Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2000-09-05
2002-10-29
Bettendorf, Justin P. (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S134000
Reexamination Certificate
active
06472952
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a high frequency wireless circuit apparatus mainly used in mobile communication appliances such as a portable telephone and an information communication terminal.
2. Background Art
Generally, the high frequency wireless circuit apparatus of this type has been composed as shown in FIG.
6
. In the drawing, the reference numeral
11
denotes an antenna;
12
denotes a switch;
13
denotes an antenna duplexer;
14
denotes an isolator;
15
denotes a power amplifier;
16
denotes a low noise amplifier;
17
denotes a transmitting input terminal; and
18
denotes a receiving output terminal. The antenna duplexer
13
and the low noise amplifier
16
have been connected directly without any interposing means. Reference numerals
21
,
22
are respectively a transmitting terminal and a receiving terminal of the antenna duplexer
13
.
The transmission signal input from the transmitting input terminal
17
is amplified in the power amplifier
15
, and is fed into the transmitting terminal
21
of the antenna duplexer
13
through the isolator
14
. The isolator
14
is provided so that the transmission characteristic of the power amplifier
15
may not fluctuate even if the load of the antenna
11
changes. The transmission signal output from the antenna duplexer
13
is radiated into the air from the antenna
11
through the switch
12
.
On the other hand, the reception signal input from the antenna
11
is fed into the antenna duplexer
13
through the switch
12
, and is output into the receiving terminal
22
of the antenna duplexer
13
. This reception signal is input to the low noise amplifier
16
through a phase shifter
10
, and amplified, and sent out to the receiving output terminal
18
.
The transmission signal fed into the antenna duplexer
13
is also sent to the receiving terminal
22
of the antenna duplexer
13
. The switch
12
is not always necessary, or two or more switches may be connected to the contrary.
In such conventional structure, however, when the antenna duplexer
13
and the low noise amplifier
16
are directly connected, the transmission power amplified in the power amplifier
15
passes through the receiving terminal
22
of the antenna duplexer
13
and is mixed into the low noise amplifier
16
. The transmission power amplified possibly causes cross modulation with an incoming interference signal from the antenna
11
. As a result the reception sensitivity deteriorates.
In particular, this phenomenon occurs frequently in the CDMA system wireless communication, and it has been difficult to satisfy the interference wave input level of −30 dBm in the single wave interference characteristic determined in the standard.
That is, in the case of CDMA system wireless communication, the transmission signal output to the reception signal terminal
22
of the antenna duplexer
13
is modulated by CDMA, and has a modulation band width. On the other hand, the reception signal input through the antenna
11
is a CDMA modulated wave same as the transmission signal, but the interference signal input through the antenna
11
is a non-modulated signal. When the nonmodulated interference wave and the CDMA modulated transmission signal are fed into the low noise amplifier
16
, the two-wave input distortion occurs. Then the intermodulation distortion and cross modulation distortion occurs. The CDMA modulated wave has a band. Then the wave caused by the cross modulation of interference waves and the transmission wave covers the reception signal band, thereby disabling the reception.
Disclosure of the Invention
It is hence an object of the invention to enhance the reception sensitivity and immunity to interference signals in a high frequency wireless circuit apparatus used in mobile communication appliances such as a portable telephone and an information communication terminal.
To achieve the object, the high frequency wireless circuit apparatus of the invention is composed by connecting a phase shifter between an antenna duplexer and a low noise amplifier, so that the impedance of the receiving terminal of the antenna duplexer at a transmission frequency and the input impedance of the low noise amplifier may not be matched in complex conjugates of each other. It prevents the transmission output passing through the receiving terminal of the antenna duplexer and the interference signal entered through the antenna from causing the cross modulation in the low noise amplifier. Thus the reception sensitivity and immunity to interference signal of the high frequency wireless circuit apparatus improve at the same time.
REFERENCES:
patent: 4692726 (1987-09-01), Green et al.
patent: 5554960 (1996-09-01), Ohnuki et al.
patent: 5768692 (1998-06-01), Kwak
patent: 5784687 (1998-07-01), Itoh et al.
patent: 5903820 (1999-05-01), Hagstrom
patent: 6032031 (2000-02-01), Takaki
patent: 1-133477 (1989-05-01), None
patent: 1-503428 (1989-11-01), None
patent: 3-101523 (1991-04-01), None
patent: 6-7332 (1994-01-01), None
patent: 1998-0009080 (1989-07-01), None
patent: 1998-033270 (1998-07-01), None
Japanese Search Report corresponding to application No. PCT/JP99/06191 dated Feb. 8, 2000.
Sakai Yukio
Tsuneoka Michiaki
Yahata Kazuhiro
Bettendorf Justin P.
Cathey Damian E.
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
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