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High-Frequency Shallow Bulk Acoustic Wave Quartz Frequency Sources,
TRW ELECTRONIC SYSTEMS GROUP REDONDO BEACH CA
This paper describes the design and fabrication of high-frequency shallow bulk acoustic wave SBAW delay lines on quartz. Direct generation of frequency tones in the GHz range is desirable because it avoids the phase noise increase inherent in the multiplication of low frequency bulk-wave sources. The close-in phase noise can then be improved if desired by locking the GHz source with a bulk crystal. The devices reported in the paper used crystal cuts near AT because of its high velocity and BT because of its excellent temperature stability. Design parameters are chosen using an in-line model. This model uses the aperture width, number of fingers, wave velocity and coupling constant to predict radiation resistance, capacitance, and conversion loss. When used in conjunction with experimental propagation loss data, this model accurately predicts the total insertion loss of the device. Recent refinements of this model indicate that, at GHz frequencies, a significant trade-off exists between insertion loss and Q.
This article is from the Proceedings of the Annual Symposium on Frequency Control (37th), 1-3 Jun 83, Marriott Hotel, Philadelphia, Pennsylvania, AD-A136 673, p428-432.