Simultaneous multi-mode analysis of surface acoustic wave device temperature stability utilizing time-frequency methods

Perturbations in the boundary conditions of Surface Acoustic Wave (SAW) devices are typically quantified through the use of frequency-domain methods, where the device is incorporated as the feedback element in a closed-loop oscillator. While simple in implementation, this method is inherently limited to tracking a single acoustic mode, and discards potentially useful information from the time-domain. In this work an alternative approach utilizing time-frequency methods to extract meaningful information from SAW device transient responses are considered. The advantages of the proposed method are experimentally demonstrated by varying the operating temperature of an XY-cut LiNbO₃ SAW device. The location in time and frequency of multiple acoustic modes was monitored simultaneously as temperature was varied between 30°C and 150°C. Data from the time-frequency domain demonstrates good agreement with conventional analysis techniques.