STW two-port asynchronous resonator on BT-cut quartz.IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Nov; 55(11):2519-21.IT
A surface transverse wave (STW) 2-port asynchronous resonator on BT-cut (-50.5 degrees YX90 degrees) quartz was fabricated, measured, and calculated. At a frequency of about 332.4 MHz, insertion loss, and loaded and unloaded quality factors of about 11 dB, 8,000, and 11,500, respectively, were achieved. A turnover temperature of about 20 degrees C and a quadratic frequency-temperature coefficient of approximately -15 ppb/degrees C(2) were obtained. Compared with STW resonators on AT-cut quartz (36 degrees YX90 degrees), this temperature coefficient is about 4 times smaller, and about 2 times smaller than that for SAW on an ST cut. STW resonators and filters on BT-cut quartz can be used in applications requiring improved temperature stability.