JP2003209484A - Transmitter/receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of receiving characteristics of a signal by making available a SAW filter in the unbalanced output system of high characteristics. <P>SOLUTION: The device has a diplexer 14 connected to an antenna 12, a first transmitting/receiving switcher 20 connected to the diplexer 14 for switching a first transmitting system 16 and a first receiving system 18, and a second transmitting/receiving switcher 26 connected to the diplexer 14 for switching a second transmitting system 22 and a second receiving system 24. A first serial circuit 46 composed of a matching circuit 40, a SAW filter 42 in the unbalanced output system and an unbalanced/balanced converting circuit 44 is connected to the first receiving system 18, and a second serial circuit 56 composed of a matching circuit 50, a SAW filter 52 in the unbalanced output system and an unbalanced/balanced converting circuit 54 is connected to the second receiving system 24. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter / receiver in which transmission of two or more types of transmission signals and input of two or more types of reception signals can be shared by, for example, a single antenna device.

[0002]

2. Description of the Related Art Recently, a system with two frequency bands has become one.
Mobile communication and mobile phones covered by one antenna have been put into practical use. For example, in Europe 900 GSM (900
MHz) and 1800 DCS (1.8 GHz), in the United States 900 D-AMPS (900 MHz) and 1900 PCS
(1.9 GHz), 800 PDC (800 MH in Japan
z) and 1900 PHS (1.9 GHz).

In order to cover these two frequency bands with one antenna, a transmitter / receiver 10 as shown in FIG.
0 is used (for example, Japanese Patent Laid-Open No. 2001-211097).
(See the official gazette).

The transmitting / receiving apparatus 100 has an antenna 102.
Diplexer 104 connected to the diplexer 104 and the diplexer 1
No. 04, a first transmission / reception switch 106 for switching transmission / reception of signals in a first frequency band, and the diplexer 1
04, and a second transmission / reception switch 108 that switches transmission / reception of a signal in the second frequency band. Also, the first
Also, low-pass filters 110 and 112 are connected to the respective transmission sides of the second transmission / reception switchers 106 and 108.

The first low-pass filter 110 has a first
Of the transmission signal S11 of the second frequency band is input to the other low-pass filter 112.
3 is input.

A matching circuit 114 and a balanced output type SAW filter 116 are connected to the subsequent stage of the first transmission / reception switch 106, and the SAW filter 116 outputs a reception signal S12 in the first frequency band as shown in the figure. Not input to the balanced input type low noise amplifier in the subsequent stage.

A matching circuit 118 and a balanced output type SAW filter 120 are connected to the latter stage of the second transmission / reception switch 108. The SAW filter 120 outputs a reception signal S14 in the second frequency band, as shown in the figure. Not input to the balanced input type low noise amplifier in the subsequent stage.

[0008]

By the way, the SAW filters 116 and 120 connected to the respective receiving systems are required to be connected to the balanced input type low noise amplifiers in the subsequent stages, and therefore, the balanced output type SAW filters 116 and 12 are used together.
I am trying to use 0. However, the SAW filter of the balanced output type generally has poorer characteristics than the SAW filter of the unbalanced output type, and the reception characteristic of the signal may be deteriorated.

The present invention has been made in consideration of the above problems, and it is possible to use a SAW filter of an unbalanced output type having good characteristics and to suppress deterioration of signal reception characteristics. The purpose is to provide a device.

[0010]

A transmitting / receiving apparatus according to the present invention is connected to an antenna, and has a demultiplexing circuit for transmitting and receiving signals of at least two kinds of frequency bands, and one input / output terminal of the demultiplexing circuit. A first transmission / reception switch, which is connected and switches between a first transmission system and a first reception system, and a second transmission system and a second reception system which are connected to the other input / output terminal of the branching circuit. And a second transmission / reception switch for switching between the first and second reception systems, and at least an unbalanced output SAW
The filter and the unbalanced-balanced conversion circuit are connected in series, respectively.

As a result, the unbalanced output type SAW filter having excellent characteristics can be used for the receiving system (including the first and second receiving systems), and the deterioration of the signal receiving characteristics can be suppressed. .

The transmitter / receiver comprises at least a ceramic substrate and electronic components mounted on the surface of the ceramic substrate.
The transmission / reception switching device and the circuit element forming the second transmission / reception switching device may be incorporated.

In this case, the unbalanced-balanced conversion circuit is
It may be formed in the ceramic substrate. In this configuration, among the ceramic substrates, the unbalanced-
It is preferable that the dielectric constant of the portion forming the balance conversion circuit is 50 or more.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a transmitting / receiving apparatus according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the transmitting / receiving apparatus 10 according to the present embodiment is connected to an antenna 12, and has one diplexer 14 having first and second input / output terminals φ10 and φ11, and the diplexer 14. Connected to the first input / output terminal φ10 of the first transmission system 16 and the first reception system 1
8 is connected to the first input / output switch 20 and the second input / output terminal φ11 of the diplexer 14,
And a second transmission / reception switch 26 for switching between the transmission system 22 and the second reception system 24.

A transmission signal S11 in the first frequency band (for example, 800 MHz band) is input to the first transmission system 16, and a reception signal S12 in the 800 MHz band is input from the first reception system 18.
Is output. Further, the second transmission system 22 receives the transmission signal S13 in the second frequency band (for example, 1.8 GHz band), and the second reception system 24 outputs the reception signal S14 in the 1.8 GHz band. .

In particular, in order to improve the transmission characteristics, the first
And the second transmission systems 16 and 22 respectively include low-pass filters (first and second low-pass filters 30 and 3).
2) is connected. Therefore, the transmission signal S11 in the 800 MHz band is input to the first low-pass filter 30, and the 1.8-MHz transmission signal S11 is input to the second low-pass filter 32.
The transmission signal S13 in the GHz band is input.

In the first receiving system 18, the matching circuit 40, the unbalanced output type SAW filter 42 and the unbalanced-
First series circuit 46 by balance conversion circuit (balun) 44
From the first series circuit 46,
The reception signal S12 in the z band is output and input to a balanced input type low noise amplifier (not shown) in the subsequent stage.

To the second receiving system 24, a matching circuit 50, an unbalanced output type SAW filter 52, and a second series circuit 56 including an unbalanced-balanced conversion circuit (balun) 54 are connected. The 1.8 GHz band reception signal S14 is output from the series circuit 56 and input to a balanced input type low noise amplifier (not shown) in the subsequent stage.

Here, one experimental example will be shown. In this experimental example, changes in attenuation amount with respect to insertion loss of a balanced output type SAW filter and an unbalanced output type SAW filter are observed.

The experimental results are shown in FIG. In FIG. 2, the plots indicated by ■ and □ are SAWs of the unbalanced output method.
The characteristics of the filter, and the plots indicated by ● and ○ are the characteristics of the SAW filter of the balanced output method. From this result, the amount of attenuation at the same insertion loss is SA of the unbalanced method.
The number of balanced SAW filters is smaller than that of W filters, and it can be seen that the unbalanced SAW filters are better than the balanced SAW filters in terms of characteristics.

As described above, in the transmitting / receiving apparatus 10 according to this embodiment, the first and second receiving systems 18 and 24 are provided.
In addition, since it is possible to use the SAW filters 42 and 52 of the unbalanced output type having good characteristics, it is possible to suppress deterioration of the signal reception characteristics.

Various methods can be considered for mounting the first series circuit 46 and the second series circuit 56. Representatively, an example of a specific mounting method for the first series circuit 46 is shown in FIG. -It demonstrates, referring FIG. The same applies to the second series circuit 56.

(1) As shown in FIG. 3, a single electronic component 60 having a dielectric substrate on which a matching circuit 40 is formed, and a single electronic component 60 having a dielectric substrate on which an unbalanced output type SAW filter 42 is formed. Single electronic component 6 having one electronic component 62 and a dielectric substrate on which the unbalanced-balanced conversion circuit 44 is formed.
4 are mounted on a ceramic substrate 66, for example.

(2) As shown in FIG. 4, a composite electronic component 68 having a dielectric substrate on which the matching circuit 40 and the SAW filter 42 are formed, and a dielectric substrate on which the unbalanced-balanced conversion circuit 44 is formed. The single electronic component 64 having the same is mounted on the ceramic substrate 66.

(3) As shown in FIG. 5, a single electronic component 60 having a dielectric substrate on which a matching circuit 40 is formed, and S
The AW filter 42 and the composite electronic component 70 having the dielectric substrate on which the unbalanced-balanced conversion circuit 44 is formed are mounted on the ceramic substrate 66.

(4) As shown in FIG. 6, a composite electronic component 72 having a dielectric substrate on which the matching circuit 40 and the unbalanced-balanced conversion circuit 44 are formed, and a dielectric substrate on which the SAW filter 42 is formed. The single electronic component 62 having the same is mounted on a ceramic substrate 66.

(5) As shown in FIG. 7, the matching circuit 40,
The composite electronic component 74 having the dielectric substrate on which the SAW filter 42 and the unbalanced-balanced conversion circuit 44 are formed is mounted on the ceramic substrate 66.

Of these mounting methods, the method shown in (5) is one composite electronic component 74 on the ceramic substrate 66.
It is possible to configure one receiving system (in this case, the first receiving system 18) simply by implementing. The same applies to the second receiving system 24. As described above, by adopting the method shown in (5), first, component mounting becomes easy. Moreover, since the space between the parts can be saved, the size of the entire transmission / reception device 10 can be further reduced, and the manufacturing cost can be reduced.

In the various mounting methods described above, the circuit elements constituting the first transmission / reception switching device 20 and the second transmission / reception switching device 26 may be incorporated in the ceramic substrate 66. Further, the unbalanced-balanced conversion circuit 44 (balun) may be incorporated in the ceramic substrate 66. Of course, the same applies to the second receiving system 24. By adopting these configurations, the size of the transmission / reception device 10 can be further reduced.

The shape of the balun, which is the unbalanced-balanced conversion circuit 44, is determined by the wavelength. Therefore, Balun 4
In order to reduce the size of the balun 4, the balun 44 is formed among the various dielectric substrates and the ceramic substrate 66 (when the balun 44 is incorporated) forming the single electronic component 64 and the composite electronic components 70, 72 and 74. It is preferable that the dielectric constant of the portion to be 50 or more. Of course, the same applies to the balun 54 of the second receiving system 24.

The transmitting / receiving apparatus according to the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0033]

As described above, according to the transmitting / receiving apparatus of the present invention, it is possible to use the SAW filter of the unbalanced output type having good characteristics, and it is possible to suppress the deterioration of the signal reception characteristics. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmitting / receiving apparatus according to the present embodiment.

FIG. 2 is a characteristic diagram showing changes in attenuation amount with respect to insertion loss of a balanced output type SAW filter and an unbalanced output type SAW filter.

FIG. 3 is an explanatory diagram showing a first example of a mounting method of the first series circuit.

FIG. 4 is an explanatory diagram showing a second example of the mounting method of the first series circuit.

FIG. 5 is an explanatory diagram showing a third example of a mounting method of the first series circuit.

FIG. 6 is an explanatory diagram showing a fourth example of a mounting method of the first series circuit.

FIG. 7 is an explanatory diagram showing a fifth example of a mounting method of the first series circuit.

FIG. 8 is a block diagram showing a configuration of a transmission / reception device according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Transceiver 12 ... Antenna 14 ... Diplexer 16 ... 1st transmission system 18 ... 1st reception system 20 ... 1st transmission / reception switch 22 ... 2nd transmission system 24 ... 2nd reception system 26 ... 2nd Unbalanced output type SAW filter 44 ... Unbalanced-balanced conversion circuit (balun) 46 ... First series circuit 50 ... Matching circuit 52 ... Unbalanced output type SAW filter 54 ... Unbalanced-balanced Conversion circuit (balun) 56 ... Second series circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Miyazawa             664-1 Sarukubo, Saku City, Nagano Prefecture Soshin Electric Co., Ltd.             Ceremony Company Chikuma Factory F-term (reference) 5K011 DA21 DA27 EA01 JA01 KA05                       KA18

Claims (4)

[Claims] 1. A demultiplexing circuit which is connected to an antenna and which allows transmission / reception signals of at least two kinds of frequency bands to pass, and one input / output terminal of the demultiplexing circuit, which is connected to a first transmission system and a first transmission system. A first transmission / reception switcher for switching between the reception system and a second transmission / reception switcher connected to the other input / output terminal of the demultiplexing circuit for switching between the second transmission system and the second reception system. And at least an unbalanced output S is applied to the first and second receiving systems.
A transmitter / receiver characterized in that an AW filter and a series circuit of an unbalanced-balanced conversion circuit are connected to each other. 2. The transmitter / receiver according to claim 1, wherein the transmitter / receiver includes at least a ceramic substrate and electronic components mounted on the surface of the ceramic substrate.
A transmission / reception device characterized in that circuit elements constituting the first transmission / reception switching device and the second transmission / reception switching device are incorporated in the ceramic substrate. 3. The transmitter / receiver according to claim 2, wherein the unbalanced-balanced conversion circuit is formed in the ceramic substrate. 4. The transmitter / receiver according to claim 3, wherein a portion of the ceramic substrate that constitutes the unbalanced-balanced conversion circuit has a dielectric constant of 50 or more.