Showing papers on "Interdigital transducer published in 2001"

Surface acoustic wave device, its manufacturing method, and circuit module using the same

Abstract: PROBLEM TO BE SOLVED: To obtain an SAW device which can be made smaller than the conventional types, and to provide its manufacturing method SOLUTION: A surface acoustic wave device is equipped with a piezoelectric board 11, a plurality of interdigital electrodes 12 arranged on the main surface 11a for exciting surface acoustic waves, a plurality of bumps 14 arranged on the main surface 11a, and an insulating sheet 15 arranged, so as to face the main surface 11a The bumps 14 and the interdigital electrodes 12 are electrically connected together, and the bumps 15 are provided penetrating through the insulating sheet 15

Optimized design and fabrication of a wireless pressure and temperature sensor unit based on SAW transponder technology

Abstract: The optimized design and fabrication of a passive pressure and temperature sensor unit based on SAW transponder technology fully meeting the restrictions of the European ISM RF band at 433.92 MHz is presented. The sensor unit consists of a reflective SAW delay line which is used as temperature sensor and transponder, and a capacitive pressure sensor. With a special arrangement of the impedance loaded splitfinger interdigital transducer, and the reference reflectors on the SAW substrate, a temperature corrected evaluation of the pressure signal is enabled. Due to the small dimensions and cost-effective design of the sensor unit, the utilization as a tire pressure sensor is proposed. A prototype of the SAW delay line and the micromachined pressure sensor is demonstrated.

Method of making composite piezoelectric transducer arrays

Abstract: Transducer elements having a 2—2 or 1-3 composite structure and driven in a k 31 transverse mode for small-feature size transducer arrays, which provide improved electrical impedance matching to an ultrasonic imaging system and improved acoustic matching to the human body. The transducer element includes a plurality of thin piezoceramic wafers which are electroded on opposing major surfaces. The spaced wafers are separated by a passive polymer layer in a composite structure. Methods of producing the transducer elements are also described.

Wireless communication system using surface acoustic wave (SAW) second harmonic techniques

Abstract: A system is for encoding information on a passive surface acoustic wave (SAW) device. The system includes a requesting unit configured to wirelessly transmit an impulse signal. The impulse signal is a signal that includes only a single pulse. A SAW device has an interdigital transducer (IDT) configured to physically store coded data. The SAW device is configured to receive the impulse signal. In response to receiving the impulse signal, the SAW device excites the IDT to generate a coded signal that includes the stored coded data and frequency components at a fundamental frequency.

Shear-horizontal acoustic waves in piezoelectric plates bordered with conductive liquid

Abstract: The influence of a conductive liquid on the characteristics of shear-horizontal acoustic waves of zeroth order (SH/sub 0/ mode) propagating in thin piezoelectric plates of lithium tantalate, lithium niobate, and potassium niobate was investigated. Experimental results obtained for SH/sub 0/ mode devices fabricated on lithium niobate plates are found to be in good agreement with theory. The data presented in this paper is useful for a proper design of various acoustic wave sensors operating in contact with conductive liquids.

Fundamental Study of a Stacked Lithium Niobate Transducer

Abstract: Generally, a lead zirconate titanate ceramic is utilized for a high-power transducer such as an ultrasonic motor drive. However, it is difficult to realize an ultrasonic motor that can withstand a high temperature, above 500°C. We focused on lithium niobate because it has a high Curie temperature (1210°C) and high quality factor. The electromechanical coupling factor of lithium niobate is large, although the permittivity is one hundred times smaller compared to that of hard-type lead zirconate titanate (PZT)-8. Hence a stacked structure is required to generate high output power. Dimensions of the fabricated actuator were 10 mm square and 18.5 mm long. The number of lithium niobate layers was 18. The calculated force factor of this transducer was 0.28 N/V, a value comparable to that of the bolted Langevin transducer using PZT, though the vibration velocity was saturated at 0.12 m/s. To realize improved transducer performance, we are attempting to fabricate a new transducer that can generate high vibration velocity.

Transducer and method for forming a transducer

Abstract: Transducer for converting mechanical stress into electric signals, which transducer is composed of at least one electromechanical sheet and is capable of converting mechanical stress into electric signals and in which transducer at least one of the electrodes required by the electromechanical sheet is disposed on the surface of one or more thin and flexible dielectric materials, said electrodes forming electrically conductive surfaces of the transducer for connecting the transducer to a signal processing device, and which transducer is constructed of a unitary, thin and flexible layered sheet structure and has the same width throughout its length.

Method of producing surface acoustic wave device

Abstract: A method of producing a surface acoustic wave device by use of a flip chip process, includes the steps of forming on a piezoelectric substrate at least one interdigital transducer and a plurality of electrode pads electrically connected to the interdigital transducer, forming bumps on the respective electrode pads, and providing an insulating film at a region other than a region where the bumps are formed.

Surface acoustic wave device, shear bulk wave transducer, and longitudinal bulk wave transducer

Abstract: A surface acoustic wave device includes a substrate and electrode disposed on the substrate. The electrode has a specific resistance ρ of up to about 1 Ω·cm and is made of a ZnO film with a low resistance having an impurity doping. A piezoelectric film having a specific resistance ρ of at least about 10 6 Ω·cm and a lattice constant within approximately ±20% of that of ZnO is disposed on the electrode. An interdigital electrode is disposed on the piezoelectric film.

Surface acoustic wave motor and apparatus having the same

Abstract: A surface acoustic wave motor with high energy efficiency, which may efficiently execute recovery of energy of surface acoustic waves propagated to the ends of piezoelectric substrate and re-excitation by the recovered energy. A comb-shaped electrode having interdigital structure for generating surface acoustic waves and two unidirectional comb-shaped electrodes having interdigital structure for recovering and re-exciting surface acoustic wave energy are arranged on a piezoelectric substrate, and a slider is disposed between the comb-shaped electrode for generating surface acoustic waves and the unidirectional comb-shaped electrodes for recovering and re-exciting surface acoustic wave energy. The surface acoustic wave generated by the comb-shaped electrode is recovered as an electric power by the unidirectional comb-shaped electrode arranged at one end of the piezoelectric substrate, and applied to the unidirectional comb-shaped electrode arranged at the other end thereof to re-excite the piezoelectric substrate.

A multi-resolution passive SAW chemical sensor

Abstract: Referring to the technology of SAW wireless identification systems, a passive SAW element for analyte sensing is developed. The sheet substrate is cut out of piezoelectric single crystal. One interdigital transducer (IDT) and several reflectors are manufactured on the surface of the substrate. When the sensing element is interrogated by a high-frequency modulated burst, the IDT transforms the signal into a SAW, which propagates on the surface of the substrate and is reflected by the reflectors. Thus, the information for the surface state is contained in the echoed wave. When the echoed wave is back to the IDT and transduced back into an electromagnetic signal, it can be received and processed by the interrogation unit. Therefore, when the surface is coated with analyte-sensitive film, a novel chemical SAW sensor can be implemented. Some attractive properties of the sensing system, which is quite different from the conventional SAW sensor, are theoretically predicted and experimentally verified.

Surface acoustic wave ladder filter with two series resonators having different apodization weighting

Abstract: A surface acoustic wave filter includes a piezoelectric substrate, and at least two series arm resonators and at least one parallel arm resonator each constituted by a one-port surface acoustic wave resonator, disposed on the piezoelectric substrate. The at least two series arm resonators and at least one parallel arm resonator are connected to define a ladder-type circuit. Each of the at least two series arm resonators includes an interdigital transducer weighted by apodization, and the apodizations for the at least two series arm resonators are different from each other.

Electrical and pyroelectric properties of in-plane polarized lead lanthanum titanate thin film

Abstract: Pb0.9La0.1Ti0.975O3 (PLT10) thin films were deposited on SiO2/Si(100) substrates coated with a ZrO2 buffer layer. Studies by x-ray diffraction and scanning electron microscopy reveal that the ZrO2 film consists of both tetragonal and monoclinic phases, with the tetragonal phase being the dominant one. The PLT10 film has a perovskite structure and the grains in the film have a rather uniform size of about 50 nm. By using interdigital transducer (IDT) electrodes the in-plane electrical properties, hysteresis loop, and pyroelectric coefficient of the PLT10 film were measured. The dielectric constant and loss factor vary only slightly with frequency in the range 103–106 Hz, with the loss factor being less than 0.01 over the entire range. The leakage current density is lower than 2×10−8 A/cm2 at a bias field of 5 kV/cm. The remnant polarization and coercive field are 12.6 μC/cm2 and 9.93 kV/cm, respectively. The film exhibits a reasonably high pyroelectric coefficient (95 μC/m2 K) after it has been poled by ap...

Ladder type surface acoustic wave filter

Abstract: PROBLEM TO BE SOLVED: To provide a ladder-type SAW filter, which has superior filter characteristic which oppresses a ripple within a passing band and is small in an insertion loss and an in-band deviation, in the ladder-type SAW filter. SOLUTION: A ladder-type surface accoustic wave filter employs a surface accoustic wave resonator. In the surface accoustic wave resonator, an interdigital transducer of an electrode cycle λand grating reflectors on both sides of the interdigital transducer are disposed along the propagation direction of a surface accoustic wave on a main surface of a piezoelectric substrate. With the arrangement of the ladder-type surface accoustic wave filter, ratio Lt/Lr of a pitch Lt of the interdigital transducer to a pitch Lr of the grating reflector is set to be smaller than 1, additionally a center-to-center distance Ltr between neighboring electrode fingers of the interdigital transducer and the grating reflector is set to be smaller than 0.5 λ, and further, Lts of the surface accoustic wave resonator of at least two or more from among a plurality of surface accoustic wave resonators which are disposed in a serial arm are made to differ from each other.

Acoustic surface wave resonator and filter therefor

Abstract: PROBLEM TO BE SOLVED: To provide an acoustic surface wave resonator which is of high-angle shoulder ratio and is wide in pass band width, and to provide an acoustic surface wave filter. SOLUTION: In the acoustic surface wave resonator which is constituted of at least one interdigital transducer made on a piezoelectric substrate, it is so arranged as to fulfill the relation of 0.15×L≤W≤0.45×L when defined that the total value of all electrode widths of the electrode digits constituting the above digital interdigital transducer is W, and that the length of the above interdigital transducer to the direction of propagation of the acoustic surface wave is L. COPYRIGHT: (C)2003,JPO

Surface acoustic wave filter and communication apparatus with the same

Abstract: A surface acoustic wave filter, has: a piezoelectric substrate; and at least two filter tracks having at least an input interdigital transducer electrode and an output interdigital transducer electrode provided on said piezoelectric substrate, wherein the respective input interdigital transducer electrodes of said at least two filter tracks are brought into connection in parallel; the respective output interdigital transducer electrodes of said at least two filter tracks are brought into connection in parallel, and overlapping widths of electrode fingers of said input interdigital transducer electrode and output interdigital transducer electrode are different from each other for each of said at least two filter tracks.

A multi-IDT input tunable surface acoustic wave filter

Abstract: Tunable surface acoustic wave (SAW) filters (TSF) have been widely used in the wireless telecommunication systems. A prototype of multi-IDT (interdigital transducer) input TSF has been developed. The device consists of 11 IDTs paralleled in the SAW propagation path. Different SAW filter configurations are realized by selecting or combining various IDTs, resulting in the tunability of both center frequency and 3 dB bandwidth. The center frequencies of the SAW filter range from 126.8 to 199.1 MHz; the 3 dB bandwidths range from 15.2 to 58.9 MHz. Impedance weighting methods have been applied. The passband ripple has been reduced from 6.44 to 1.37 dB after resistance weighting.

Hybrid MEMS-IDT-based accelerometer and gyroscope in a single chip

Abstract: In this paper, recent advances made on wireless MEMS-IDT (Interdigital Transducer) based accelerometers and gyroscopes at Penn State and HVS are presented. The concept and design principles are based on using surface acoustic waves (SAW) and polysilicon seismic mass for acceleration and proof mass for gyro. By designing the seismic mass of the accelerometer to float just above a high frequency Rayleigh Surface Acoustic Wave Sensor (SAWS), we are able to realize the accuracy and versatility required for the measurement of accelerations from 10 -6 g to 100g. The gyro design is based on the combination of Surface Acoustic Wave Resonator (SAWR) and Surface Acoustic Wave Sensor, which operates at the Rayleigh mode. The transmitter IDT creates SAW that propagates back and forth between the reflectors and forms a standing wave pattern within the cavity space between the IDTs. The particles at the anti-nodes of standing wave pattern experience large amplitude of vibration perpendicular to the plane of the substrate, which serves as the reference vibrating motion for the gyroscope. A number of metallic (proof) masses are strategically positioned at the anti-node locations so that the effect of the Coriolis force can be used to sense the gyroscopic motion.

The design of embedded transducers for structural health monitoring applications

Abstract: This paper describes a theoretical and experimental investigation concerning embedded piezoelectric transducers employed principally for condition monitoring of engineering composites. Both interdigital transducers (IDTs) and plate transducers are investigated with the aim of assessing their efficiency as uni-modal Lamb wave transmitters. The IDT configuration comprises a piezocomposite layer sandwiched between two flexible printed circuit boards, where the interdigital electrode spacing corresponds to the wavelength of the desired Lamb wave mode. The alternative configuration comprises a thin piezoceramic plate for which the lateral dimensions are chosen to efficiently couple energy into the desired mode. For both types of transducer, finite element models have been successfully employed to establish the design requirements for generating the zero order symmetrical mode (So) without simultaneously generating the zero order anti-symmetrical mode (Ao), which exhibits strong velocity dispersion. In this investigation the Ao mode is regarded as coherent noise. Generation of a pure So mode is shown to require positioning of the transducer at a depth which is exactly half way between the top and bottom faces of the plate-like structure within which it is embedded. For structural monitoring, the plate-type transducer is shown to be more suitable than the IDT. A scanning laser vibrometer was used to verify many of the theoretical findings.

Surface wave device, lateral wave transducer and longitudinal wave transducer, and manufacturing method for them

Abstract: PROBLEM TO BE SOLVED: To obtain a surface wave device that has a small insertion loss, a large electromechanical coupling coefficient (k) and an excellent conversion efficiency SOLUTION: This invention provides the surface wave device 1 where electrodes made of a low resistance ZnO film 13 formed by doping an impurity to ZnO whose specific resistivity ρ is 1 Ωcm or below are formed on a substrate 2, a piezoelectric film 14 whose specific resistivity ρ is 106 Ωcm or over and whose lattice constant is within ±20% of that of the ZnO is formed on the electrodes, and interdigital electrodes 15 are formed on the piezoelectric film 14 COPYRIGHT: (C)2002,JPO

Interdigital transducer with distibuted excitation

Abstract: An interdigital transducer for a surface acoustic wave includes an acoustic track with a width of BS ges and subtransducers arranged adjacent to each other on the acoustic track and connected in series. The subtransducers include, in a transverse direction, n series subtransducers each having a track width of BS xi (i=1, 2, . . . n(x); n (x)≧2). In the subtranducers BS ges = ∑ i = 1 n ⁢ ⁢ BS xi , BS xi does not equal BS (x+1)i .

Characteristic Analysis of SAW Filters Fabricated Using GaN Thin Films

Abstract: The surface morphology and characteristic parameters were analyzed for surface acoustic wave (SAW) filters, fabricated on epitaxially grown undoped GaN thin films on sapphire substrates. GaN thin films with good surface morphology (rms = 0.21 nm) were obtained. SAW filters with unapodized interdigital transducer/GaN./sapphire structure were used to estimate the characteristic parameters. The phase velocity and temperature coefficient of frequency (TCF) were 5550-4900 m/s and -60.8 to -50.0 ppm/°C in the temperature range between -25 and 50 °C at kh = 0.25-1.26, respectively. The fact that the temperature coefficient is even better at higher frequency explains that the SAW filters fabricated using GaN thin films would have a strong potential for GHz band applications.

AFM observation of surface acoustic waves emitted from single symmetric SAW transducers

Abstract: We report the first experimental observation of surface acoustic waves (SAWs) launched from a single symmetric SAW transducer, employing scanning acoustic force microscopy (SAFM). SAFM is a simple technique for the imaging of complex interdigital transducer (IDT) radiation patterns with nanometer lateral resolution. We demonstrate submicron lateral resolution and high sensitivity by investigating a single excitation element on a weakly coupling substrate (GaAs), visualizing the launched wave and second-order effects.

Surface acoustic wave device and piezoelectric substrate used therefor

Abstract: A compact and wide band surface acoustic wave device for intermediate-frequency is disclosed. A piezoelectric substrate for use in a surface acoustic wave device having high electromechanical coupling factor and low SAW velocity is also disclosed. The surface acoustic wave device is constituted of a piezoelectric substrate 1 and inter-digital electrodes 2, 2 formed on the piezoelectric substrate 1. The piezoelectric substrate 1 has a crystal structure of Ca3Ga2Ge4O14 and is represented by the chemical formula, Sr3NbGa3Si2O14. A cut angle of the piezoelectric substrate 1 cut out of the single crystal and a direction of propagation of surface acoustic waves on the piezoelectric substrate represented in terms of Euler's angles (φ, θ, ψ) are found in one of a first area represented by −5°≦φ≦15°, 0°≦θ≦180°, and −50°≦ψ≦50° and a second area represented by 15°≦φ≦30°, 0°≦θ≦180°, and −40°≦ψ≦40°.

Resonator-type saw filter with independent ground patterns for interdigital transducers and reflectors

Abstract: A resonator-type SAW filter has a ladder network of SAW resonators with respective interdigital transducers and reflectors. Individual ground patterns are provided for each interdigital transducer and each reflector in the shunt-arm SAW resonators. These ground patterns are electrically isolated from one another, and are grounded through separate bonding wires or other conductors that couple the ground patterns to a ground lead. This independent grounding scheme is found to improve the attenuation characteristic of the filter on the low side of the passband.

Ultrasound transducer and method for manufacturing an ultrasound transducer

Abstract: The ultrasound transducer (2) has a piezoelectric body (6), which has a number of transducer elements and a strip conductor foil (8) on a flat side (12), which has a conductive track pattern that determines the geometrical distribution of the transducer elements. Preferably, the geometrical distribution is a simple form, without any special structure. The film may be glued or mechanically pressed onto the piezoelectric body. An Independent claim is included for a method for manufacture the transducer.

Surface acoustic wave resonator and surface acoustic wave filter using the same

Abstract: PURPOSE: The surface acoustic wave resonator and surface acoustic wave filter using the same are provided, which realizes acoustic wave filter with higher angle ratio than conventional filters, by making the resonant frequency closer to the antiresonant frequency in a surface acoustic wave resonator. CONSTITUTION: The surface acoustic wave resonator comprises a piezoelectric substrate, a interdigital transducer part(2) formed on a piezoelectric substrate and composed of plural electrode fingers(3-4) having a period(pi) that is substantially equal to a wavelength of a surface acoustic wave to be excited, and at least one reflector(3-1,3-2) arranged in the vicinity of the interdigital transducer part(2) to reflect the surface acoustic wave excited by the interdigital transducer part in a direction parallel to a propagation direction of the surface acoustic wave. The interdigital transducer part(2) has three or more electrode fingers within the period(pi). The reflector(3-1,3-2) is composed of plural gratings having a period(pr) that is equal to a half of a wavelength of a surface acoustic wave propagating in the reflector.

Diffraction optical device and optical apparatus using the same

Abstract: An acoustooptic device is structured by providing an interdigital transducer in which arch-shaped electrode fingers are interdigitated so that the interdigital transducer is circular or annular in shape as a whole, on an optical waveguide which is circular when viewed from the front. This acoustooptic device is used as a diffraction optical device on which light is incident from the front. When an alternating voltage of a predetermined frequency is applied to the interdigital transducer by an oscillator, a concentric acoustic compressional wave is generated on the optical waveguide. The concentric acoustic compressional wave diffracts the incident light, so that the diffraction optical device functions like a lens and converges the luminous flux.

Surface acoustic wave filter with optimized width and pitch of interdigital electrodes and reflector electrodes

Abstract: A surface acoustic wave filter is free from any loss arising from the impedance mismatching by finding out optimum values achieving a widened band and lowered loss for the electrode width of the interdigital transducer and reflector electrodes. The surface acoustic wave filter includes interdigital transducers and reflectors arranged on both sides of the transducer. The piezoelectric substrate has a ratio h/λ of an electrode thickness h to a surface acoustic wave wavelength λ lying within the range of 0.05≦h/λ0.15 and has an electrode width ratio wr/pr of a reflector electrode width wr to an electrode pitch pr lying within the range of 0.5≦wr/pr≦0.6 and has an electrode width ratio wi/pi of an interdigital transducer interdigital electrode width wi to a pitch pi lying within the range of 0.6≦wi/pi≦0.9.

Rhombohedral-phase barium titanate as a piezoelectric transducer

Abstract: A piezoelectric transducer includes a barium-titanate-based piezoelectric material having a poled, rhombohedral structure. The rhombohedral barium titanate structure can include a dopant, such as KNbO3, BaHfO3, BaSnO3, BaZrO3 or KTaO3. The piezoelectric transducer can be used either as an actuator or as a sensor.