Abstract: A reliable SAW device has excellent reflection and a small size, which is achieved by reducing the number of fingers defining reflectors, such that losses due to a large electromechanical coupling coefficient are small and the film thickness of electrodes has much less effect on frequencies of the device. In the SAW device having pluralities of first fingers and second fingers, disposed on a quartz substrate, constituting an IDT for exciting SH waves and reflectors for reflecting the SH waves, respectively, the first and second fingers made mainly from Al are disposed on the ST-cut 90° X-propagation quartz substrate with the Euler angles (0°, ?, 90°±2°), wherein the angle ? is within the range of about 110° to about 150°, and a normalized film thickness (H/?) of the fingers is within in the range of about 0.025 to about 0.135.

Abstract: A surface acoustic wave resonator includes a piezoelectric substrate, and a SAW resonator having an interdigital transducer. The interdigital transducer satisfies 0.15L?W?0.45L where W is the total of widths of all electrode fingers that form the interdigital transducer, and L is a length of the said interdigital transducer in a direction of SAW propagation.

Abstract: In a substrate in which a reflection coefficient ? of a surface acoustic wave per electrode is small, the invention obtains a Q value or a CI value level, which is equivalent to or higher than that of a related art product, at a device size which is equivalent to the related art product which addresses the problem that the size of a surface acoustic wave resonator becomes larger. A surface acoustic wave resonator includes one interdigital transducer to excite a surface acoustic wave in a propagation direction x on a piezoelectric plate and a pair of reflectors arranged on both sides thereof in the propagation direction. The interdigital transducer is divided into three regions. The electrode fingers of the interdigital transducer of each region are formed at a fixed pitch which differs within 2%. The surface acoustic wave resonator possesses a single peak response.

Abstract: The invention provides a longitudinal double-mode SAW filter that has a large reflection coefficient by the electrode conductors and having flat pass band characteristics. In the longitudinal double-mode SAW filter, nearly all of higher-order natural mode oscillation displacements A0, S1 and A1 are made present in the first and second interdigital transducer regions. An electrode finger phase weighting is formed to correspond to a BPSK sign where a phase sign changes into 0 or ? at a polarity-changing point on an electrode charge distribution function Q(x) that generates on the electrode due to natural modes of oscillation. A single pair of natural modes, which exist stationary in the direction X of propagation of the surface acoustic waves that are utilized, is selected. A symmetrical mode charge distribution (Q(x), ?Q(x)) and an obliquely symmetrical mode charge distribution (Q(x), Q(x)) are generated in order to correspond to the regions of IDT1 and IDT2.

Abstract: A branching filter package has a SAW filter chip housing area which houses a piezo electric base, on which a transmitting SAW filter and a receiving SAW filter having a different frequency passing band with each other, are formed, and an impedance matching circuit and a branching circuit for the transmitting SAW filter and the receiving SAW filter.

Abstract: A surface acoustic wave filter includes a piezoelectric substrate and a plurality of one-terminal-pair surface acoustic wave resonators, which are disposed on the piezoelectric substrate in a ladder pattern and each of which includes an IDT electrode having a pair of comb electrodes. The one-terminal-pair surface acoustic wave resonators disposed in a ladder pattern include series resonators, all of which are thinned. The electrode pitch of the IDT electrode of at least one of the series resonators is different from that of the IDT electrodes of the other series resonators.

Abstract: An assembly and method for array processing of hermetically sealed Surface Acoustic Wave (SAW) Devices employs a non-conductive material having an array of spaced cavities extending into the material for receiving a SAW die face down, in a flip-chip arrangement. Each cavity has a peripheral recess dimensioned to receive a lid for hermetically sealing the die within the cavity. Conductive paths are provided from the interior of the cavity to the surface of the array for providing an electrical contact with the SAW die. Individual SAW devices are then provided by cutting along separation lines between adjacent cavities after a plurality of die have been hermetically sealed within its cavity.

Abstract: Proposed is a SAW HF filter with reactance elements, which is particularly suitable for mobile radio. The filter is balanced on both sides, is electrically symmetric, and comprises a four-pole reactance series element, which can be formed from two two-pole pole reactance elements or from a four-pole reactance element, and a resonator. One bar of the respective reactance elements is connected to the input side of the filter, while the other bar is connected to the output side of the filter.

Abstract: For improving the adjacent channel selectivity of a resonator filter, reflectors of resonators are differently designed so that the minimums of the reflection functions of different reflectors of a resonator are shifted relative to one another and preferably compensate with the corresponding maximum of the respectively other reflection function. This reduces noise spikes at the low-frequency side of the pass-band of corresponding resonator filters and, thus, improves the adjacent channel selectivity.

Abstract: An edge reflection surface acoustic wave filter includes IDTs disposed on a top surface of a piezoelectric substrate, and surface acoustic waves of the Shear Horizontal type are reflected between opposite edges. At least one outermost electrode finger in the direction of propagation of surface acoustic waves on the side of at least one of the edges is removed. Accordingly, desired filter characteristics can readily be achieved without causing variations in filter characteristics, spurious components at frequencies lower than the passband are minimized, and selectivity is greatly improved.

Abstract: Very low passband ripple is provided in a wide bandwidth high frequency SAW FIR filter using slanted finger IDTs by one or more of three techniques: cancelling regenerated SAWs at parallel-connected input IDTs of two SAW filters which are similar except for a quarter-wavelength difference in spacing of the input and output IDTs, this difference varying with wavelength across the IDT aperture; shaping edges of shield electrodes to provide quarter-wavelength differences in, and hence cancellation of, SAWs reflected at the edges, the differences varying with wavelength across the IDT aperture; and making pairs of slanted shield electrodes symmetrical to compensate for refraction of SAWs by the shield electrodes.

Abstract: A surface acoustic wave filter includes a first reflector, a first IDT, a second IDT, a third IDT, and a second reflector arranged in that order on a piezoelectric substrate. The first IDT and the third IDT, connected in parallel, are together also connected to an unbalanced signal terminal. The second IDT includes two separate comb-like electrodes arranged in the direction of propagation of a surface acoustic wave, and electrically connected in series to each other at a serial junction. The comb-like electrodes are respectively connected to balanced signal terminals. The outermost electrode finger of the first IDT is connected to the unbalanced signal terminal, and the outermost electrode finger of the third IDT is grounded.

Abstract: A reflective grating (36) for a SAW filter (10) or resonator. The reflective grating (36) is formed by selectively dithering grating grid lines (38) with respect to a uniform spaced grid of M number of grid lines (38) per each N wavelength (?) of the grating (36) (N?/M), where ? is the wavelength of the center of the frequency band of interest, M and N are integers and M>N. M and N are selected so that the grating (36) does not have a net reflection when all of the grid lines (38) are uniformly spaced. By controlling the dithering pattern of the grid line in each sampling period of N?, any desired net distributed reflectivity from the grating can be implemented in both magnitude and phase.

Abstract: A dual track SAW reflector filter (150) including a first track (152) and a second track (154). The first track and the second track (152, 154) include an input transducer (156, 164), an output transducer (158, 166), first reflectors (160, 168) and second reflectors (162, 170). The reflectivity function of the first reflectors (160, 168) and the second reflectors (162, 170) are equal in magnitude and opposite in phase. The input transducers (156, 164) have the same polarity and the output transducers (158, 166) have opposite polarities. Surface acoustic waves produced by the input transducers (156, 164) and received directly by the output transducers (158, 166) are in phase and cancel at the output transducers (158, 166). Surface acoustic waves reflected by the reflectors (160, 162, 168 and 170) are in phase and add at the output transducers (158, 166).

Abstract: A SAW filter includes a plurality of IDTs arranged on substrate along a SAW propagation direction, and balanced signal terminals connected to an IDT. The SAW filter is a floating balanced type. The plurality of IDTs are arranged so as to provide a horizontally asymmetrical structure with respect to an imaginary axis that is positioned at the approximate center of the center IDT in the SAW propagation direction and which is substantially perpendicular to the SAW propagation direction. Thus, a SAW filter having filtering characteristics and a balance-to-unbalance conversion function is achieved with high balance between the balanced signal terminals.

Abstract: A reflective grating (18) having spaced grid lines (36) patterned on a piezoelectric substrate (12) for controlling the magnitude and phase of surface acoustic waves (28) in a reflective filter (10) or resonator. The magnitude and phase of the surface acoustic wave (28) are controlled by a sampling period (34) of the reflective grating (18) and the density and sequence of distributed acoustic reflective dots (42). The reflective dots (42) are randomly distributed within gaps (40) between adjacent grid lines (36) or on top of the grid lines (36) of the reflective grating (18). The pattern of the reflective dots distributed within the gaps (40) or on the grid lines (36) is determined by the dot density, where the dot density varies from a lowest density of 0 to a maximum density of 1.

Abstract: A method and apparatus for enabling a mixed initiative dialog to be carried out between a user and a machine are described. A speech-enabled processing system receives an utterance from the user, and the utterance is recognized by an automatic speech recognizer using a set of statistical language models. Prior to parsing the utterance, a dialog manager uses a semantic frame to identify the set of all slots potentially associated with the current task and then retrieves a corresponding grammar for each of the identified slots from an associated reusable dialog component. A natural language parser then parses the utterance using the recognized speech and all of the retrieved grammars. The dialog manager then identifies any slot which remains unfilled after parsing and causes a prompt to be played to the user for information to fill the unfilled slot. Dependencies and constraints may be associated with particular slots.

Abstract: A longitudinally-coupled resonator surface acoustic wave (SAW) filter includes a piezoelectric substrate and at least two IDTs arranged in the direction along which a SAW propagates on the piezoelectric substrate. At least one of the IDTs has an electrode finger wherein the metallization ratio of the electrode finger is different from that of the other electrode fingers of the IDT.

Abstract: A dual mode SAW filter is provided with improved symmetry and/or blocking attenuation by selecting the structure in one-track, two-track embodiment and with potentially split track, in which first transducers and second transducers, these as input transducers and/or output transducers and/or coupling transducers (given a multi-track embodiment), always have an even-numbered plurality of fingers and are point-symmetrical.

Abstract: A cascaded SAW filter system includes first and second SAW filters (12a, 12b) each including an input transducer (36, 36′) and an output transducer (37, 37′) on a piezoelectric substrate (38, 38′). Group delay and pass band ripples associated with a time spur at TD′ away from the main signal of the second filter (12b) cancel the group delay and pass band ripples associated with a time spur at TD away from the main signal of the first filter (12a) because: 1) the input and output transducers (36′, 37′) of the second filter (12a) are offset from those of the first filter (12a); 2) the center frequency (f0′) of the second filter (12b) is offset from the center frequency (f0) of the first filter (12a); 3) the perturbation region (P1) of the first filter (12a) is different from the perturbation region (P2) of the second filter (12b) or 3) a combination of 1), 2) and/or 3. The associated time spur echo of the cascaded response will also be canceled.

Abstract: In a longitudinally coupled multi-mode surface acoustic wave filter which has an assembly of more than two interdigital transducers formed on a piezoelectric substrate and reflectors composed of shorted grating electrodes different in pitch from the IDTs. The grating electrodes are weighted so that their numbers vary linearly with the position in the direction perpendicular to the direction of propagation of surface acoustic waves.

Abstract: A method of manufacturing an edge reflection type surface acoustic wave device includes the step of preparing a surface acoustic wave mother substrate having a plurality of interdigital transducers formed on one main surface thereof. A cut groove is formed in the substrate by cutting the surface acoustic wave mother substrate beginning from the one main surface side thereof. This step of forming a cut groove is repeated so as to produce a plurality of cut grooves so that the first reflection edge of the respective surface acoustic wave devices are sequentially formed. Next, similarly, cut grooves are sequentially formed on the surface acoustic wave mother substrate from the one main-face side thereof so as not to reach the other main surface thereof, whereby the second reflection edges of the respective surface acoustic wave devices are sequentially formed.

Abstract: A longitudinally coupled resonator type surface acoustic wave filter includes a piezoelectric substrate and first, second and third IDTs provided on the piezoelectric substrate and arranged in a surface wave propagating direction such that the second IDT is interposed between the first and the third IDTs. Each of the first, second and third IDTs has a plurality of electrode fingers. The first and second IDTs have narrow electrode-finger pitch sections that have an electrode-finger pitch narrower than the remaining electrode-finger pitches, at respective end portions of the first and second IDTs adjacent to each other. The second and third IDTs have narrow electrode-finger pitch sections that have an electrode-finger pitch narrower than the remaining electrode-finger pitches, at respective end portions of the second and third IDTs adjacent to each other.

Abstract: In a longitudinally coupled resonator type surface acoustic wave filter including narrow pitch electrode finger portions provided in the end portions of the neighboring IDT's, respectively each which contains a portion of the electrode fingers of the IDT having a narrower pitch than the remaining portions of the electrode fingers of the IDT, the inter-center distance between the centers of at least one pair of adjacent electrode fingers is deviated from 0.25&lgr;A+0.25&lgr;B, in which &lgr;A represents the wavelength determined by the pitch of one of the electrode fingers, and &lgr;B represents the wavelength determined by the pitch of the other electrode.

Abstract: A SAW filter includes input and output IDTs and a pattern inductor connected in parallel with the output IDT. The pattern inductor is constructed of a metallic thin film pattern of meander type with a self-inductance amount of 20 nH for example.

Abstract: The present invention relates to a surface acoustic wave filter which is characterized in that it includes a piezoelectric substrate, a plurality of surface acoustic wave propagation paths arranged in parallel on the piezoelectric substrate and a coupler for coupling the surface acoustic wave propagation paths, an input interdigital transducer and a first reflector are disposed on at least one of the surface acoustic wave propagation paths with intervention of the coupler, and an output interdigital transducer and a second reflector are disposed on at least one of the other surface acoustic wave propagation paths with intervention of the coupler. This construction can reduce the length of the surface acoustic wave filter in a surface acoustic wave propagation direction and can improve the shape factor of a frequency characteristic curve.

Abstract: Surface-acoustic-wave transducers include interdigital electrode fingers alternately connected to hot and ground bus bars. The gap between two adjacent electrodes has a relative tap weight proportional to the voltage difference between the two electrodes. A set of subtransducers connected in series, a string, has two ends that are connected to the major bus bars; several strings are connectable to a single pair of major bus bars. In string weighting a plurality of strings make up the number of different tap weights within the transducer. Here every subtransducer is preferably of minimal length, for example, nominally one wavelength. Since the full bus bar voltage is divided equally between the N subtransducers, the voltage at each tap is 1/N, and the length of the string is nominally N+1 wavelengths. Therefore, for a length of the transducer all taps have the same tap weight within each string.

Abstract: A unidirectional transducer for a SAW filter having a first group (D) including electrode finger (21) and electrode fingers (14) and (16) arranged at center distances of 3&lgr;/8 and 5&lgr;/8 in a direction opposite to the propagation direction of the surface acoustic wave from electrode finger (21); a second group (E) including electrode fingers (22), (15) and (20) arranged at center distances of 10&lgr;/8, 13&lgr;/8 and 15&lgr;/8 in the propagation direction from electrode finger (21); and a third group (F) including electrode fingers (17), (18) and (19) arranged at center distances of 3&lgr;/8, 5&lgr;/8 and 7&lgr;/8 in the propagation direction from electrode finger (21).

Abstract: A surface acoustic wave resonator including at least one interdigital transducer formed on a piezoelectric substrate, wherein the at least one interdigital transducer includes a predetermined number of interdigitated electrode fingers, at least two electrode fingers among the interdigitated electrode fingers are withdrawn, and the positions of the withdrawal electrode fingers are aperiodic.

Abstract: Surface-acoustic-wave transducers include interdigital electrode fingers alternately connected to hot and ground bus bars. The gap between two adjacent electrodes has a relative tap weight proportional to the voltage difference between the two electrodes. A set of subtransducers connected in series, a string, has two ends that are connected to the major bus bars; several strings are connectable to a single pair of major bus bars. In string weighting a plurality of strings make up the number of different tap weights within the transducer. Here every subtransducer is preferably of minimal length, for example, nominally one wavelength. Since the full bus bar voltage is divided equally between the N subtransducers, the voltage at each tap is 1/N, and the length of the string is nominally N+1 wavelengths. Therefore, for a length of the transducer all taps have the same tap weight within each string.

Abstract: A surface acoustic wave filter including a piezoelectric substrate, an exciting electrode formed on the piezoelectric substrate and exciting a surface acoustic wave, and a receiving electrode receiving the surface acoustic wave. Both the exciting and receiving electrodes are provided with interdigital electrode fingers having a period p. One of the exciting and receiving electrodes is constructed of a plurality of interdigital electrode sub-units having substantially the same electrode surface areas occupied by interdigital electrode fingers. The interdigital electrode sub-units are disposed in a direction perpendicular to a propagation direction of the excited surface acoustic wave and have a positional relation such that the interdigital electrode sub-units are offset from each other by (n±¼)p, wherein n is an integer, in a direction parallel to the propagation direction of the surface acoustic wave.

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.

Abstract: In a transversal surface acoustic wave filter, an interdigital transducer on the input side, an interdigital transducer on the output side, and a reflector are arranged in the surface acoustic wave propagation direction on a piezoelectric substrate. While a surface acoustic wave passes through the interdigital transducer on the output side and while the surface acoustic wave reflecting from the reflector passes through the interdigital transducer on the output side, the surface acoustic wave is converted to first and second electrical signals, respectively. The interval between the reflector and the interdigital transducer on the output side is set so that no phase difference is generated between the first and second electrical signals. The interdigital transducer on the output side adjacent to the reflector is weighted so that a part of the interdigital transducer on the output side having the highest excitation intensity is positioned on the reflector side thereof.

Abstract: A SAW device comprises input/output interdigital transducer (IDT) electrodes (11, 12) provided on piezoelectric substrates (10), a first reflector electrode (13) following the input IDT electrode (11), and a second reflector electrode (14) preceding the output IDT electrode (12). The device satisfies the following inequality (1) to provide preferable characteristics in a pass band: 2(&thgr;−5)≦tan−1(D/L)≦2(&thgr;+5) where &thgr;: the inclination (in degree, except zero) of the first or second reflector electrode of the input and output IDT electrodes with respect to a plane perpendicular to the direction in which surface acoustic waves travel. D: the pitch (in micron) of the input and output IDT electrodes in the direction in which surface acoustic waves travel. L: the pitch (in micron) of the first and second reflector electrodes.

Abstract: A surface acoustic wave resonator including at least one interdigital transducer formed on a piezoelectric substrate, wherein the at least one interdigital transducer includes a predetermined number of interdigitated electrode fingers, at least two electrode fingers among the interdigitated electrode fingers are withdrawn, and the positions of the withdrawal electrode fingers are aperiodic.

Abstract: A surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer on the piezoelectric substrate. The interdigital transducer includes first and second comb-shaped electrodes having one or more electrode fingers which are interdigitated with each other. When the first comb-shaped electrode is connected to a positive potential, the second comb-shaped electrode is connected to a negative potential, and the electrode finger connected to the positive potential and the electrode finger connected to the negative potential are reversed in at least one pair of the electrode fingers in an area where electrode fingers connected to the positive potential and electrode fingers connected to the negative potential are alternately arranged in the direction of surface-wave propagation.

Abstract: A dual-mode surface acoustic wave filter that can optionally be operated balanced or unbalanced, having tracks which are coupled to one another via coupling converters. The filter has interdigital converters for each track which are disposed within reflectors and act as input and output converters. The impedance of the input and/or output converters of the filter is determined by omission or overlap weighting and/or by splitting the input and output converters into a plurality of individual converters. At least some of the individual converters are connected in series, for each acoustic track.

Abstract: The transverse-mode resonator filter has reflectors and input and output converters arranged between the reflectors. The impedance of the input converter and/or the output converter is adjusted by reducing the original active finger overlap of the normal finger structure. The impedance can be increased by shortening the converter length of one converter, by reducing the active finger overlap of one converter by omission weighting, or by reducing the active finger overlap of one converter by overlap weighting.

Abstract: A multi-longitudinal-mode-coupled resonator type SAW filter having flat passband characteristic is provided. In the multi-longitudinal-mode-coupled resonator type SAW filter, an energy trapped type SAW resonator is formed on a frequency upward type piezoelectric substrate, and an IDT is divided into three IDTs, a first IDT arranged to a transmitter side, a second IDT arranged to a receiver side, and a third IDT arranged between the first IDT and the second IDT to control the amplitude of the vibration displacement in two modes for forming a filter. A frequency potential is optimized by changing an electrode period length of each IDT. Resonance amplitude strengths in the two modes are thus equalized and passband transmission characteristics are thus flattened. A filter having a relatively wide bandwidth of 1000 to 1500 ppm is fabricated by using a substrate having a small electromechanical coupling factor, such as a quartz crystal substrate.

Abstract: In accordance with the invention, magnetostrictive saw devices are provided with improved transducer structures for enhanced performance. In one improved device, the transducers are in the form of gratings with interconnected ends for reduced resistance and inductance. In another embodiment, the transducers are shaped to provide apodization. In yet a third embodiment, transducer performance is enhanced by patterning composite structures.

Abstract: A surface acoustic wave filter includes first and second channels, each channel including at least one input transducer and one input transducer. The transfer functions of the first channel and of the second channel are in phase in the passband of the filter and in antiphase in the rejection band of the filter. The filter enables the use of frequency responses for each channel, with wide bands enabling high reduction of the size of the filter while at the same time reducing the rejection band of the total filter. Such a filter may find particular application to mobile telephony.

Abstract: A SAW filter includes input and output IDTs and a pattern inductor connected in parallel with the output IDT. The pattern inductor is constructed of a metallic thin film pattern of meander type with a self-inductance amount of 20 nH for example.

Abstract: A surface acoustic wave matched filter for use in a spread spectrum communication system is disclosed. The surface acoustic wave matched filter includes a substrate having dispersity and is composed of a sapphire main body and a piezoelectric aluminum nitride. A tap distance L of an output side electrode is designed on the basis of a group velocity vg instead of a phase velocity vs in order to match the tap distance L with an input spread spectrum signal and to improve a correlation peak level of an output demodulated signal. When the tap distance L is set to satisfy a condition of vg/f1×0.97≦L≦vg/f1×1.02, a decrease in the correlation peak level of the matched filter can be improved from 7 dB to a value smaller than 3 dB, and S/N of the output demodulated signal can be increased. Thus, the disclosed device renders it no longer necessary to process the output demodulated signal by a complicated and power consuming circuit.

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.

Abstract: A reactance filter, particularly in a branching circuit (ladder type),with surface wave resonators wherein omission weighted normal finger transducers are employed between reflectors such that the arrangement and plurality of the active fingers of the interdigital transducer are particularly formed for changing the capacitance relationship (static to dynamic capacitance) such that a narrow filter bandwidth is achieved.

Abstract: An output side electrode of a surface acoustic wave matched filter with portions having different delay times between taps. The output side electrode may be provided by arranging parallelly a plurality of output side electrodes having different scales, different tap distances, or by forming output side electrodes in an inclined fashion or in a dog-leg shape viewed in a direction of an aperture length, or by arranging, between electrode fingers, thin films having different dimensions or thicknesses viewed in the direction of the aperture length, or by forming, between electrode fingers, recessed portions having different dimension or depth viewed in the direction of the aperture length.

Abstract: Twin dual mode filter with DMS filters have an input and output transducer (2; 12) per DMS track (A, B) within reflectors (3, 3) and further reflectors (7, 11) between the transducers that are respectively interconnected to one of the transducers. The reflectors (7, 11) of the input or, respectively, output side are respectively connected to one another via interconnects (8, 8). The DMS tracks (A, B) are frequency-shifted relative to one another such that the high-frequency resonance of the low-frequency track (B) falls onto the low-frequency resonance of the high-frequency track (A).

Abstract: A surface acoustic wave filter device suitable for CDMA communication system includes a piezoelectric substrate, and a unidirectional input side transducer and a bidirectional output side transducer are formed on the substrate. The filter device has satisfactory filtering characteristics in terms of insertion loss, frequency characteristic, T.T.E. attenuation level, group delay time, etc.

Abstract: A surface acoustic wave filter includes a piezoelectric substrate, input and output IDTs, and first and second direction changing electrodes, wherein at least one of the input and output IDTs includes a weighted interdigital transducer, the input and output IDTS being arranged in a direction perpendicular to a propagation direction of a surface acoustic wave (SAW) oscillated by the input IDT. The first direction changing electrode changes the propagation direction of the SAW, which has propagated in a left directed from the input IDT, into a direction towards the output IDT. The second direction changing electrode changes the propagation direction of the SAW, which has propagated in a right direction from the input IDT, into a direction towards the output IDTs and the first and second direction changing electrodes is set for obtaining at the output IDT the SAW having desired frequency characteristics.

Abstract: A surface acoustic wave filter. The filter includes two filter tracks which are parallel to each other. Each track has an input interdigital transducer, reflector and output interdigital transducer. This distance between the input transducer and output transducer is the same in both tracks. The distance between the output transducer and reflector is different in the two tracks. The electrical connection is in opposite phase in either the inputs or outputs, but not both. Electrode fingers are arranged in groups of two and have widths and spacings related to the wavelength.