraction in Temperature Compensated Surface Acoustic Wave Resonator on SiO₂/131°YX-LiNbO₃...

Area of Science:

• Materials Science
• Electrical Engineering
• Acoustics

Background:

• Temperature-compensated (TC) surface acoustic wave (SAW) resonators are crucial for stable frequency control.
• Understanding loss mechanisms is vital for optimizing resonator performance and quality factor (Q).

Purpose of the Study:

• To investigate the impact of in-plane SAW diffraction on the Bode Q factor in TC SAW resonators.
• To compare experimental results with theoretical models, specifically the full three-dimensional (3D) finite element method (FEM).

Main Methods:

• Utilized full 3D FEM simulations to model TC SAW resonator characteristics.
• Compared simulation results with experimental measurements, accounting for ohmic resistance.
• Investigated the influence of IDT finger pairs (N_I) and aperture length (W) on Bode Q.

Main Results:

• Full 3D FEM simulations closely matched experimental data for Bode Q, even without including additional loss.
• In-plane SAW diffraction was identified as a primary cause of loss in TC SAW devices.
• TC-SAW resonators exhibit more severe Bode Q degradation due to in-plane diffraction compared to I.H.P. SAW resonators.

Conclusions:

• In-plane SAW diffraction is a significant factor limiting the Bode Q in TC SAW resonators.
• The sensitivity of TC-SAW resonators to parameters like frequency (f), aperture length (W), and finger pairs (N_I) is higher due to their surface acoustic wave slowness shape.
• Full 3D FEM is a reliable tool for predicting and understanding these diffraction effects.