A Comparison of Temperature Performance of Saw Filters Made on ST- and LST-Cut Quartz

In 1985 Shimizu et al demonstrated that LST-cut quartz showed superior temperature stability over the regular ST-cut quartz when used in surface acoustic wave (SAW) devices. We built narrow band SAW bandpass filters centered at 200. 250. and 740 MHz on several orientations of LST- cut quartz. We also built ST-cut devices for direct comparison. In this paper we compare the temperature performance of the two types of SAW filters. We show that LST-cut devices show a greater increase in insertion loss as temperature rises as compared to the ST-cut devices. The applicability of LST-cut quartz for SAW devices is also discussed.