JP2003298481A - Communication equipment, filter circuit, and diversity detection circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide communication equipment at a reduced cost with a small- sized configuration in the case of employing the after-detection diversity reception. <P>SOLUTION: A mobile phone is provided with: two antennas 31, 41 for receiving signals; two systems of detection circuits 61, 62 for detecting the signals received by the two antennas 31, 41; and a configuration after a digital signal processing section 11 for restoring a signal sent from a communication opposite party. The two systems of the detection circuits 61, 62 use power splitters 35, 45 to distribute/compose intermediate frequency signals for sharing one intermediate frequency filter 39. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device for signal communication, a filter circuit for band limiting an input signal, and a diversity detection circuit for detecting a modulated wave received by a diversity antenna.

[0002]

2. Description of the Related Art Conventionally, in the field of wireless communication, a diversity reception system has been adopted as one of effective methods for countering fading. In particular, in the case of mobile communication using a mobile phone or the like, the diversity reception system is said to be effective because the propagation path of radio waves changes with time as the mobile terminal moves.

In recent years, there has been an increasing demand for higher speed wireless communication. In particular, mobile communication systems using mobile phones provide multimedia services for handling various contents such as voice, data, and moving images in the third generation following the analog first generation and the digital second generation. Higher communication speed is required to provide high quality.

Here, in the diversity reception system in the case where the communication speed of wireless communication is increased, after extracting a modulated signal component (hereinafter referred to as a received signal) from a modulated wave signal received by a plurality of antennas, A method of selecting a reception signal with the best reception state, that is, a diversity reception method after detection is suitable.

[0005]

However, the post-detection diversity reception system requires a plurality of independent detection circuits corresponding to a plurality of antennas, which inevitably increases the cost of the receiver. Further, a receiver including a plurality of detection circuits has a problem that the configuration becomes large. In particular, since a mobile phone is greatly required to be small and lightweight, it is not preferable to increase the size of the structure.

The present invention has been made in view of the above problems, and in the case of performing diversity reception after detection, the communication device, the filter circuit, and the communication device which reduce the cost and also realize the downsizing of the structure. An object is to provide a diversity detection circuit.

[0007]

A communication apparatus of the present invention comprises one filter means for band limiting a received signal, guides the received signals of at least two systems to one filter means, and the band limiting by the filter means. A signal having a good reception state is selected from the latter two reception signals, and the signal transmitted by the communication partner is restored from the selected signal.

The filter circuit of the present invention guides an input signal to one input / output terminal of one filter having no directivity in input / output characteristics, and at the same time, outputs a signal output from one input / output terminal of the filter. Signal input / output means for extracting as an output signal is provided on both input / output ends of the filter.

The diversity detection circuit of the present invention amplifies the high frequency signal received by the two diversity antennas,
Each band-limited signal is converted to an intermediate-frequency signal, the two intermediate-frequency signals are band-limited by a shared intermediate-frequency filter, the signal level is controlled, and the band-limited signal is converted to a baseband signal for detection. I do.

That is, according to the present invention, one filter is shared by two detection circuits.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiments of the present invention, a third-generation mobile phone is cited as an example of a communication device to which the present invention is applied. FIG. 1 shows a schematic configuration of an internal circuit 10 of the mobile phone according to the present embodiment. The mobile phone shown in FIG. 1 adopts a post-detection diversity reception system suitable for, for example, third-generation high-speed communication.

Further, in the portable telephone, the cost is reduced by sharing a particularly expensive element or an element which is difficult to be miniaturized and integrated into an IC, among the elements constituting the plurality of detection circuits, by the plurality of detection circuits. And the downsizing of the configuration has been realized. Figure 1
The mobile phone shown in (1) is an example of an element commonly used for the SAW (surface acoustic wave) filter, which is expensive and difficult to miniaturize.

[Explanation of Internal Configuration of Mobile Phone] FIG.
In, the antennas 31 and 41 are diversity antennas. The high frequency modulated wave signal (hereinafter referred to as an RF signal) received by the antenna 31 is detected by the detection circuit 61.
Is input to the LNA (Low Noise Amp) 32. LNA
The RF signal amplified by 32 is input to the high frequency filter 33.

The high frequency filter 33 is a band pass filter having a pass band in the frequency band of the modulated wave. The RF signal whose band is limited by the high frequency filter 33 is input to the frequency converter 34.

The frequency converter 34 converts the RF signal into an intermediate frequency signal (hereinafter referred to as an IF signal). This IF signal is input to the power splitter 35.

The power splitter 35 distributes the signal input from the A side in the figure with low loss in the B direction and high loss (high attenuation) in the F direction, while the signal input from the B side in the figure is distributed. , A direction and B direction are evenly distributed. Therefore, almost all of the IF signals from the frequency converter 34 are transmitted in the B direction in the figure.
This IF signal is input to the intermediate frequency filter 39.

On the other hand, the RF signal received by the antenna 41 is sent to the LN of the detection circuit 62 via the antenna duplexer 50.
Input in A42. This RF signal is amplified by the LNA 42, band-limited by the high-frequency filter 43, and further converted into an IF signal by the frequency converter (intermediate frequency converter) 44. This IF signal is input to the power splitter 45.

The power splitter 45 distributes the signal input from the E side in the figure with low loss in the D direction and high loss in the C direction, while the signal input from the C side in the figure is changed to the E direction. It has the characteristic of being uniformly distributed in the D direction. Therefore, almost all the IF signals from the frequency converter (intermediate frequency converter) 44 are transmitted in the C direction in the figure. This IF signal is input to the intermediate frequency filter 39. The detailed configurations of the power splitters 35 and 45 will be described later.

The intermediate frequency filter 39 is a bandpass filter whose pass band is the frequency band of the IF signal, and is composed of a SAW filter having low loss and high response characteristics. Further, the filter 39 is a filter having no directivity in input / output characteristics.

Therefore, the IF signal transmitted from the A side in the figure through the power splitter 35 in the B direction is input to the power splitter 45 after the intermediate frequency band is limited by the intermediate frequency filter 39. Become. At this time, the power splitter 45 sends the IF signal to D in the figure.
Evenly distributed in the direction and E direction. The IF signal distributed in the D direction is automatically variable gain amplifier (hereinafter referred to as AGC).
46). The signal distributed in the E direction is sent to the output terminal of the frequency converter 44, but since the frequency converter 44 has an input characteristic in only one direction from the input terminal side, It doesn't matter here.

On the other hand, the IF signal transmitted from the E side to C direction in the figure through the power splitter 45 is band-limited by the intermediate frequency filter 39, and then input to the power splitter 35. At this time, the power splitter 45 evenly distributes the IF signal in the F and A directions in the figure. Then, the IF signal distributed in the F direction is input to the AGC amplifier 36. The signal distributed in the A direction is sent to the output terminal side of the frequency converter 34, but the frequency converter 34 has an input characteristic in only one direction from the input side terminal side. So it doesn't matter here.

As described above, the mobile phone of FIG. 1 has a structure in which the intermediate frequency filter 39, which is an expensive and difficult to miniaturize SAW filter, is shared in the reception path of the antenna 31 and the reception path of the antenna 41. ing.
That is, when the intermediate frequency filters are separately used in the two detection circuits, two SAW filters must be provided. However, in the mobile phone of FIG. 1, the detection circuits 61 and 6 are used.
By sharing the intermediate frequency filter 39 with S2,
There is one AW filter.

The IF signal transmitted from the B side in the figure in the F direction through the power splitter 35 is adjusted to a predetermined level by the AGC amplifier 36 and then input to the frequency converter 37. The AGC amplifier 36 is provided in order to make the input signal level to the digital signal processing unit 11 in the subsequent stage constant. The frequency converter 37 converts the IF signal into a baseband signal. Then, the baseband signal is input to the digital signal processing unit 11 after the baseband band is limited by the baseband filter 38.

The IF signal transmitted from the C side in the figure in the D direction through the power splitter 45 is adjusted to a predetermined level by the AGC amplifier 46, and then is adjusted by the frequency converter (baseband converter) 47. Converted to baseband signal. Then, the baseband signal is band-limited by the baseband filter 48 and then input to the digital signal processing unit 11.

The digital signal processing unit 11 receives the baseband signals from the baseband filters 38 and 48, that is, the antennas 31 and 41, and further detects the detection circuit 6.
Of the received signals detected by 1 and 62, the signal in the better receiving state is selected. Then, the digital signal processing unit 11 reproduces the data sequence transmitted by the communication partner by performing processing such as despreading, deinterleaving, and error correction decoding of the received signal. In addition, the digital signal processing unit 1
1 discriminates the reproduced data sequence into voice data and other communication data.

The voice data is digital-to-analog converted (D / A converted) by the digital signal processing unit 11, further amplified by an amplifier (not shown), and then the speaker 17.
Sent to. The speaker 17 is driven by the amplified analog audio signal. As a result, the call voice from the terminal of the other party of the call is emitted from the speaker 17.

Further, the digital signal processing section 11 analyzes what kind of data the communication data is, and performs processing according to the analysis result. For example, when the communication data is text data, the digital signal processing unit 11 sends the text data to the control unit 22. At this time, the control unit 22 sends the text data to the display unit 23 for display. In addition, for example, when the communication data is compressed image data, the digital signal processing unit 11 decompresses the compressed image data and sends the compressed image data to the control unit 22. At this time, the control unit 22 sends the image data to the display unit 23 for display. Further, for example, when the communication data is compressed sound data, the digital signal processing unit 11 expands the compressed sound data and outputs it to the speaker 15 or 17.

In addition, when the call information is detected, the digital signal processing section 11 generates a ring tone signal in response to the detection of the call information. The ring tone signal is amplified by an amplifier (not shown) and then sent to the speaker 15. The speaker 15 is driven by the amplified ring tone signal. As a result, the ringing tone corresponding to the call information is emitted from the speaker 15.

The microphone 16 converts a user's call voice or the like into an electric signal (that is, an analog voice signal).
The analog voice signal of the call voice is input to the digital signal processing unit 11 after being amplified by an amplifier (not shown).

At this time, the digital signal processing unit 11 performs analog / digital conversion of the analog audio signal at a predetermined sampling rate, and further performs error correction coding, interleaving, spreading processing, etc. on the digital audio data. . The signal after this spreading processing is transmitted by the transmission circuit 63.
Input to the baseband filter 51.

The base band filter 51 limits the base band of the signal from the digital signal processing section 11. The baseband signal output from the baseband filter 51 is sent to the frequency converter 52.

The frequency converter 52 converts the baseband signal into an IF signal and sends the IF signal to the AGC amplifier 53. The AGC amplifier 53 adjusts the IF signal to a predetermined level and sends it to the intermediate frequency filter 54. The intermediate frequency filter 54 band-limits the IF signal and sends it to the frequency converter 55. The frequency converter 55 has an IF
The signal is converted into an RF signal and sent to the high frequency filter 56. The RF signal subjected to band limitation by the high frequency filter 56 is amplified by the transmission amplifier 57 and then transmitted from the antenna 41 via the antenna duplexer 50.

A ROM (Read Only Memory) 21 stores a control program for the control unit 22 to control each unit, various initial setting values, font data, and the like. The ROM 21 is an EEPROM (Electrically E
It may be a rewritable ROM such as a rasable and Programmable Read Only Memory).

A RAM (Random Access Memory) 20 is
Data is stored as needed as a work area when the control unit 22 performs various types of data processing.

The operation unit 19 is various keys and buttons operated by the user. The operation signal generated by the operation unit 19 according to the user's operation is input to the control unit 22.

The control unit 22 controls the operation of each unit based on a control program and operation signals stored in the ROM 21, and also performs various arithmetic processes.

Short-range wireless communication section 24 and its antenna 25
Is for performing so-called Bluetooth wireless communication. The Bluetooth method is a method for realizing ad hoc wireless networking between a plurality of electronic devices. This Bluetooth method is based on the Bluetooth SIG (Special Interest Group
It was formulated by p.), and the details are "Bluetooth (T
M) Special Interest Group, Bluetooth specification version 1.0 ".

[Specific Configuration Example of Power Splitter] FIG.
Shows a specific configuration example of the power splitters 35 and 45. The power splitters 35 and 45 have the same configuration.

The power splitter shown in FIG. 2 has a general Wilkinson type configuration, and is composed of three input / output ports 71, 75 and 76, an absorption resistor 74 and two strip lines 72 and 73. It is configured.

The input / output port 71 is the strip line 7
Commonly connected to one end of 2 and 73. The input / output port 75 is connected to the other end of the strip line 72, and the input / output port 76 is connected to the other end of the strip line 73.

The strip lines 72 and 73 have characteristics of impedance R and length λ / 4 (λ is wavelength), respectively, and are provided as a pattern on a circuit board by a distributed constant, for example. The strip line 72,
73 may be realized by a lumped constant.

The absorption resistor 74 has one end connected to the input / output port 75 and the other end connected to the input / output port 76.

Therefore, in the power splitter of FIG. 2, the signal input from the input / output port 75 is output from the input / output port 71 via the strip line 72 with low loss. The signal input from the input / output port 76 is
Input / output port 7 with low loss via strip line 73
It is output from 1. On the other hand, since a signal is absorbed between the input / output port 75 and the input / output port 76 by the absorption resistor 74, high isolation is realized.

The signal input from the input / output port 71 is evenly distributed, passes through the strip lines 72 and 73, and is output from the input / output ports 75 and 76.

In the power splitter 35 of FIG. 1, the input / output port on the A side in FIG. 1 corresponds to the input / output port 75 of FIG. 2, for example, and the input / output port on the F side is the input / output port 76 of FIG.
The B side input / output port corresponds to the input / output port 7 in FIG.
Corresponds to 1. The input / output port on the A side in FIG. 1 may correspond to the input / output port 76 in FIG. 2, and the input / output port on the F side may correspond to the input / output port 75 in FIG.

In the power splitter 45 of FIG. 1, the input / output port on the E side in FIG. 1 corresponds to the input / output port 75 of FIG. 2, for example, and the input / output port on the D side is the input / output port 76 of FIG. The input / output port on the C side corresponds to the input / output port 71 in FIG. The input / output port on the E side in FIG. 1 may correspond to the input / output port 76 in FIG. 2, and the input / output port on the D side may correspond to the input / output port 75 in FIG.

Then, the power splitters 35 and 4 shown in FIG.
In FIG. 5, strip lines 72 and 73 of FIG. 2 are arranged as a pattern on the circuit board by a distributed constant. Therefore, the two power splitters 35 and 45 are
Very cheap. Further, the area occupied by these two power splitters 35 and 45 on the circuit board is smaller than the area occupied by one SAW filter on the circuit board.
Furthermore, the weight of these two power splitters 35 and 45 is much lighter than the weight of one SAW filter.

[Appearance of Mobile Phone] FIG. 3 shows an appearance of the mobile phone 1 of the present embodiment having the circuit configuration shown in FIG. 1 as viewed from the front.

In FIG. 3, the mobile phone 1 is
It is a foldable type (two-fold type), and is roughly divided into a key arrangement portion 8, a display arrangement portion 7, and a hinge portion 3.

The display arranging section 7 includes the display section 23.
The display 2 is provided. The display 2 is an LCD (Liquid Crystal Display) or EL.
It is composed of an (ElectroLuminescence) panel or the like, and can display at least a character, a number, a symbol, an icon, a cursor, and preferably a color moving image. In addition, the display arrangement unit 7 is internally provided with the speaker 17 of FIG. 1 which is used during a call and the like, and is also provided with a plurality of speaker holes 6 for outputting sound from the speaker 17 to the outside.

The key arrangement unit 8 corresponds to the operation unit 19 of FIG. 1, and at least inputs numbers from "0" to "9", alphabet characters, kana characters, and
A plurality of keys 4 used for inputting symbols, inputting instructions for converting kana to kanji, inputting instructions for sending and receiving, inputting instructions for turning power on / off, and the like are provided. Also, the key placement unit 8
1 has therein the microphone 16 of FIG. 1 used during a call, and also has a microphone hole 5 for the microphone 16 to collect voice.

The hinge portion 3 has a structure capable of opening and closing the key arrangement portion 8 and the display portion 7 within a range of approximately 0 to 180 degrees. In FIG. 3, the opening / closing angle of the hinge portion 3 is approximately 1
The state is set to 80 degrees. When the opening / closing angle of the hinge portion 3 is set to approximately 0 degrees, in the mobile phone 1, the surface of the key arrangement portion 8 on which the keys 4 are provided and the surface of the display arrangement portion 7 that faces the display 2 face each other. It will be in the folded state.

[Summary of Embodiments] As described above, the mobile phone according to the present embodiment has two detection circuits 6.
By sharing the intermediate frequency filter 39 in the Nos. 1 and 62, the number of expensive and difficult to miniaturize SAW filters can be suppressed to one, and as a result, cost reduction can be realized and the circuit board It is also possible to reduce the size and weight.

The above description of the embodiment is an example of the present invention. Therefore, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made according to the design and the like as long as they do not depart from the technical idea of the present invention. . For example, the element shared by the detection circuits is not limited to the intermediate frequency filter and may be a high frequency filter. Moreover, the number of diversity antennas is not limited to two, and the number of detection circuits is not limited to two. Furthermore, the communication device of the present invention is not limited to a mobile phone, and can be applied to any communication device as long as it has a detection circuit corresponding to each of a plurality of diversity antennas such as a diversity reception system after detection. .

[0055]

According to the present invention, one filter means is shared to limit the band of received signals of at least two systems, so that, for example, in the diversity reception system after detection,
The cost can be reduced as compared with the case where a filter is provided in each of the detection circuits of the system, and further, the configuration can be downsized.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of an internal circuit of a mobile phone according to an embodiment.

FIG. 2 is a circuit diagram showing a specific configuration of a power splitter.

FIG. 3 is an external view of a mobile phone.

[Explanation of symbols]

1 ... Mobile phone, 2 ... Display, 3 ... Hinge part, 4
... keys, 5 microphone holes, 6 ... speaker holes, 7 ... display arranging section, 8 ... key arranging section, 10 ... internal circuit, 11 ... digital signal processing section, 15, 17 ... speaker, 16 ... microphone, 19 ... operating section , 20 ... RAM, 21 ... RO
M, 22 ... Control unit, 23 ... Display unit, 31, 41 ... Antenna, 32, 42 ... LNA, 33, 43, 56 ... High frequency filter, 34, 37, 44, 52, 55 ... Frequency converter, 35, 45 ... power splitter, 39, 54 ... intermediate frequency filter, 36, 46, 53 ... AGC amplifier, 3
8, 48, 51 ... Base band filter, 72, 73 ...
Strip line, 74 ... Absorption resistance

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5K022 EE04 EE35                 5K059 CC03 DD02 DD16 DD25 EE02                       EE03                 5K067 AA42 BB04 CC24 DD43 EE02                       KK03

Claims (6)

[Claims] 1. A filter means for band-limiting a received signal, a signal guide means for guiding at least two systems of received signals to the one filter means, and two systems of received signals after band limitation by the filter means. From the selected signal, and a signal restoration unit that restores the signal transmitted by the communication partner from the selected signal. 2. The communication device according to claim 1, wherein a first signal processing unit which performs a first process on the received signal before band limitation by the filter means, and a band signal after the band limitation by the filter means. And a second signal processing unit for performing the second processing on the received signal of 1) are provided for each system, and the signal guiding means guides the signal after the first processing of one system to the filter means at the same time. , First of the other system
The communication device, which guides the signal after the signal after the process of (1) is band-limited by the filter means to the second process of the one system. 3. The communication device according to claim 2, further comprising: at least two diversity antennas for receiving signals, one system of first and second signal processing units, and the one filter means. A communication device comprising: a detection circuit configured to detect a reception signal for one system. 4. One filter means having no directivity in input / output characteristics, and guiding an input signal to one input / output terminal of the filter and at the same time outputting a signal output from one input / output terminal of the filter. A first signal input / output unit for extracting as an output signal and a second signal input / output unit for extracting the signal output from the other input / output end of the filter as an output signal while guiding the input signal to the other input / output end of the filter. A filter circuit comprising a signal input / output unit. 5. The filter circuit according to claim 4, wherein the first and second signal input / output means have three input terminals, an input signal side terminal, an output signal side terminal and the filter side terminal. Each output terminal has a high attenuation from the input signal side terminal to the output signal side terminal, a low loss signal from the input signal side terminal to the filter side terminal, and from the filter side terminal to the input signal side. A filter circuit having a characteristic that a signal is evenly distributed to the terminals of and the terminals on the output signal side. 6. A first and a second diversity antenna for receiving a signal, a first amplifier for amplifying a high frequency signal received by the first diversity antenna, and a second diversity. A second amplifier for amplifying a high frequency signal received by an antenna, a first high frequency filter for band limiting the high frequency signal after amplification by the first amplifier, and an amplification by the second amplifier A second high frequency filter for band limiting the subsequent high frequency signal; a first intermediate frequency converter for converting the high frequency signal band limited by the first high frequency filter into an intermediate frequency signal; A second intermediate frequency converter for converting a high frequency signal band-limited by the second high frequency filter into an intermediate frequency signal; One intermediate frequency filter for performing band limitation on the frequency signal, the intermediate first to control the level of band-limited intermediate frequency signal constant by a frequency filter, a second 2
Two variable gain amplifiers, and a first variable gain amplifier for converting an intermediate frequency signal whose level is controlled by the first variable gain amplifier into a baseband signal.
A second baseband converter for converting an intermediate frequency signal, the level of which is controlled by the second variable gain amplifier, into a baseband signal.
A baseband converter, a first baseband filter for band limiting the baseband signal from the first baseband converter, and a baseband signal from the second baseband converter. And a second baseband filter for guiding the intermediate frequency signal from the first intermediate frequency converter to the intermediate frequency filter, and at the same time the intermediate frequency signal from the second intermediate frequency converter is converted into the intermediate frequency filter. First signal guiding means for guiding the band-limited signal to the first variable gain amplifier, and the intermediate frequency signal from the second intermediate frequency converter to the intermediate frequency filter, and at the same time, The intermediate frequency signal from the first intermediate frequency converter is band-limited by the intermediate frequency filter to the second variable gain amplifier. A diversity detection circuit comprising: a second signal guiding means for guiding.