Temperature-stable double SAW resonators

Area of Science:

• Materials Science
• Electrical Engineering
• Acoustics

Background:

• Surface Acoustic Wave (SAW) resonators on quartz exhibit temperature-dependent frequency shifts.
• First-order temperature coefficients of frequency (TCF1) impact device performance across temperature variations.
• Compensating second-order temperature coefficients of frequency (TCF2) is crucial for high-stability applications.

Purpose of the Study:

• To enhance the temperature stability of SAW resonators.
• To investigate methods for compensating both TCF1 and TCF2 in SAW double resonators.
• To present novel designs for temperature-stable SAW double resonators.

Main Methods:

• Utilizing double resonators with single resonator components having turnover temperatures above and below room temperature.
• Adjusting turnover temperatures via different propagation directions on ST-cut quartz.
• Developing and analyzing concepts for compensating TCF2 in one-port and two-port SAW double resonators.

Main Results:

• Achieved vanishing TCF1 in double resonators by positioning single resonator turnover temperatures strategically.
• Detailed two specific designs: a cascaded two-port resonator and a parallel one-port resonator configuration.
• Demonstrated frequency shifts below 20 ppm over a -30°C to 70°C temperature range for both designs using 35.5° rotY quartz.

Conclusions:

• Double resonator configurations effectively improve the temperature stability of SAW devices.
• The proposed methods successfully compensate for both first and second-order temperature effects.
• The developed temperature-stable SAW double resonators offer high performance within a wide temperature range.