Showing papers on "Interdigital transducer published in 1984"

New low-loss SAW filter using internal floating electrode reflection types of single-phase unidirectional transducer

Abstract: A new single-phase unidirectional transducer utilising the difference between excitation and reflection positions caused by the floating electrodes of open and short metal strips inserted into the interdigital transducer within a half wavelength is described.

Method of making a single phase unidirectional surface acoustic wave transducer

Abstract: A single-phase unidirectional surface acoustic wave transducer comprising a piezoelectric substrate and a transducer having localized symmetry and constructed for establishing a predetermined separation between the centers of acoustic wave reflection and transduction on said substrate by selectively orienting the transducer on a specific cut of said substrate to achieve a separation between said centers in a continuum of achievable phase angles of 0°-360 °.

Optical-gyroscope application of efficient crossed-channel acoustooptic devices

Abstract: An acoustooptic (AO) deflector/modulator using a single-mode crossed-channel waveguide of 2Δn type and an interdigital transducer is fabricated in aY-Z LiNbO3 substrate. This module has shown a high diffraction efficiency. A 50% diffraction efficiency and a bandwidth of 13.4 MHz were obtained with 0.13 W of surface-acoustic wave power centered at 320MHz. Since the cross section of the channel waveguide and that of the optical fiber are comparable, the interfacting of the resultant acoustooptic devices with fiber optical systems would greatly simplified. In addition, the frequency-shifted optical beam can be conveniently used as a reference signal or local oscillator in heterodyne detection. Consequently, this cross-channel acoustooptic device should find a variety of applications in realizing an integrated-optics module with a 50–50% power slit, optical communication, and an optical fiber system. One of those applications, optical gyroscopes, is proposed by using this kind of crossed-channel AO device.

Acoustic surface wave resonator device

Abstract: An acoustic surface wave resonator element has first and second interdigital electrodes consisting of pairs of opposed interleaving comb-shaped electrodes formed on one major surface of a piezoelectric substrate and arrayed along an acoustic wave propagation direction on the piezoelectric substrate, and acoustic surface wave reflectors sandwiching the first and second interdigital electrodes along the acoustic surface wave propagation direction. A base has the resonator element mounted thereon. First and second lead terminals are formed on the base and are electrically connected to the pair comb-shaped electrodes constituting the first interdigital electrode. A third lead terminal is electrically connected to one of the pair comb-shaped electrodes constituting the second interdigital electrode. The distance between the first and third lead terminals is substantially equal to that between the second and third lead terminals.

Slanted and chirped surface acoustic wave devices

Abstract: A surface acoustic wave device comprises a transducer 1 consisting of two electrodes 2 and 3 deposited on the surface of a substrate 4. Transducer 1 is a slanted chirped transducer with short fingers 5 and 6 to focus any acoustic wave generated in the transducer to a position along a line 8 spaced from transducer dependent on the frequency of the signal.

Gigahertz SAW Filters on YZ-Lithium Niobate Without the Use of Sub-Micron Line Widths

Abstract: Surface acoustic wave (SAW) filters operating in the gigahertz frequency range usually involve the use of interdigital transducers employing fingers and spacings with sub-micron geometries. This paper discusses the design of gigahertz SAW filters with much larger finger line widths and spacings in the order of 4 um on yz-lithium niobate; thereby allowing for the use of much simpler transducer fabrication techniques. The devices utilize stepped-finger interdigital transducer delay line configurations that operate efficiently in the 5th harmonic mode, and employ two electrodes per finger period. The transducers are designed to operate efficiently in the 5th harmonic mode by segmenting each electrode into five parts, and displacing each segment by a relative amount of wavelength at the funaamental frequency. /5 in terms of ho, the

A Novel Spectrum Analyser Based on the Slanted Chirped Transducer

Abstract: It has been shown that the Slanted Chirped Transducer (scp) launches surface wave8 (SAW) upon Y-cut lithium niobate that focus to a point and that the position of the focus is frequency dependent [I]. This paper reports the design, fabrication and assessment of a spectrum analyser in which the input is an SCP and the Output is an array of transducers positioned along the locus traced out by the focus as the frequency changes. Particular attention had been si6 to reducing the acoustic cross-tallc ( side-lobe levels) between channels employing techniques such a8 (i) weighting of the acoustic beam using the diffractive properties of the fingers, (ii) improving the focusing action by selecting a substrate orientation such that anisotropy compensated for the aberration p resent in the isotropic properties of an SCT and (iii) introducing frequency selectivity in the output transducer array. Experimental performance will be presented and compared with other spectrum analysers.

Non-destructive testing of semiconductors using acoustic wave method

Abstract: A contactless non-destructive technique for measuring at least one surface property of a first semiconductor material surface utilizes an electrically conductive interdigital transducer and a metal plate defined on a piezoelectric material. The metal plate has a window therein and the semiconductor material is positioned with its first surface over the window and facing the exposed piezoelectric material of the window. A radio frequency pulse is applied to the interdigital transducer to generate a surface acoustic wave on the piezoelectric material. This produces a transverse electric field which extends above the surface of the piezoelectric material and propagates across the window. This field acts as a probing field in the semiconductor material at the surface facing the piezoelectric material, and due to acousto-electric interaction a transverse acousto-electric voltage is produced. A dc voltage is applied to an opposite surface of the semiconductor to change the surface potential of the semiconductor material. A characteristic curve plotting the transverse acoustoelectric voltage against the dc voltage can be utilized to determine various surface properties for the semiconductor material. The window also defines the position where this surface property is measured.

Pyroelectric imaging of defects in bulk acoustic wave lithium niobate transducers

Abstract: Initial results on a method for testing piezoelectric transducers made of a polar material are presented. The method consists of measuring the voltage induced across the transducer electrodes by an intensity-modulated laser beam scanning the surface. Applied to a bulk acoustic wave LiNbO3 transducer, this technique has revealed domains with Z-axis reversed.

Surface acoustic wave infrared line imaging array

Abstract: A surface acoustic wave infrared line imaging array having a first interdigital transducer generating a first surface acoustic wave train amplitude modulated by the temperature profile of the substrate in response to a line segment of a received infrared image, a second interdigital transducer generating a parallel reference surface acoustic wave train, equal in amplitude but 180° out of phase with said first surface acoustic wave train, and a third interdigital transducer for summing the amplitudes of said first and reference surface acoustic wave trains to generate a wave train signal in which the individual waves are amplitude modulated in accordance with the intensity profile of the line segment of the infrared image received by the substrate underlying the first interdigital transducer.

Frequency fine adjusting method

Abstract: PURPOSE:To adjust simply the resonance frequency by adding a mass on the surface of a piezoelectric base. CONSTITUTION:Interdigital transducer electrodes are adhered on a piezoelectric base. The mass is added by using a mask 4 on which a face corresponding to a part where the surface wave on an SAW resonator or an SAW filter substrate is enclosed or propagated is opened. A metal is vapor-deposited by operating the SAW device and monitoring the frequency. As the mass to be added, a nonmetallic magnesium fluoride or quartz can be used. This method is applied to an SSBW having interdigital transducer electrodes, and a device utilizing Love, SH, Breustein-Gulyaev and Shimizu waves as well as the SAW device.

Electrode pattern for surface acoustic wave device

Abstract: A surface acoustic wave device comprises on a piezoelectric substrate a first interdigital electrode array for converting electric signals into surface acoustic waves and a second interdigital electrode array for receiving the surface acoustic waves propagating from the first interdigital electrode array along the surface portion of the piezoelectric substrate to convert them into electric signals again. The lengths of overlapping of the pairs of adjacent interdigital electrode or finger portions in each of the first and second electrode arrays are not the same. The distribution of the overlapping finger lengths in one of the first and second electrode arrays along the direction of propagation of the surface acoustic waves or the transverse direction of the piezoelectric substrate is such that the overlapping finger length has the minimum value at a central portion of the one electrode array and gradually increases toward both sides of the one electrode array.

Method and device for measuring non-electrical quantities

Abstract: The field of application is the measurement of non-electrical quantities such as pressure, temperature of gases and gas mixtures, forces, small distances or differences in travel in all fields of technology. It is the aim of the invention to create a method and a device which achieve high sensitivity, particularly in the area of very small changes, the production effort for which is small, which can be miniaturised and provide an easily exchangeable signal. According to the invention, the object is achieved by the fact that two interdigital transducers are applied to a piezoelectric substrate, one transducer being constructed as transmit transducer and the transmit signal itself being designed as coded signal, preferably binary phase keyed or linearly frequency modulated signal, and the second transducer being constructed as filter, preferably as matched filter. In this structure, designed as correlation filter, the autocorrelation function changes in a sensitive and easily measured manner when a non-electrical quantity acts on the interdigital transducer structure of the matched filter.

High speed receiver designs based on surface acoustic wave devices

Abstract: The principles of operation and several types of surface acoustic wave devices are reviewed. One device, the interdigital transducer device, can accomplish matched filtering for complex bandwidth-efficient phase modulations. Data speeds in excess of 120 Mb/s are accomplished with existing thin film lithography. Filters are cheap and small, and show little mismatch to the desired response. A number of receiver designs are proposed that are based on these filters. A bank-of-matched-filters approach seems superior to the Viterbi algorithm at high speeds.

Electrode structure of idt resonator or multimode filter provided with reflector

Abstract: PURPOSE:To simplify the production process and to prevent accidents such as a short-circuit, by connecting a required bus bar electrode of an IDT (interdigital transducer) resonator provided with a reflector to the reflector and supplying electric power through this reflector. CONSTITUTION:An IDT electrode 2 is provided on a piezoelectric substrate 1, and reflectors 3 and 4 are arranged on both sides of this electrode 2. One bus bar 5 out of bus bars 5 and 6 coupling IDT electrode fingers and one bus bar 8 out of bus bars 8 and 9 coupling a grating 7 of the reflector 4 are unified into one body, and electric power is supplied through the other bus bar 9 of the reflector 4. Since electric power is supplied to the bus bar 5 of the IDT through the reflector 4, its connection position to a lead terminal can be transferred to the same side as the lead terminal to the other bus bar 6, and a bonding wire is not stretched across the IDT.

Ultrasonic Array Transducer Using Interdigital Electrode

Abstract: A `planar array transducer' with interdigital electrodes is proposed. This paper describes the structure of the transducer and experimentally investigates its behavior and realization feasibility. A transducer directivity using PbTiO3 ceramics with a large electromechanical anisotropy shows the independent behavior of an array element that consists of a few electrode finger pairs. It was found that the array transducer could be realized without cutting by using the planar structure and also that the optimum pattern ratio R (the ratio of electrode finger width to period) is about 0.5.

A low-frequency resonator with interdigital electrodes

Abstract: A low-frequency resonator is described. The resonator, operating in a flexural mode, has interdigital electrodes on one surface of a thin piezoelectric ceramic plate. The interdigital electrodes are used as terminal electrodes of a one-port resonator as well as for poling treatment. The minimum impedance and its frequency are variable by changing the number of interdigital electrodes.

Preventing method of aging change in resonance frequency of piezoelectric device

Abstract: PURPOSE:To prevent the aging change in resonance frequency by vapor-depositing magnesium fluoride on the interdigital transducer electrode of a piezoelectric device or sticking surface between it and a reflector. CONSTITUTION:The interdigital transducer (IDT) electrode 2 is stuck to the surface of a piezoelectric substrate 1. Then, magnesium fluoride 9 is vapor- deposited on the IDT electrode 2 or the surface of the piezoelectric substrate where the reflector 3 is stuck to specific thickness. Therefore, the inclination of a decrease in resonance frequency considered as results from the condensation of an adhesive for fixing the piezoelectric substrate to a holder is canceled by the inclination of an increase in resonance frequency due to an aging change of vapor deposited magnesium fluoride.

Electrode structure of idt multimode filter provided with reflector

Abstract: PURPOSE:To reduce the loss of a filter and to facilitate the connection to an electrode lead, by increasing the width of a common bus bar of adjacent electrodes of the surface acoustic wave multimode filter toward both end parts without crossing reflectors and metal strips. CONSTITUTION:A common bus bar 7 of a pair of IDT (interdigital transducer) electrodes 5 and 6, whose number of pairs of electrode fingers is relatively small, formed on a piezoelectric substrate 1 is extended across reflectors 8 and 9 provided on both sides of electrodes 5 and 6 and has the width increased gradually toward outside parts of reflectors 8 and 9. When a bonding wire is stuck to the wider part of the bus bar also, the connection is facilitated, and the ohmic loss is small, and therefore, the loss of the filter is minimized.