Showing papers on "Interdigital transducer published in 1971"
TL;DR: In this article, a normal mode expansion for the analysis of acoustic-wave problems is given, which is based on orthogonality relations between the modes of an acoustic wave, and makes it possible to relate the perturbation and propagation constant of a particular mode to the properties of the unperturbed system, and of perturbations.
Abstract: A normal mode expansion for the analysis of acoustic-wave problems is given. The expansion is based on orthogonality relations between the modes of an acoustic wave, and makes it possible to relate the perturbation and propagation constant of a particular mode to the properties of the modes of the unperturbed system, and of the perturbation. The use of the general expansions is then demonstrated by using it to determine a variational expression of an interdigital transducer. The results obtained are very similar to those of Smith, and demonstrate the connection between the crossed-field and series formulations for the transducer impedance.
101 citations
TL;DR: In this article, an acoustic surface-wave directional coupler is proposed that may be used on materials having a large electromechanical coupling constant to couple two acoustic beams which are many wavelengths wide.
Abstract: An acoustic-surface-wave directional coupler is proposed that may be used on materials having a large electromechanical coupling constant to couple two acoustic beams which are many wavelengths wide. The normal modes of the coupler are identified and used with an equivalent-circuit representation of the device to predict the length of the structure needed for complete energy transfer. The theory indicates that the device can have an intrinsic bandwidth near to 100%.
73 citations
Patent•
01 Oct 1971TL;DR: In this paper, a temperature compensated acoustic surface wave delay line is provided by the deposition of an interdigital electrode structure on a substrate with an overlay film surface of piezoelectric material of a predetermined thickness.
Abstract: A temperature compensated acoustic surface wave device, such as a surface wave delay line is provided in which temperature compensation is provided by the deposition of an interdigital electrode structure on a substrate with an overlay film surface of piezoelectric material of a predetermined thickness. A double substrate arrangement is also disclosed in which the interdigital electrode structure is deposited upon the surface of a non-piezoelectric layer which in turn is placed upon the surface of a piezoelectric substrate.
43 citations
TL;DR: In this paper, the acoustic surface wave launched by an interdigital transducer is experimentally shown to have a distorted wavefront when the transducers have varying finger overlap (apodization) and is on a high-coupling piezoelectric substrate, LiNbO3.
Abstract: The acoustic surface wave launched by an interdigital transducer is experimentally shown to have a distorted wavefront when the transducer has a varying finger overlap (apodization) and is on a high‐coupling piezoelectric substrate, LiNbO3. Results are shown for different transducer geometries, when an acoustic wave passes under the comb and when the apodized comb itself is driven. One geometry having extra metal fingers significantly reduces the wavefront distortion. The origin of the distortion is a retardation of the wave passing under metal fingers.
36 citations
TL;DR: In this article, an acoustic surface-wave multistrip coupler, formed into the shape of a U, was used on materials of high electro-mechanical coupling coefficient to convert a bidirectional interdigital transducer into a unidirectional transducers with negligible loss of bandwidth.
Abstract: An acoustic-surface-wave multistrip coupler, formed into the shape of a U, may be used on materials of high electro-mechanical coupling coefficient to convert a bidirectional interdigital transducer into a unidirectional transducer with negligible loss of bandwidth. The U-shaped coupler by itself acts as a normal-incidence mirror, and can have a reflection loss of less than 2 dB over a 60% bandwidth. Both devices are constructed of evaporated aluminium by existing photolithographic techiques. No special polishing operations or extra electrical components are required.
29 citations
TL;DR: A more accurate representation of an interdigital array is obtained by using an equivalent circuit intermediate between the crossed-field and in-line-field models, with negative capacitance, velocity, length and coupling dependent on the electrode-width/gap-between-electrodes ratio.
Abstract: A more accurate representation of an interdigital array is obtained by using an equivalent circuit intermediate between the crossed-field and in-line-field models, with negative capacitance, velocity, length and coupling dependent on the electrode-width/gap-between-electrodes ratio
20 citations
01 Jul 1971
TL;DR: In this article, the variational principle is used to analyse the behavior of an array of electrodes on a piezoelectric ceramic material for the generation of ultrasonic surface waves.
Abstract: The paper shows how the variational principle can be used to analyse the generation of ultrasonic surface waves by an infinite interdigital array of electrodes on the surface of a piezoelectric material. The method is used to analyse the behaviour of such an array deposited on a piezoelectric ceramic. Representation of surface-wave generation by an approximate electrical equivalent circuit is discussed, and the variation of piezoelectric coupling factor with the electrode width/gap ratio is computed for the fundamental resonant frequency, and the third and fifth harmonics. Bulk-wave generation is also treated in some detail.
14 citations
TL;DR: In this paper, the parametric interaction of surface-wave signals propagating in opposite directions on a lithium-niobate substrate has been used to obtain the crosscorrelation of digitally coded input signals.
Abstract: The parametric interaction of surface-wave signals propagating in opposite directions on a lithium-niobate substrate has been used to obtain the crosscorrelation of digitally coded input signals. The output 4 cm interdigital transducer was separated from the substrate by a 2000 A SiO2 layer to eliminate scattering into volume waves. Matched-filter responses for both amplitude-modulated and biphase Barker codes of up to 13 bits have been obtained.
12 citations
TL;DR: In this article, surface wave attenuation and reflection on closed paths have been observed on lithium niobate and quartz crystals and more than 12 circulations on a 25μsec quartz delay line have been achieved providing processing times in excess of 300 μsec.
Abstract: Surface waves circulating on closed paths have been observed on lithium niobate and quartz crystals. More than 12 circulations on a 25‐μsec quartz delay line have been achieved providing processing times in excess of 300 μsec. Surface‐wave attenuation and reflection which vary with the surface curvature are reported.
12 citations
Patent•
18 Oct 1971
TL;DR: In this article, a multiterminal acoustic surface wave transducer which has a unidirectional response characteristic over a selected operating frequency band and is capable of launching and receiving surface waves in a body of piezoelectric material is presented.
Abstract: Disclosed is a multiterminal acoustic surface wave transducer which has a unidirectional response characteristic over a selected operating frequency band and is capable of launching and receiving surface waves in a body of piezoelectric material. In a specific embodiment the transducer includes a plurality of sets of first, second and third parallel electrodes arranged in cascade on a surface of the piezoelectric material with a center-to-center electrode spacing equal to one-third wavelength of a selected frequency within the frequency band. Corresponding electrodes in each set are interconnected, with each group of interconnected electrodes forming a terminal of what is in this case a three terminal transducer. When a three phase electrical signal is supplied to the terminals of the transducer with a 120° phase separation between terminals, the transducer will launch a corresponding surface wave in the piezoelectric material in the direction of phase progression among the electrodes. Since the transducer is reciprocal in nature it can also be used to receive an acoustic surface wave propagating in a body of piezoelectric material and supply a corresponding electrical signal to a three phase load.
10 citations
01 Feb 1971
TL;DR: In this article, the authors used a model in which each electrode is represented by the ciruit of a bulk-wave transducer of width one-third of the spatial period of the array, which is used in studies of the continuous-wave radiation resistance of an array, the continuouswave voltage transfer from a generating array to a detecting array, and the detector waveform resulting from a transient generating voltage.
Abstract: Experimental and theoretical studies of the generation and detection of Rayleigh waves by arrays of interdigital electrodes deposited on piezoelectric ceramics are described. Experiments with transient voltages suggest that such a transducer can be represented by a 1-dimensional equivalent electrical circuit based on that conventionally used for a bulk-wave transducer, incorporating tranmission lines and piezoelectric transformers. More detailed studies lead to the adoption of a model in which each electrode is represented by the ciruit of a bulk-wave transducer of width one-third of the spatial period of the array. This circuit is used in studies of three important characteristics: the continuous-wave radiation resistance of an array, the continuous-wave voltage transfer from a generating array to a detecting array, and the detector waveform resulting from a transient generating voltage. The circuit is shown to be capable of dealing simultaneously with all three situations more accurately than circuits previously proposed.
TL;DR: In this article, experimental measurements of interdigital transducer input impedance are used to demonstrate that the coupling constant for piezoelectric surface waves can be enhanced by the use of an appropriate thickness dielectric overlay film.
Abstract: Experimental measurements of interdigital transducer input impedance are used to demonstrate that the coupling constant for piezoelectric surface waves can be enhanced by the use of an appropriate thickness dielectric overlay film. Measurements of the SiO2/YZ lithium niobate configuration are described and compared with an exact calculation and a qualitative perturbation analysis.
Patent•
23 Jul 1971TL;DR: In this paper, a transducer for exciting and/or detecting surface acoustic waves at both UHF and microwave frequencies in piezoelectric materials comprises a plurality of parallel spaced conductors deposited on the surface of the material.
Abstract: A transducer for exciting and/or detecting surface acoustic waves at both UHF and microwave frequencies in piezoelectric materials comprises a plurality of parallel spaced conductors deposited on the surface of the piezoelectric material.
Patent•
26 Jul 1971TL;DR: In this article, an interdigital transducer is formed on the piezoelectric material, and the end of the layer opposite one or both radiating directions of the transducers is tapered to reduce reflection of the surface wave as it propagates through the boundary between the polysilicon layer and the substrate.
Abstract: A structure for generating an acoustic surface wave in a non-piezoelectric substrate includes a thin layer of piezoelectric material over a portion of the substrate. An interdigital transducer is formed on the piezoelectric material, and the end of the layer opposite one or both radiating directions of the transducer is tapered to reduce reflection of the surface wave as it propagates through the boundary between the piezoelectric layer and the substrate. A waveguide structure having a tapered end is also described.
TL;DR: Theoretical predictions are made of the generation of Rayleigh waves and bulk waves by a single pair of electrodes on the surface of PZT 4, as electrode geometry and frequency vary as mentioned in this paper.
Abstract: Theoretical predictions are made of the generation of Rayleigh waves and bulk waves by a single pair of electrodes on the surface of PZT 4, as electrode geometry and frequency vary
TL;DR: In this paper, an interdigital surface-wave transducer with properties closely analogous to those of an electromagnetic quadrature hybrid junction is described, and the two electrical ports of such a hybrid-junction transducers are terminated in appropriate negative resistances.
Abstract: The letter describes an interdigital surface-wave transducer with properties closely analogous to those of an electromagnetic quadrature hybrid junction If the two electrical ports of such a hybrid-junction transducer are terminated in appropriate negative resistances, transmission gain is observed for an incident acoustic surface wave
Patent•
26 Apr 1971TL;DR: A SURFACE-WAVE ACOUSTIC DEVICE CHARACTERIZED by INPUT and OutPUT TRANSDUCERS DISPOSED on a SURFACE OF A PIEZOELECTRIC CERAMIC SUBSTRATE is described in this article.
Abstract: A SURFACE-WAVE ACOUSTIC DEVICE CHARACTERIZED BY INPUT AND OUTPUT TRANSDUCERS DISPOSED ON A SURFACE OF A PIEZOELECTRIC CERAMIC SUBSTRATE. EACH OF THE TRANSDUCERS IS OF AN INTERDIGITAL TYPE HAVING A PAIR OF COMB-LIKE ELECTRODES EACH OF WHICH HAS PRONG OR FINGER-LIKE ELECTRODES ARRANGED WITH THE FINGERS OR PRONGS OF ONE ELECTRODE DISPOSED BETWEEN THE PRONGS OR FINGERS OF THE OTHER ELECTRODES. THE DEVICE IS PRODUCED BY APPLYING A POLARIZING FIELD TO THE ELECTRODES TO CAUSE THE DIRECTION OF REMANENT POLARIZATION TO EXTEND FROM PRONG TO PRONG OF THE INTERENGAGED ELECTRODES OF EACH TRANSDUCER. THE DISTANCE OF THE PRONGS OF THE COMB-LIKE ELECTRODE FROM EACH OTHER IS EQUAL TO ONE WAVE LENGTH OF THE ACOUSTIC SURFACE WAVE.
IBM1
TL;DR: In this paper, a surface acoustic wave interdigital transducer designed to display enhanced response at harmonics of its fundamental operating frequency is described. But the performance of the transducers did not compare well with predictions based on a simple model.
Abstract: We describe a surface acoustic wave interdigital transducer designed to display enhanced response at harmonics of its fundamental operating frequency. The performance of the transducer compares well with predictions based on a simple model.
TL;DR: In this paper, an acoustic-surface-wave transversal filter for generation and processing of hyperbolic f.m. signals is described, which consists in linear modulating the spatial period of an interdigital array of tapping transducers on a piezoelectric substrate.
Abstract: The design of an acoustic-surface-wave transversal filter for generation and processing of hyperbolic f.m. signals is described. The synthesis procedure consists in linear-modulating the spatial period of an interdigital array of tapping transducers on a piezoelectric substrate. Two interdigital configurations have been designed, the first operating at the fundamental frequency, the other at the overtone mode which allows the use of the minimum number of transducers.
TL;DR: In this article, the properties of interdigital transducers have been used to construct a directional coupler, which consists basically of an array of eight transducers etched from an aluminium film deposited on a lithium-niobate substrate.
Abstract: The properties of interdigital transducers have been used to construct a directional coupler. The coupler consists basically of an array of eight transducers etched from an aluminium film deposited on a lithium-niobate substrate. Experimentally, a directivity of 17 dB was obtained at 75 MHz.
Patent•
10 Jun 1971
TL;DR: In this article, an acoustic surface wave parametric amplifier has an input interdigital pump transducer and an input intra-digital signal transducers formed on the surface of a piezoelectric material.
Abstract: An acoustic surface wave parametric amplifier has an input interdigital pump transducer and an input interdigital signal transducer formed on the surface of a piezoelectric material. A source of ac power is coupled to each transducer with the frequency of the source coupled to the signal transducer being lower than the frequency of the source coupled to the pump transducer. The ac source supplied to each of the input transducers creates an electric field in the piezoelectric material which is converted into an acoustic surface wave which propagates on the surface of the piezoelectric material. Preferably, the input transducers are oriented at an angle to one another so that the signal acoustic wave and the pump acoustic wave propagate at an angle to one another causing phase matching between the signal and pump waves. Interaction between the pump and signal waves causes amplification of the signal wave which is detected by an output interdigital transducer oriented parallel to and opposite the signal transducer. A dc voltage source may also be supplied between the signal transducer and the output transducer to compensate for the losses caused by the free carriers of the piezoelectric material.