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Showing papers on "Interdigital transducer published in 1973"


Journal ArticleDOI
TL;DR: In this paper, the authors used an interdigital electrode structure overlaid with a piezoelectric film for the excitation of surface acoustic waves on a non-piezolectric material.
Abstract: This paper is concerned with the theory of excitation of surface acoustic waves on a nonpiezoelectric material, by using an interdigital electrode structure overlaid with a piezoelectric film The impedance and capacity of such transducers have been worked out The results are given in terms of Δv/v, the perturbation in acoustic wave velocity when a perfect conductor is placed in the position of the transducer A computer program which calculates surface wave propagation on a layered medium consisting of a film on a substrate, with arbitrary elastic and piezoelectric properties for both media, has been used to determine Δv/v, and hence the coupling coefficients and radiation resistance of the interdigital transducer As a function of piezoelectric film thickness, two peaks in coupling are observed The results for the interdigital couplers are in quantitative agreement with experiments employing single‐crystal materials Data for experiments using sputtered piezoelectric films also give qualitative agreement with the theory If high‐quality crystalline layers are used, the theory suggests that interdigital couplers on nonpiezoelectric delay lines with properties comparable to or better than the present piezoelectric delay lines may be achievable

223 citations



Journal ArticleDOI
TL;DR: A set of computer programs have been developed for calculating the velocity of acoustic surface waves on a substrate with or without a film overlay where both the film and the substrate may be arbitrarily anisotropic and piezoelectric as mentioned in this paper.
Abstract: A set of computer programs has been developed for calculating the velocity of acoustic surface waves on a substrate with or without a film overlay where both the film and the substrate may be arbitrarily anisotropic and piezoelectric. Several examples of practical significance are presented. These include (i) propagation around the curved surface of a wrap‐around delay line, (ii) power flow angles for Rayleigh waves on LiNbO3 and Bi12GeO20 substrates, (iii) enhancement in the performance of an interdigital transducer due to the deposition of a film overlay (values of Δν/ν as large as 5.45% have been calculated), (iv) Δν/ν curves for piezoelectric films on nonpiezoelectric substrates.

43 citations


Patent
03 Dec 1973
TL;DR: In this article, a broadband surface wave acoustic transducer with unidirectional transduction characteristics is described, where the inter-digital electrodes are spaced in accordance with a repeating series (n + 1/4) lambda, n + 3/4 lambda, (n+ 1/ 4) lambda, n + 2/4 ) lambda, and n+ 3/ 4 ) lambda where n is an integer and lambda is an acoustic wavelength.
Abstract: The disclosure relates to a novel broadband surface wave acoustic transducer having unidirectional transduction characteristics and to surface wave acoustic devices employing the broadband unidirectional transducer. In the preferred embodiment, the transducer comprises an interdigital electrode arrangement having an electrically conductive common strip meandering through the interdigital spaces of the electrode arrangement. The interdigitally arranged electrodes are spaced in accordance with a repeating series (n + 1/4) lambda , (n + 3/4) lambda , (n + 1/4) lambda , (n + 3/4) lambda . . . , where n is an integer and lambda is an acoustic wavelength. The meandering strip provides a common terminal for the interdigital electrodes so that signals 90* out of phase may be applied between the electrodes and the common terminal.

26 citations


Patent
10 Aug 1973
TL;DR: In this article, a method for shaping the transducer impulse response was proposed, which involves removal of individual fingers or groups of fingers from selected portions of the transducers' transducers to reduce the amplitude of the impulse response in those regions from which fingers have been removed.
Abstract: Prior art methods for shaping the impulse response of a surface wave delay line interdigital transducer include finger width weighting and finger overlap weighting. The new method for shaping the transducer impulse response disclosed herein overcomes several objectional characteristics of the prior art methods. The new method involves removal of individual fingers or groups of fingers from selected portions of the transducer. The amplitude of the impulse response in those regions from which fingers have been removed is reduced below the value which it would have if no fingers had been removed. The method thus provides the capability to control the relative amplitudes of the impulse response along the length of the transducer.

16 citations


Journal ArticleDOI
TL;DR: Theoretical predictions of the generation of Rayleigh bulk-shear and bulk-longitudinal waves by interdigital transducers on y-cut z-propagating lithium niobate were made in this article.
Abstract: Theoretical predictions are made of the generation of Rayleigh bulk-shear and bulk-longitudinal waves by interdigital transducers on y-cut z-propagating lithium niobate. Frequency response and bulk-wave radiation patterns are compared with experimental evidence, and the proportions of input power converted to the three modes are shown as functions of both frequency and number of finger pairs.

13 citations


Journal ArticleDOI
TL;DR: In this paper, the relative intensity of the transducers first and second spatial harmonics and the number and type of acoustic modes generated establish the existence of acoustic generation by parametric periodic coupling.
Abstract: Acoustic radiation by interdigital transducers on yz LiNbO3 has been studied experimentally in the region of strong longitudinal bulk wave generation. The measured relative intensity of the transducer first and second spatial harmonics and the number and type of acoustic modes generated establish the existence of acoustic generation by parametric periodic coupling.

11 citations


Journal ArticleDOI
TL;DR: In this paper, conductance and signal measurements are presented for interdigital transducers on rotated Z-cut X-propagating lithium niobate material for Rayleigh wave generation.
Abstract: Conductance and signal measurements are presented for interdigital transducers on rotated Z‐cut X‐propagating lithium niobate. The +41.5° rotated cut is shown to be a superior one for Rayleigh wave generation compared to the conventional Y‐cut Z‐propagating material. It has a higher electromechanical coupling constant and noticeably greater freedom from bulk wave generation at least up to the third harmonic Rayleigh wave frequency.

10 citations


Journal ArticleDOI
TL;DR: In this article, an acoustic-surface-wave point source was obtained when an interdigital transducer with concentric curved fingers was used, and the direction of propagation of the surface-wave beam emitted by this transducers depends on the frequency.
Abstract: An acoustic-surface-wave point source is obtained when an interdigital transducer with concentric curved fingers is used. An array transducer composed of 80 point sources has been tested. The direction of propagation of the surface-wave beam emitted by this transducer depends on the frequency. A transmitting-array transducer and five receiving transducers are deposited on a quartz substrate. Each of these five outputs corresponds to a given frequency and delay prescribed by the positioning. At 12°, scanning was attained for a frequency variation of 7.6 MHz around a central frequency of about 60 MHz, corresponding to a delay variation of 18.2 μs.

9 citations


Patent
19 Mar 1973
TL;DR: In this article, a transducer device comprising a substrate capable of propagating an elastic wave on its surface is presented, where a resistive film is disposed generally centrally upon the substrate, the film having a grounded lead on one side of the film and an ungrounded lead on the other side.
Abstract: A transducer device comprising a substrate capable of propagating an elastic wave on its surface. A resistive film is disposed generally centrally upon the substrate, the film having a grounded lead on one side of the film and an ungrounded lead on the other side of the film. At least one active-channel transducer is disposed on the substrate, for processing a surface-elastic wave, each transducer comprising an input active-channel transducer, disposed on one side, the input side of the resistive film, and an output active-channel transducer, disposed on the other side, the output side, of the resistive film. A reference-channel transducer, also disposed on the substrate, comprises an input reference-channel transducer, disposed on the input side of the film, and connectable to a reference signal source, which causes an elastic surface wave to propagate across the substrate including the area occupied by the resistive film; and an output reference-channel transducer, having an output lead, and disposed on the output side of the film. The combination comprises a surface-wave transducer device which may be temperature-stabilized.

9 citations


Patent
04 Sep 1973
TL;DR: In this article, a thin quartz oscillator element including a substrate of quartz with a plurality of electrodes disposed on a major surface of the substrate and extending outwardly beyond one edge of the quartz substrate was constructed.
Abstract: A thin quartz oscillator element including a substrate of quartz with a plurality of electrodes disposed on a major surface of the substrate and extending outwardly beyond one edge of the substrate. Metallic bodies are disposed on the same surface of the substrate as the electrodes remote from the electrodes. The electrodes thicken in the region that extends beyond the edge of the substrate to a sufficient thickness to be thereby reinforced. Another electrode made as a metallic layer is built-up on the opposite major surface of the quartz substrate. To construct the quartz oscillator, an upper and a lower major surface of a quartz substrate are lapped. The substrate is mounted on a jig, and a metallic layer is deposited on a surface of the substrate and extending from one end thereof. The metallic layer is coated with photo-resist, the photo-resist is exposed to light through a mask, and the photoresist is then developed to remove unexposed photo-resist. Areas of the metallic layer unprotected by photo-resist are etched away to form the electrodes and the metallic body. The substrate is removed from the jig, cleaned of remaining photo-resist, and the surface bearing the electrode and metallic body is covered with a second mask. A gold metal layer is plated onto the metallic bodies and the electrodes to increase their thickness to a predetermined value to reinforce them. A lower electrode is built-up on the lower major surface of the quartz substrate in a similar manner but is not reinforced by the application of a gold layer.

Journal ArticleDOI
TL;DR: In this paper, high-resolution optical spectroscopy was used to study the growth of continuously excited surface acoustic waves under 15 and 25-fingerpair aluminum interdigital transducers on ycut zpropagating lithium niobate.
Abstract: High‐resolution optical spectroscopy was used to study the growth of continuously excited surface acoustic waves under 15‐ and 25‐finger‐pair aluminum interdigital transducers on y‐cut z‐propagating lithium niobate. The observed exponential growth of the surface wave with distance is in agreement with simple coupled‐mode theory. The coupling parameter leads to a direct evaluation of the effective electromechanical coupling constant K. For yz LiNbO3 a value of K2=0.030±0.003 was found.

Patent
Klerk J De1
30 Mar 1973
TL;DR: An interdigital shear transducer as discussed by the authors consists of a substrate to which a first pair of first and second electrode arrays are deposited, and a piezoelectric film is deposited over the electrodes of the first pair and the substrate.
Abstract: An interdigital shear transducer which includes a substrate to which a first pair of first and second electrode arrays is deposited. Each array includes n metalized conductive pads and a pair of electrodes for each pad. Except for the first and last pads of the first and second arrays, respectively, one electrode of each pair is common to a corresponding but adjacent pad of an opposite array. The first and last pad electrodes are independent. All electrodes are interdigitated between electrodes of an opposite array. A piezoelectric film is deposited over the electrodes of the first pair and the substrate. A second pair of identical first and second arrays is deposited so as to have conductive pads in common with the first pair and electrodes deposited on the film over like electrodes of the first pair.

Journal ArticleDOI
TL;DR: Theoretical predictions of the piezoelectric generation of Bleustein-Gulyaev and bulk-shear waves by interdigital transducers on p.z.t.-4 ceramic are made in this paper.
Abstract: Theoretical predictions are made of the piezoelectric generation of Bleustein–Gulyaev and bulk-shear waves by interdigital transducers on p.z.t.-4 ceramic. Variation with frequency and number of periods of each transducer is studied for both metallised and free-external-surface regions. Bulk-wave radiation patterns for the two sets of electrical boundary conditions are also studied.

Journal ArticleDOI
TL;DR: In this article, the authors measured the properties of leaky surface waves propagating on 41° and 64° rotated cuts of LiNbO3 both on the free surface and under metal.
Abstract: Measurements are reported of the properties of leaky surface waves propagating on 41° and 64° rotated cuts of LiNbO3 both on the free surface and under metal. Transducer and multistrip-coupler performance are consistent with piezo electric-coupling constants of 18° and 12%, respectively. Insertion-loss and spurious-signal-level results show that the interdigital transducer with few finger pairs is better matched to a metallised propagation path than to a free surface path for leaky waves.

Patent
26 Dec 1973
TL;DR: In this paper, a piezoelectric substrate is equipped with an input transducer and an output transducers, and a permanent electrostatic image of the acoustic wave induced at the surface of substrate is formed by a given high frequency signal applied at the input transducers by means of an electron beam (4), deflected toward the substrate so as to impinge on the zone covered by the acoustic waves.
Abstract: A piezoelectric substrate (1) exhibiting sufficient electric isolation is equipped at its both ends with an input transducer (2) and an output transducer (3). There is formed a permanent electrostatic image of the acoustic wave induced at the surface of substrate (1) by a given high frequency signal applied at the input transducer, by means of an electron beam (4), deflected toward the substrate so as to impinge on the the zone covered by the acoustic wave. Readout of this image is obtained by a second electron bombardment. Deflection of the beam (50) is achieved by means of a difference in potential applied between the electrode (5) and elements (60, 61, 62 . . . ). The device enables a train of signals applied at the input transducer to be addressed and coded.

Patent
Daniel M1
24 Jul 1973
TL;DR: In this article, an improved semiconductor surface wave transducer and method for improving the efficiency of a surface wave Transducer comprising a semiconductor substrate upon which is deposited a thin piezoelectric film which has been fabricated thereon at least one interdigital electrode grid is presented.
Abstract: An improved semiconductor surface wave transducer and method for improving the efficiency of a surface wave transducer comprising a semiconductor substrate upon which is deposited a thin piezoelectric film which has deposited or fabricated thereon at least one interdigital electrode grid The method comprises increasing the carrier concentration of the semiconductor substrate to provide at least a plane of electrical conductivity underlying the piezoelectric film and electrode grid having a resistivity of less than 10 ohms-cm at 20 DEG C

Patent
28 Dec 1973
TL;DR: In this article, a new technique for weighting acoustic surface wave filter interdigital transducers was proposed, in which transducer pads are first deposited on a substrate, a dielectric layer was deposited thereover and interdigital fingers had a variable and selectable area where they overlap the dielectrics to effectively vary the amount of capacitive coupling of each finger and resulting in an acoustic wave which was uniform across its beam width.
Abstract: A new technique for weighting acoustic surface wave filter interdigital transducers in which transducer pads are first deposited on a substrate, a dielectric layer deposited thereover and interdigital fingers deposited atop the dielectric layer with the fingers having a variable and selectable area where they overlap the dielectric to thereby effectively vary the amount of capacitive coupling of each finger and resulting in an acoustic wave which is uniform across its beam width.

Patent
28 Dec 1973
TL;DR: In this paper, an improved interdigital surface wave transducer which eliminates unwanted signals due to reflections to a degree sufficient to permit its use as a television band-pass filter was presented.
Abstract: An improved interdigital surface wave transducer which eliminates unwanted signals due to reflections to a degree sufficient to permit its use as a television band-pass filter. The reflectionless surface wave transducer is obtained by using a modified form of unidirectional transducer in which an interdigital transducer is placed in the center of a U-shaped multi-strip coupler with the transducer phased off center by a distance DELTA d so as to satisfy an equation which will result in zero reflections.


Journal ArticleDOI
R.S. Wagers1
TL;DR: In this article, a perturbation analysis is presented for the reduction in the coupling coefficient of an interdigital transducer that is spaced away from the surface of a piezoelectric substrate by a thin isotropic non-piezoeellectric dielectric film.
Abstract: A perturbation analysis is presented for the reduction in the coupling coefficient ΔV/V of an interdigital transducer that is spaced away from the surface of a piezoelectric substrate by a thin isotropic nonpiezoelectric dielectric film. The analysis shows that the static capacitance and coupling ΔV/V are reduced rapidly by the addition of thin dielectric films, while the series radiation resistance is relatively insensitive to film thickness for films less than approximately 0.03 wavelengths.

ReportDOI
01 Apr 1973
TL;DR: In this article, a new electron-beam image projection exposure technique, the "slit-lens", can be applied to the fabrication of high resolution interdigital patterns for use as high frequency surface acoustic wave transducers.
Abstract: : The research demonstrates that a new electron-beam image projection exposure technique, the 'slit-lens', can be applied to the fabrication of high resolution interdigital patterns for use as high frequency surface acoustic wave transducers. Further research efforts include the development of the ancillary thin-film techniques for making metallic patterns on piezoelectric substrates, and the design, fabrication, and electrical test of actual surface acoustic wave delay lines produced by the foregoing techniques.


01 Aug 1973
TL;DR: In this article, the authors describe the electron beam microfabrication, transducer and matching circuit design, and packaging and testing of 24 acoustic surface wave devices, including delay lines, filters and test structures.
Abstract: : The final report contains a description of the electron beam microfabrication, transducer and matching circuit design, and packaging and testing (in certain cases) of 24 acoustic surface wave devices, including delay lines, filters and test structures. Electrode widths were varies from 0.45 to 3.0 micrometers; electrodes per transducer ranged from 7 to 274; transducers per crystal went as high as 6; and the substrates included lithium niobate, lithium tantalate, bismuth germanium oxide and quartz. A major portion of this program was the design, fabrication and evaluation of a particular bandpass filter. A set of conclusions are presented with general applicability. (Author)