New orientations for bulk-acoustic-wave devices
01 Jan 1990-IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (IEEE)-Vol. 37, Iss: 3, pp 230-232
TL;DR: Several new materials/orientations for which strong BAW (bulk acoustic wave) response is predicted are presented and have much lower insertion losses and therefore present the possibility of superior BAW devices.
Abstract: Several new materials/orientations for which strong BAW (bulk acoustic wave) response is predicted are presented. These new materials/orientations have much lower insertion losses and therefore present the possibility of superior BAW devices. The results also point out some correspondence between pseudo-SAW and bulk acoustic waves. The pseudo-SAW waves cannot theoretically exist in a semiinfinite piezoelectric half-space. The presence of a pseudo-SAW pole with high coupling coefficient (related to the residue of the pole) indicates a strong bulk wave being launched into the medium. >
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TL;DR: In this paper, the substrate orientation and geometry are chosen correctly to design a clean plate mode response at a frequency up to at least six times that of the corresponding SAW device.
Abstract: If a SAW or SSBW device is operated above its normal frequency the interdigital transducers usually launch and receive a complex spectrum of plate modes. By contrast we show here that if the substrate orientation and geometry are chosen correctly it is possible to design a ‘clean’ plate mode response at a frequency up to at least six times that of the corresponding SAW device.
27 citations
TL;DR: In this article, the performance of a conventional pair of surface acoustic wave interdigital transducers (IDT) used to generate bulk acoustic waves is analyzed and closed-form expressions are derived for the important electrical and acoustical delay line characteristics and comparison is made with experimental measurements.
Abstract: Absrruct-The performance of a conventional pair of surface acoustic wave interdigital transducers (IDT’s) used to generate bulk acoustic waves is analyzed. An IDT located on the upper surface of a thick, rotated Ycut quartz crystal acts as the acoustic equivalent of an array antenna, launchingacollimated beam into the crystal bulk. The beam is reflected off the crystal bottom and redirected towards the upper crystal surface where it is intercepted by a second receiving IDT. Closed-form expressions are derived for the important electrical and acoustical delay line characteristics and comparison is made with experimental measurements. The analyzed characteristics of the reflected bulk wave (RBW) delay line are significantly different from either the SAW or SSBWand include a) a frequency bandwidth directly proportional to transducer length, b) a center frequency determined not by finger-to-finger spacing but rather by the ratio of transducer separation to crystal thickness, c) a nonresonant radiation resistance, d) the capability to synthesize filter designs in which the frequency response is proportional to the correlation of the individual transducer finger weightings, and e) the capability to modify temperature stability by change of transducer separation and crystal thickness. ULK ACOUSTIC wave radiation generated by interdigital B transducers has historically been considered as spurious, often degrading or interfering with the performance of devices based upon surface acoustic wave (SAW) excitation. Within the last several years, however, there has been increased interest in utilizing the bulk waves generated by IDT’s for practical microwave applications. Such surface-generated bulk waves make use of the IDT as an acoustic equivalent of a phasedarray antenna, with the electrode fingers constituting the array elements. The phasing between these elements is controlled by the applied signal frequency thereby allowing the direction of the acoustic beam radiated into the bulk to be scanned.
20 citations
TL;DR: In this article, the authors describe a transport d'energetic en mode de volume entre transducteurs interdigiteux sur un parallelepipede de LiNbO 3.
Abstract: Etude du transport d'energie en mode de volume entre transducteurs interdigiteux sur un parallelepipede de LiNbO 3 . Types de transport d'energie et trajectoires. Contribution aux proprietes finales de filtres a ondes de surface. Procede pour reduire et dans certains cas eliminer cette distorsion
10 citations
"New orientations for bulk-acoustic-..." refers methods in this paper
...To compare these devices with the BAW devices already known, we computed and found the insertion loss of these to be equal to 15.5 dB for FTF wave on 41 O Y rotated cut LiNbO, [3], 2 l dB for STL wave on (YXl) 128" LiNbO, [ 2 ] and 20 dB for STS wave on AC cut quartz [l]....
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01 Jan 1985
7 citations
TL;DR: In this paper, the authors present device responses due to fast shear and longitudinal waves, which propagate between a pair of IDTs on an upper surface via a reflection from the lower surface of a parallel-sided plate of 41°-rotated Y-cut lithium niobate.
Abstract: We present device responses due to fast shear and longitudinal waves, which propagate between a pair of IDTs on an upper surface via a reflection from the lower surface of a parallel-sided plate of 41°-rotated Y-cut lithium niobate. Single-mode response can be obtained by removing unwanted modes using saw cuts in the crystal substrate. Centre-frequency and bandwidth enhancement of a factor of two or more are achievable compared with the SAW response of the same IDTs.
5 citations