Abstract: A surface acoustic wave filter comprised of a plurality of surface acoustic wave resonators having different resonance frequencies, the filter comprising a substrate made of lithium niobate, comb electrodes (1201 and 1202) formed on the substrate, and a thin dielectric film covering the comb electrodes (1201 and 1202), wherein the surface acoustic wave resonator having a lower resonance frequency is formed to have a metallization ratio larger than a metallization ratio of the surface acoustic wave resonator having a higher resonance frequency, thereby providing the surface acoustic wave filter and an antenna duplexer featuring superior characteristics with insignificant ripples while suppressing spurious responses of the surface acoustic wave resonators.

Abstract: The present invention provides a surface acoustic wave resonator capable of improving a leak of a surface acoustic wave in the transverse direction and reducing the spurious and having superior characteristics. In a surface acoustic wave filter according to the present invention, an interdigital transducer electrode and reflector electrodes are formed on a piezoelectric substrate, and a SiO2 thin film is formed on at least a portion of the interdigital transducer electrode. The interdigital transducer electrode includes a bus-bar electrode region, a dummy electrode region and a finger overlap region, such that the SiO2 thin film is removed from upper sections of the bus-bar electrode regions of the interdigital transducer electrode.

Abstract: A surface acoustic wave filter includes a piezoelectric substrate including lithium niobate, a series resonator including a first interdigital transducer electrode provided on the piezoelectric substrate, and a parallel resonator including a second interdigital transducer electrode provided on the piezoelectric substrate and being electrically connected to the series resonator. An apodized weighting factor of the first interdigital transducer electrode is smaller than an apodized weighting factor of the second interdigital transducer electrode. This surface acoustic wave filter has a small loss.

Abstract: The present invention provides a surface acoustic wave resonator capable of improving the leak of a surface acoustic wave in the transverse direction and reducing the spurious and having superior characteristics. In a surface acoustic wave filter according to the present invention, an interdigital transducer electrode and reflector electrodes are formed on a piezoelectric substrate, and a SiO2 thin film is further formed thereon. The interdigital transducer electrode includes a bus-bar electrode region, a dummy electrode region and a finger overlap region, and the SiO2 thin film is removed from upper sections of the bus-bar electrode regions in the interdigital transducer electrode.

Abstract: A surface acoustic wave filter comprised of a plurality of surface acoustic wave resonators having different resonance frequencies, the filter comprising a substrate made of a lithium niobate, comb electrodes (1201 and 1202) formed on the substrate, and a thin dielectric film covering the comb electrodes (1201 and 1202), wherein the surface acoustic wave resonator having a lower resonance frequency is formed to have a metallization ratio larger than a metallization ratio of the surface acoustic wave resonator having a higher resonance frequency, thereby providing the surface acoustic wave filter and an antenna duplexer featuring superior characteristics with insignificant ripples while suppressing spurious responses of the surface acoustic wave resonators.

Abstract: A surface acoustic wave resonator has a piezoelectric substrate (11), an IDT (13) formed of a plurality of electrode fingers (12) disposed on piezoelectric substrate (11), and reflectors (14) disposed near the opposite ends of IDT (13). The IDT (13) has a gradation region where the electrode finger pitch of the plurality of electrode fingers (12) at the opposite ends is different from the electrode finger pitch near the center of the IDT (13). In this gradation region, the electrode finger pitches are sequentially varied in the range from the electrode finger at the farthest end that is one end of the gradation region to the electrode finger lying at the other end of the gradation region. The electrode finger pitch of the electrode fingers at the farthest end that is one end of the gradation region is set to be 1 through 5% smaller than the electrode finger pitch near the center of the IDT (13).

Abstract: A surface acoustic wave resonator has piezoelectric substrate (11), IDT (13) formed of a plurality of electrode fingers (12) disposed on piezoelectric substrate (11), and reflectors (14) disposed near the opposite ends of IDT (13). IDT (13) has a gradation region where the electrode finger pitch of the plurality of electrode fingers (12) at the opposite ends is different from the electrode finger pitch near the center of IDT (13). In this gradation region, the electrode finger pitches are sequentially varied in the range from the electrode finger at the farthest end that is one end of the gradation region to the electrode finger lying at the other end of the gradation region. The electrode finger pitch of the electrode fingers at the farthest end that is one end of the gradation region is set to be 1 through 5% smaller than the electrode finger pitch near the center of IDT (13).

Abstract: A SAW filter is configured by forming a first IDT and a second IDT on a piezoelectric substrate, and the first IDT is arranged between one terminal of input/output terminals and another terminal of the input/output terminals, i.e., serially in a signal path, and the second IDT is arranged in parallel to a signal path from a portion between one terminal of the input/output terminals and the first IDT. The first IDT and the second IDT are arranged in proximity to each other and on the same propagation path of surface acoustic waves which are excited by each of the resonators.

Abstract: A surface acoustic wave filter includes a piezoelectric substrate including lithium niobate, a series resonator including a first interdigital transducer electrode provided on the piezoelectric substrate, and a parallel resonator including a second interdigital transducer electrode provided on the piezoelectric substrate and being electrically connected to the series resonator. An apodized weighting factor of the first interdigital transducer electrode is smaller than an apodized weighting factor of the second interdigital transducer electrode. This surface acoustic wave filter has a small loss.

Abstract: It is configured by forming first IDT (202) and second IDT (203) on piezoelectric substrate (201), and first IDT (202) is arranged between one terminal (204) of input/output terminals and other terminal (205) of the input/output terminals, i.e., serially to a signal path, and second IDT (203) is arranged in parallel to a signal path from a portion between one terminal (204) of the input/output terminals and first IDT (202). First IDT (202) and second IDT (203) are arranged in proximity to each other on the same propagation path of surface acoustic waves which are excited by respective resonators.

Abstract: An interdigital transducer has one-wavelength basic units of a single phase unidirectional transducer a plurality of each having three electrode fingers within one wavelength; and a plurality of one-wavelength basic units of a bidirectional electrode each having four electrode fingers within the one wavelength, wherein the one-wavelength basic units are properly arranged according to a desired filter characteristic, and one of the three electrode fingers of each one-wavelength basic unit of the single phase unidirectional transducer is wider than the two other electrode fingers, and of the four electrode fingers of each one-wavelength basic unit of the bidirectional electrode, one pair of two fingers is interdigitated to the other pair of two fingers, and an adjustment section is provided between the one-wavelength basic units of the single phase unidirectional transducer and the one-wavelength basic units of the bidirectional electrode.

Abstract: An interdigital transducer has

Abstract: An interdigital transducer has one-wavelength basic units of a single phase unidirectional transducer a plurality of each having three electrode fingers within one wavelength; and a plurality of one-wavelength basic units of a bidirectional electrode each having four electrode fingers within the one wavelength, wherein the one-wavelength basic units are properly arranged according to a desired filter characteristic, and one of the three electrode fingers of each one-wavelength basic unit of the single phase unidirectional transducer is wider than the two other electrode fingers, and of the four electrode fingers of each one-wavelength basic unit of the bidirectional electrode, one pair of two fingers is interdigitated to the other pair of two fingers, and an adjustment section is provided between the one-wavelength basic units of the single phase unidirectional transducer and the one-wavelength basic units of the bidirectional electrode.

Abstract: A surface acoustic wave filter has a piezoelectric substrate and at least two interdigital transducer electrodes on the piezoelectric substrate, wherein at least one of the interdigital transducer electrodes includes a unidirectional electrode and bidirectional electrode, and the length &lgr;d of a basic cell of the unidirectional electrode is longer than the length &lgr;s of a basic cell of the bidirectional electrode.

Abstract: An interdigital transducer has

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 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 SAW filter comprising a piezoelectric substrate and at least two filter tracks formed on the substrate, each having at least two IDT electrodes for input and output. The two filter tracks have substantially the same phase within a pass band, while it is substantially inverse-phased outside the pass band. For realizing the above-described conditions, input IDT electrode of one filter track is connected in parallel with input IDT electrode of the other filter track, while output IDT electrode of one filter track is connected in parallel with output IDT electrode of the other filter track. Furthermore, frequency values of said two filter tracks substantially coincide at a point 3 dB lower from the peak transfer function value. Thus the above-configured SAW filter of the present invention is smaller in the overall size and offers a broad pass band and a steep attenuation characteristic.

Abstract: A surface acoustic wave filter has a piezoelectric substrate and at least two interdigital transducer electrodes on the piezoelectric substrate,

Abstract: A surface acoustic wave (SAW) filter is disclosed which comprises a piezoelectric substrate and at least two Interdigital Transducers (IDTs) having four fingered electrodes in a region corresponding to one-wavelength of SAW excited on the piezoelectric substrate. At least one IDT is formed of at least one pair of fingered electrodes having different electrode widths. By provision of the pair of fingered electrodes being different in electrode width, the IDT can be given unidirectionality. Thus, a SAW filter producing a low insertion loss and having good amplitude and phase characteristics in the pass-band can be realized. Further, by using such SAW filter, a high-performance and low-cost communication apparatus, such as a CDMA-system mobile telephone, can be realized.