Oki Electric Industry Co., Ltd.

Oki Semiconductor Co., Ltd.

Electric Industry Co., Ltd.

Tomokazu Komazaki

Yoshiaki Fujita

Katsuhiko Gunji

Hajime Shimamura

Akira Mashimo

Wataru Ohashi

Norio Onishi

Kazushige Noguchi

Hisanori Ehara

Hiroyuki Horii

Satoshi Terada

Toshikazu Yasuoka

Masao Iwata

Yoshio Okada

Kenichi Anasako

Ichiro Iwase

Izumi Kawakami

Kouichi Ichikawa

Kohichiro Shimizu

Akira Nakano

Osamu Yamato

Yoshikazu Kihara

Akio Hirakawa

Masaaki Umezawa

Yoshimitu Sakurai

Yoshimitsu Sakurai

Kazushige Nogichi

Kunihiro Tanoie

Koichiro Shimizu

Tsuyoshi Miyazawa

Norio Onisi

Katuhiko Gunzi

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.

Branching filter package

A surface acoustic wave filter includes an antenna terminal, a transmitting filter and a variable branching line both of which are coupled to the antenna terminal and a receiving filter coupled to the variable branching line. The transmitting filter has a first end series-arm SAW resonator, a second end series-arm SAW resonator, a middle series-arm SAW resonator coupled between the first and second end series-arm SAW resonators and parallel-arm SAW resonators. Each of the first and second end series-arm SAW resonator has a first resonance frequency. The middle series-arm SAW resonator has a second resonance frequency that is higher than the first resonance frequency.

Transmitting filter including SAW resonators

A SAW filter circuit has: a first circuit having first to fourth connecting points, a first SAW resonator electrically connected to the first and second connecting points, second SAW resonator electrically connected to the first and third connecting points, and third SAW resonator electrically connected to the second and fourth connecting points; and a second circuit made of a fifth connecting point electrically connected to the third connecting point, a sixth connecting point electrically connected to the fourth connecting point, seventh and eighth connecting points being electrically short-circuited, a first passive element electrically connected to the fifth and sixth connecting points, a second passive element electrically connected to the fifth and seventh connecting points, and a third passive element electrically connected to the sixth and eighth connecting points. Each passive elements is an inductor or capacitor, and at least one of the first to third passive elements is a capacitor.

Saw filter circuit

A filter chip lying on an upper surface of a top layer package substrate is connected to an upper surface ground electrode (). The upper ground electrode () and a lower surface ground electrode () are connected to each other via through electrodes (), ground wiring patterns (), first connecting lines (to), and second connecting lines (). The first connecting lines (to) are connected to the ground wiring patterns (), whereas the second connecting lines () are not connected to the ground wiring patterns (), respectively. Owing to the provision of the connecting lines connected to the ground wiring patterns () and the connecting lines unconnected to the ground wiring patterns (), the impedance between a multilayer package substrate and ground can be adjusted.

Duplexer

A high-performance SAW filter is to be provided which has lower insertion loss in a pass band and high attenuation in an attenuation band on the low frequency side of the pass band. In a SAW filter with attenuation poles configured of a two-port circuit for filtering for forming a ladder type SAW filter using a SAW resonator and a two-port circuit for impedance formed of an impedance serially connected, the impedance of the two-port circuit for impedance is configured so as to form an attenuation band of a predetermined width having a sufficient attenuation characteristic on the low frequency side of a pass band.

Surface acoustic wave filter with attenuation poles

Acoustic wave branching filter having transmitting filter with optimal power handling

A surface acoustic wave duplexer having an antenna terminal, a transmitting terminal and a receiving terminal. The surface acoustic wave duplexer includes a transmitting SAW filter coupled between the antenna terminal and the transmitting terminal, a receiving SAW filter coupled between the antenna terminal and the receiving terminal, a common piezoelectric substrate on which both of the transmitting SAW filter and the receiving SAW filter are formed, a package covering the common piezoelectric substrate. The antenna terminal, the transmitting terminal and the receiving terminal are formed on the package, and a frequency adjusting circuit is coupled between the antenna terminal and the transmitting SAW filter or the receiving SAW filter. The frequency adjusting circuit has a capacitance element.

Saw branching filter with a branching filter circuit formed on the package

A surface acoustic wave filter includes an antenna terminal, an antenna, a transmitting filter, a branching line and a receiving filter. The antenna is coupled to the antenna terminal. The transmitting filter is coupled to the antenna terminal. The transmitting filter receives an electrical power. The branching line is coupled to the antenna terminal. The branching line has a first length that is longer than &#x3bb;/4 length so that the electrical power received by the transmitting filter when the antenna terminal is opened is smaller than when the antenna terminal is terminated, wherein &#x3bb; is a wave length of a center frequency of transmitted and received bands of the surface acoustic wave filter. The receiving filter is coupled to the branching line.

Surface acoustic wave filter

A surface acoustic wave duplexer includes a piezoelectric substrate; a transmitting filter formed on the piezoelectric substrate; a receiving filter formed on the piezoelectric substrate; a transmitting (Tx) branching line formed on the piezoelectric substrate; and a receiving (Rx) branching line formed on the piezoelectric substrate.

Surface acoustic wave duplexer and portable communication device using the same

A polar SAW (Surface Acoustic Wave) filter includes a band-pass ladder type SAW filter having a SAW resonator. A two-terminal pair circuit is serially connected to the band-pass ladder type SAW filter and includes a plurality of inductors. The polar SAW filter has attenuation poles in each of the higher-frequency and lower-frequency attenuation ranges of a pass band.

Saw filter with an attenuation pole including a band-pass ladder type of saw filter having a saw resonator

Growing community of inventors

Tokyo, Japan

Tomokazu Komazaki