The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
May. 23, 2000

Filed:

Jul. 10, 1998
Applicant:
Inventors:

Kazuya Yamamoto, Tokyo, JP;

Takao Moriwaki, Tokyo, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01P / ; H04B / ;
U.S. Cl.
CPC ...
333103 ; 455 83 ;
Abstract

A duplexer circuit apparatus includes (a) a transmission arm circuit including a first switching circuit which is connected between a transmitter and an antenna, is turned on during transmission, and is turned off during reception, and (b) a reception arm circuit including a second switching circuit which is connected between a receiver and the antenna, is turned off during transmission, and is turned on during reception. In the duplexer circuit apparatus, either the transmitter or the receiver is selectively connected to the antenna, and the transmission arm circuit further includes a cascode amplifier, and an impedance matching inductor connected between the cascode amplifier and the antenna. In this case, the cascode amplifier may be replaced by a source-grounded amplifier constituted by only the FET.


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