Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2002-10-01
2004-10-26
Summons, Barbara (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S193000, C333S202000, C333S206000
Reexamination Certificate
active
06809611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composite filter used for a communication apparatus such as a portable phone terminal, an antenna duplexer, and a communication apparatus.
2. Related Art of the Invention
A filter is usually used for a communication apparatus such as a portable phone terminal. There is a multi-input/single-output filter, which receives a plurality of signals and outputs one signal, as one of such filters.
FIG. 7
shows the structure of a portable phone terminal
60
. A conventional multi-input/single-output filter like this is used for the portable phone terminal
60
. The portable phone terminal
60
is a dual band terminal, which can perform radiocommunication, by using either of two frequency bands of a 1.5-GHz frequency band and an 800-MHz band.
FIG. 2
shows the frequency composition of the 800-MHz band that the portable phone terminal
60
uses.
A D band
23
and a D band
28
are frequency bands used in a communication system where the portable phone terminal
60
performs transmission and reception simultaneously. The D band
23
is a band used for reception in the portable phone terminal
60
, and the D band
28
is a band used for transmission in the portable phone terminal
60
.
An A-band
25
and an A-band
27
are frequency bands used in a communication system different from the above-described system. The A-band
25
is a band used for reception in a portable phone terminal, and the A-band
27
is a band used for transmission in the portable phone terminal. The communication system that uses the A-band
25
and A-band
27
is a communication system not performing the simultaneous transmission and reception. A C band
24
and a C band
26
are frequency bands used in a communication system the same as the above-described communication system. The C band
24
is a band used for reception in the portable phone terminal
60
, and the C band
26
is a band used for transmission in the portable phone terminal
60
. The communication system that uses the C band
24
and C band
26
is a communication system not performing the simultaneous transmission and reception the same as the above. The portable phone terminal
60
can use each communication system corresponding to the D band, A-band, or C band by switching the bands according to a region such as a country where the portable phone terminal
60
is used. Specifically, a communication system that uses the D band is, for example, a PDC full duplex system. A communication system that uses the A-band is, for example, a usual timesharing PDC system, and a communication system that uses the C band is also, for example, a usual timesharing PDC system. In addition, it is needless to say that any communication system besides this is sufficient so long as the communication system that uses the D band is a communication system performing the transmission and reception simultaneously and the communication system that uses the A-band and C band is a communication system not performing the transmission and reception simultaneously.
The portable phone terminal
60
comprises a transmitting circuit section
1
, a receiving circuit section
2
, a base band section
3
, a switch
4
, an antenna
5
, an antenna
6
, a 1.5-GHz band SAW filter
17
, and, a composite filter
33
.
The base band section
3
is a circuit that modulates a base band signal, outputs the modulated signal as an intermediate frequency signal to the transmitting circuit section
1
, and demodulates the intermediate frequency signal inputted from the receiving circuit section
2
to output a sound signal. In addition, the base band section
3
contains a frequency converter that converts the base band signal into the intermediate frequency signal and converts the intermediate frequency signal into the base band signal.
The transmitting circuit section
1
is a circuit that outputs either a 1.5-MHz band transmitted-signal or an 800-MHz band transmitted-signal. In addition, the switching of which of the 1.5-GHz band transmitted signal and the 800-MHz band transmitted-signal are outputted is performed by a controlling circuit not shown.
The transmitting circuit section
1
comprises an upconverter
7
a
, a variable gain amplifier
81
a
, a filter
8
a
, a power amplifier
9
a
, a coupling capacitor
10
, an isolator
11
, a filter
12
, an upconverter
7
b
, a variable gain amplifier
81
b
, a filter
8
b
, a power amplifier
9
b
, and a directional coupler
13
.
The upconverter
7
a
is means of converting the intermediate frequency signal outputted from the base band section
3
into the 800-MHz band signal. The variable gain amplifier
81
a
is an amplifier whose gain is controlled by a controlling circuit not shown, and which amplifies the 800-MHz band signal, which is converted, in such a gain that the 800-MHz band signal may become a determined transmission power output. The filter
8
a
is a band-pass filter decreasing an unnecessary frequency component of the 800-MHz band signal outputted from the upconverter
7
a
. The power amplifier
9
a
is means of amplifying the signal outputted from filter
8
a
to a transmission output. The coupling capacitor
10
supplies a power monitor signal to adjust the output power of the power amplifier
9
a
. The isolator
11
passing the transmitted signal, outputted by the power amplifier
9
a
, to the filter
12
, and interrupting the transmitted signal reflected from the filter
12
. The filter
12
decreasing an unnecessary frequency component of the signal outputted from the isolator
11
.
The upconverter
7
b
converts the intermediate frequency signal, outputted from the base band section
3
, into a 1.5-GHz band signal. The variable gain amplifier
81
b
is an amplifier whose gain is controlled by a controlling circuit not shown, and which amplifies the 1.5-GHz band signal, which is converted, in such a gain that the 1.5-GHz band signal may become a determined transmission power output. The filter
8
b
decreases an unnecessary frequency component of the 1.5-GHz band signal outputted from the upconverter
7
b
. The power amplifier
9
b
amplifies the signal outputted from the filter
8
b
to a transmission output. The directional coupler
13
passes the signal, outputted from the power amplifier
9
b
, to the switch
4
and not passing a reflected wave from the switch
4
to the power amplifier
9
b
, and supplies a power monitor signal to a controlling circuit that adjusts the output power of the power amplifier
9
b
and is not shown.
The receiving circuit section
2
converts the signal, inputted from the composite filter
33
, into the intermediate frequency signal to output the signal to the base band section
3
.
The receiving circuit section
2
comprises a low-noise amplifier
19
a
, a filter
20
a
, a mixer
21
a
, a low-noise amplifier
19
b
, a filter
20
b
, a mixer
21
b
, and a filter
22
.
The low-noise amplifier
19
a
amplifies the 800-MHz band signal received. The filter
20
a
decreases an unnecessary frequency component of the signal amplified by the low-noise amplifier
19
a
. The mixer
21
a
is a signal, which passed the filter
20
a
, into the intermediate frequency signal.
The low-noise amplifier
19
b
amplifies the 1.5-GHz band signal received. The filter
20
b
decreases an unnecessary frequency component of the signal amplified by the low-noise amplifier
19
b
. The mixer
21
b
converts a signal, which passed the filter
20
b
, into the intermediate frequency signal.
Moreover, the filter
22
decreases an unnecessary frequency component included in the signal converted into the intermediate frequency.
The 1.5-GHz-band-receiving SAW filter
17
is a surface acoustic wave filter that passes the 1.5-GHz band signal received, and attenuates a signal except the 1.5-GHz band that is used for reception.
The composite filter
33
is a multi-input/single-output filter having a plurality of inputs and one output.
The composite filter
33
comprises a dielectric filter
30
, an A-band-receiving SAW filter
31
, and a switch
32
Ishizaki Toshio
Nakamura Hiroyuki
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
Summons Barbara
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