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1. (WO1998013932) BRANCH FILTER AND SHARED DEVICE AND 2-FREQUENCY BAND MOBILE COMMUNICATION APPARATUS USING THE BRANCH FILTER

Pub. No.:    WO/1998/013932    International Application No.:    PCT/JP1997/003381
Publication Date: Apr 2, 1998 International Filing Date: Sep 24, 1997
IPC: H03H 3/00
H03H 7/46
H04B 1/40
H04B 1/48
H04B 1/52
Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.

HIRAKA, Masahiro

KATSUMURA, Hidenori

SAITO, Ryuichi

KUSHITANI, Hiroshi

YUDA, Naoki

HURUKAWA, Shigeo

KIMURA, Suzushi

Inventors: HIRAKA, Masahiro

KATSUMURA, Hidenori

SAITO, Ryuichi

KUSHITANI, Hiroshi

YUDA, Naoki

HURUKAWA, Shigeo

KIMURA, Suzushi

Title: BRANCH FILTER AND SHARED DEVICE AND 2-FREQUENCY BAND MOBILE COMMUNICATION APPARATUS USING THE BRANCH FILTER
Abstract:
A branch filter which is used for mobile communication such as a portable telephone and the purpose of the invention is that a band separates two bands with a simple construction in such a way that mutual influence between both the bands is provided. An inductor (105) which is a 1st matching circuit is connected between a single-pole π-type 3-stage low-pass filter (115) and a common terminal (113), and a capacitor (106A) which is a 2nd matching circuit is connected between a single-pole band-pass filter (116) and the common terminal (113). Thus the mutual influence between both the bands is eliminated, and harmonic components are sufficiently attenuated.