Shallow Bulk Acoustic Wave Devices - A New Type of Acoustic Wave Device for Communication Systems

Abstract

This paper reviews the present status of a new type of acoustic wave device which has many potential applications. These devices are called Shallow Bulk Acoustic Wave (SBAW) devices because the signal propagates just below the surface of the piezoelectric substrate. These waves can be efficiently generated and detected by interdigital transducer and fabricated by techniques similar to those of surface acoustic wave (SAW) devices. These planar devices have been configured into bandpass filters, delay lines, oscillators and resonators. Because they utilize bulk waves rather than surface waves, SBAW devices possess many advantages over SAW devices. They have a higher frequency of operation, lower loss, better temperature stability, and, most likely, better aging characteristics. With these advantages, SBAW devices promise to replace both bulk crystals and SAW devices in many future communication systems.