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Journal ArticleDOI

Theoretical analysis of planar bulk-acoustic-wave response

TL;DR: The theory is used to optimize one of these devices by varying the thickness and interdigital transducer (IDT) separation so as to give minimum insertion loss, and also to find a new BAW device with low insertion loss.
Abstract: A detailed theoretical analysis for planar bulk-acoustic-wave (BAW) devices that results in a method for computing the bulk-acoustic-wave response for any orientation of any piezoelectric substrate is presented. The BAW responses for four devices is computed and are found to be in excellent agreement with published experimental results. The theory is used to optimize one of these devices by varying the thickness and interdigital transducer (IDT) separation so as to give minimum insertion loss. A similar optimization can be performed for other devices. The theory is also used to find a new BAW device with low insertion loss. >
Citations
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Proceedings ArticleDOI
19 Mar 2007
TL;DR: A bias-tee has been developed with a voltage-independent capacitor, suitable for DC voltages up to 500 V showing excellent performance up to several gigahertz, and a calibration technique with applied bias significantly improves the measurement accuracy.
Abstract: During the AC impedance characterization of devices, from the kHz-range up to the GHz-range, accuracy can be lost when a DC voltage is applied. Commercial high-voltage broadband bias-tees are often voltage-dependent, which can cause inaccuracies at low frequencies. A calibration technique with applied bias significantly improves the measurement accuracy. Additionally, a bias-tee has been developed with a voltage-independent capacitor, suitable for DC voltages up to 500 V showing excellent performance up to several gigahertz. PIN diode limiters protect the measurement equipment from damage in case of a device breakdown.

15 citations

References
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Journal ArticleDOI
TL;DR: In this article, a method of analysis which uses a combination of analytical and numerical techniques has been developed to obtain an accurate solution to the coupled electromagnetic and acoustic fields set up by an interdigital transducer on the surface of a piezoelectric substrate.
Abstract: Ahrroct-A method of analysis which uses a combination of analytical and numerical techniques has been developed to obtain an accurate solution to the coupled electromagnetic and acoustic fields set up by an interdigital transducer on the surface of a piezoelectric substrate. Full account is taken of the coupling to bulk modes as well as surface modes, and the solution for the charge on the electrodes includes both electrostatic charge and piezoelectrically regenerated charge. Programs have been written for interdigital arrays with uniform aperture but varying electrode width and pitch and arbitrary electrical connections. The theory is also valid for arbitrary crystal orientations. Generation and detection may be analyzed separately with information being provided on the partition of power into the various acoustic modes and the external load impedance, and the bulk wave radiation patterns are also computed. The program may also be used to find the insertion loss of a pair of transducers. Results are presented for the BleusteinGulyaev orientation of PZT-4 ceramic and the YZ and 41” rotated YX orientations of lithium niobate.

339 citations

Journal ArticleDOI
TL;DR: In this paper, the surface and pseudosurface acoustic wave properties of berlinite (α•AlPO4) have been theoretically predicted in order to evaluate the merit of using this material in related surface acoustic wave devices.
Abstract: The surface and pseudosurface acoustic wave properties of berlinite (α‐AlPO4) have been theoretically predicted in order to evaluate the merit of using this material in related surface acoustic wave devices The surface and pseudosurface acoustic wave velocities, an estimate of the electromagnetic to acoustic coupling, the temperature coefficient of delay, the powerflow angle, and the attenuation have been determined for several standard crystallographic cuts These results supplement the results given by Carr and O’Connell This material is shown to possess several temperature‐compensated cuts and about four times the coupling of α‐quartz It is pointed out that α‐AlPO4 may be only one of many potentially temperature‐compensated materials with a silica derivative‐type structure

27 citations

Journal ArticleDOI
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

Journal ArticleDOI
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