Sanyo Electric Co., Ltd.

Other

Yasutaka Shimizu

Yasuhiro Hirao

Kenichi Shibata

Yasumi Kobayashi

Kuniyuki Matsui

Kousuke Takeuchi

Yusuke Takahashi

Toshiharu Tanaka

Kosuke Takeuchi

Tateo Kondo

Hiroshi Kayaki

Isao Kiyose

Masami Ikeda

Kazuhiro Kuroki

A coaxial resonator according to the present invention has an outer conductor on an outer peripheral surface of a dielectric block having at least four side surfaces and having a through hole provided in its approximately central part and an inner conductor on an inner peripheral surface of the through hole, and one of two end faces perpendicular to the through hole is opened and the other end face is short-circuited. A pair of an input electrode and an output electrode which are not brought into electrical contact with the outer conductor and are independent of each other is provided in a position in proximity to the opened end face on the outer peripheral surface of the dielectric block, and respective portions of both the electrodes are extended to the side surfaces, which are respectively adjacent to the electrodes, of the dielectric block. Consequently, the input electrode and the output electrode are capacitively coupled to each other, and the input electrode and the output electrode are respectively capacitively coupled to the inner conductor. Coupling capacitance can be adjusted by the areas of the electrodes.

Coaxial resonator and dielectric filter using the same

The invention provides a surface acoustic wave device which has a thin film formed on a surface of a substrate adapted to excite longitudinal wave-type surface acoustic waves, longitudinal wave-type quasi surface acoustic waves or longitudinal wave-type surface skimming bulk waves to thereby give an increased electromechanical coupling coefficient and at the same time minimize the temperature coefficient of delay time. For example, in a surface acoustic wave device having an aluminum thin film formed on a surface of a lithium tantalate substrate, the direction of propagation of longitudinal wave-type quasi surface acoustic waves is (40 deg to 90 deg, 40 deg to 90 deg, 0 deg to 60 deg) as expressed in Eulerian angles and within a range equivalent thereto, and the product of wave number of longitudinal wave-type quasi surface acoustic waves and the thickness of the thin film is at least 1.0, preferably in the range of 1.3 to 2.0. The device provided exhibits higher performance than in the paior art.

Surface acoustic wave device

A surface acoustic wave filter having one or a plurality of filter functional units each comprising a series arm resonator and a parallel arm resonator. Each of the series arm resonator and the parallel arm resonator is constituted by an interdigital transducer and grating reflectors formed on a piezoelectric substrate composed of 64.degree.-rotated Y-cut X-propagating LiNbO.sub.3. The series arm resonator is constructed by electrically connecting a one-port resonator in series with a signal line, and the parallel arm resonator is constructed by electrically connecting a one-port resonator in parallel with the signal line. In the interdigital transducer in the series arm resonator and/or the parallel arm resonator, one or more sets of electrode fingers continuously adjacent to each other are formed.

Integrated interdigital electrode saw filter with specified distances

A surface acoustic wave filter according to the present invention is constructed by connecting in series one or two or more filter functional units each comprising a first surface acoustic wave resonator having input and output terminals connected in series with a signal line and a second surface acoustic wave resonator having input and output terminals one of which is connected to the signal line and the other of which is grounded. The first surface acoustic wave resonator is constituted by one interdigital transducer and a pair of electrically open strip type grating reflectors with the interdigital transducer interposed therebetween, and the second surface acoustic wave resonator is constituted by one interdigital transducer and a pair of electrically short strip type grating reflectors with the interdigital transducer interposed therebetween.

Surface acoustic wave filter including series and parallel interdigital

A surface acoustic wave filter according to the present invention has one or a plurality of filter functional units each comprising a series arm resonator and a parallel arm resonator. Each of the series arm resonator and the parallel arm resonator is constituted by a interdigital transducer and grating reflectors formed on a piezoelectric substrate composed of 64.degree.-rotated Y-cut X-propagating LiNbO.sub.3. The series arm resonator is constructed by electrically connecting a one-port resonator in series with a signal line, and the parallel arm resonator is constructed by electrically connecting a one-port resonator in parallel with the signal line. In the interdigital transducer in the series arm resonator and/or the parallel arm resonator, one or more sets of electrode fingers continuously adjacent to each other are formed.

Surface acoustic wave filter utilizing a transducer having interdigital

A high-frequency filter having series and parallel electrode patterns formed on a mount substrate, surface acoustic wave resonators connected to a signal input/output line of the electrode patterns in series, and coaxial dielectric resonators having respective one input/output terminals connected to the signal input/output line and the other input/output terminals connected to a ground element. In such a composite high-frequency filter, the surface acoustic wave resonators form the resonators in the serial arms while the coaxial dielectric resonators form resonators in the parallel arms. The high-frequency filter can meet all the requirements of enhanced miniaturization, selectivity and power handling.

High frequency filter including both dielectric and surface acoustic

In a resonator-type surface acoustic wave filter comprising a lithium tantalate substrate, lithium niobate substrate or lithium tetraborate substrate having a cut plane of high velocity, the direction of propagation of surface acoustic waves is set within the range of (40 deg to 90 deg, 40 deg to 90 deg, 0 deg to 60 deg) as expressed in Eulerian angles, and the capacitance Cos of the series resonators and the capacitance Cop of the parallel resonators are set within a predetermined range formulated with the center frequency taken as a parameter. Optimum ranges of the required design parameters are thus clarified to assure the resonator-type surface acoustic wave filter of higher performance.

Surface acoustic wave filter with optimized parallel and series

In a resonator-type surface acoustic wave filter comprising a lithium tantalate substrate, lithium niobate substrate or lithium tetraborate substrate having a cut plane of high velocity, the direction of propagation of surface acoustic waves is set within the range of (40 deg to 90 deg, 40 deg to 90 deg, 0 deg to 60 deg) as expressed in Eulerian angles, and the frequency difference .increment.f between the resonance frequency frs of series resonators and the resonance frequency frp of parallel resonators is set within a predetermined range formulated with the center frequency, the capacitance Cos of the series resonators and the capacitance Cop of the parallel resonators taken as parameters. Optimum ranges of the required design parameters are thus clarified to assure the resonator-type surface acoustic wave filter of higher performance.

Surface acoustic wave filter with range of a frequency difference

A surface acoustic wave convolver of the present invention includes, on a surface of a piezoelectric substrate, a pair of comb-like surface acoustic wave excitation electrodes 2 and 3, and a center electrode 4. The excitation electrodes 2 and 3 are disposed opposed to each other at a specified interval while the center electrode 4 having a shorter width than a length of the excitation electrodes 2 and 3 is positioned between the electrodes 2 and 3. The center electrode 4 propagates the surface acoustic waves respectively produced by the excitation electrodes 2 and 3 in reverse directions to each other to obtain a convolution output signal. A pair of reflectors 10 are positioned on opposite sides of a region defined between the excitation electrode 2 and one end of the center electrode 4 with a width equivalent to that of the center electrode 4. Also, a pair of reflectors 11 are positioned on opposite sides of a region defined between the excitation electrode 3 and the other end of the center electrode 4 with a width equivalent to that of the center electrode 4.

Surface acoustic waver convolver

Surface accoustic wave filter

Surface acoustic wave filter including alternate open and shorted

An object of the present invention is to improve the characteristics of the conventional antenna duplexer and to provide an antenna duplexer contributing to higher performance and smaller size of a mobile communication apparatus. The antenna duplexer has a filter for wave receiving and a filter for wave transmission, and respective one ends of both the filters are connected to an antenna shared terminal through a matching circuit constituted by transmission lines. The characteristic impedance of at least one of a transmission line for connecting the antenna shared terminal and the filter for wave receiving to each other and a transmission line for connecting the antenna shared terminal and the filter for wave transmission to each other is set to a value other than the standard characteristic impedance of a receiver circuit and a transmitter circuit connected to the antenna duplexer. The total impedance of the filters for wave transmission and wave receiving and the respective transmission lines is set to the standard characteristic impedance.

Growing community of inventors

Osaka-fu, Japan

Yasuhiro Hirao