JP2015019432A - Communication module, on-vehicle device, and mobile communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress spurious to an ECT signal band radiated from an antenna 12 by making the spurious to the ETC signal band output from a PA (86) mismatch at an antenna connection circuit (42).SOLUTION: In a communication module 10 of an on-vehicle device 100, a telephone signal in a 2-GHz band is amplified by a PA (86), and output from a triplexer (44) to an antenna 12 via an antenna connection circuit (42). Then, the 2-GHz band telephone signal is transmitted from the antenna 12. When the telephone signal is transmitted, spurious to an ETC signal band may be output from the PA (86), and may directly go into the triplexer (44). Therefore, the antenna connection circuit (42) provided between the antenna 12 and the triplexer (44) is set to match at a frequency band of the telephone signal including the 2-GHz band, and mismatch at a frequency band of an ETC signal including 5.83 GHz.

Description

  The present invention relates to a communication module, an in-vehicle device, and a mobile communication terminal, and more particularly to a communication module, an in-vehicle device, and a mobile communication terminal that are mounted on a vehicle such as an automobile and transmit / receive a signal of a mobile phone, for example.

  In an in-vehicle device provided with this type of communication module, it is necessary not to adversely affect an ETC (Electronic Toll Collection) signal (hereinafter referred to as “ETC signal”).

On the other hand, Patent Document 1 discloses a high-frequency signal switching device. In this device, a high frequency signal generated from a PIN diode is blocked by a transmission side and reception side matching circuit.
JP 2002-271104 A [H01P 1/15, H04B 1/50]

  The high-frequency signal switching device disclosed in Patent Document 1 can only deal with a high-frequency signal at the time of switching the PIN diode, and does not take into consideration the influence on the ETC.

  Therefore, a main object of the present invention is to provide a novel communication module, in-vehicle device, and portable communication terminal.

  Another object of the present invention is to provide a communication module, an in-vehicle device, and a portable communication terminal that can suppress spuriousness of the ETC signal to the frequency band as compared with the related art.

  The present invention employs the following configuration in order to solve the above problems.

  According to a first aspect of the present invention, there is provided a communication module including a duplexer that outputs a signal amplified by an amplifier and an antenna that transmits a signal output from the duplexer, and an antenna connection circuit between the antenna and the duplexer. In the antenna connection circuit, matching is performed in a frequency band including a predetermined frequency used for communication with the base station, and mismatching is performed in a frequency band of an ETC signal including a harmonic of the predetermined frequency or a nearby frequency of 5.8 GHz. It is the communication module characterized by setting so that it may become.

  The second invention is dependent on the first invention, and the frequency band including the predetermined frequency is a 2 GHz band.

  A third invention is an in-vehicle device including the communication module of the first invention or the second invention.

  According to a fourth aspect of the present invention, there is provided a duplexer that outputs a signal amplified by an amplifier, an antenna that transmits a signal output from the duplexer, and a communication between the antenna and the duplexer, and communication with a base station. And an antenna connection circuit that is set so as to be matched in a frequency band including a predetermined frequency and used in a frequency band of an ETC signal including a harmonic of the predetermined frequency or in the vicinity of 5.8 GHz. It is a communication terminal.

  A fifth invention is dependent on the fourth invention, and further includes a display unit and a display control unit that displays a map image on the display unit.

  A sixth invention is dependent on the fourth invention or the fifth invention, and the frequency band including the predetermined frequency is a 2 GHz band.

  According to the present invention, spurious to the frequency band of the ETC signal can be suppressed as compared with the prior art.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

FIG. 1 is an illustrative view showing an electrical configuration of an in-vehicle device according to an embodiment of the present invention. FIG. 2 is an illustrative view showing an example of the configuration of the wireless communication circuit shown in FIG. 1 and its surroundings. FIG. 3 is an illustrative view showing one example of a configuration of the antenna connection circuit shown in FIG. 2. FIG. 4 is an illustrative view showing one example of a Smith chart obtained by measuring between the antenna and the antenna connection circuit shown in FIG. 2 and between the triplexer and the duplexer for the 2 GHz band.

  Referring to FIG. 1, an in-vehicle device 100 according to an embodiment of the present invention is a kind of mobile communication terminal that can be realized as a navigation system, for example, and includes a communication module 10, an antenna 12, and a user interface unit 14. The communication module 10 includes a wireless communication circuit 16, a processor 18, a flash memory 20, a RAM 22, and a power supply circuit 24. A wireless communication circuit 16, a flash memory 20, a RAM 22, and a power supply circuit 24 are connected to a processor 18 called a CPU. The antenna 12 connected to the communication module 10 is connected to the wireless communication circuit 16 in the communication module 10.

  The user interface unit 14 includes a microphone 30, a speaker 32, a key input device 34, a display driver 36, and a display 38. A display 38 is connected to the display driver 36.

  A microphone 30, a speaker 32, a key input device 34, and a display driver 36 included in the user interface unit 14 are connected to the processor 18 of the communication module 10.

  The processor 18 governs overall control of the in-vehicle device 100. The RAM 22 is used as a work area (including a drawing area) or a buffer area of the processor 18. Application data is recorded in the flash memory 20.

  The power supply circuit 24 is an IC for power management, and is connected to an external power supply, and supplies power based on the external power supply to the wireless communication circuit 16, the processor 18, the flash memory 20, and the RAM 22. Here, when the power supply circuit 24 supplies power to the entire system, it is referred to as a power-on state. On the other hand, when the power supply circuit 24 is not supplying power to the entire system, it is referred to as a power-off state. The external power source is a 12V power source supplied from, for example, a vehicle cigar socket.

  The processor 18 includes an A / D converter and a D / A converter (both not shown). For this reason, the processor 18 converts an analog audio signal of audio or sound input through the microphone 30 into a digital audio signal by a built-in A / D converter. Further, the processor 18 converts (decodes) the digital audio signal into an analog audio signal by a built-in D / A converter, and supplies the analog audio signal to the speaker 32 via an amplifier (not shown). Therefore, sound or sound corresponding to the analog sound signal is output from the speaker 32. The processor 18 can adjust the volume of the sound output from the speaker 32 by controlling the amplification factor of the amplifier.

  The key input device 34 functions as an operation unit. Then, information (key data) of keys operated by the user is input to the processor 18.

  The display driver 36 controls display on the display 38 under the instruction of the processor 18. The display driver 36 also includes a video memory (not shown) that temporarily stores image data to be displayed.

  Further, the in-vehicle device 100 transmits a telephone signal of 800 MHz band (for example, reception band: 875 to 885 MHz) and 2 GHz band (for example, reception band: 2.10 to 2.170 GHz) transmitted from the mobile phone base station 200. Is received by the antenna 12. On the other hand, the in-vehicle device 100 is directed to the mobile phone base station 200 with telephone signals of 800 MHz band (for example, transmission band: 830 to 840 MHz) and 2 GHz band (for example, transmission band: 1.920 to 1.980 GHz). Is transmitted from the antenna 12. In addition, a GPS signal of 1575.42 MHz transmitted from the GPS satellite 300 is also received by the antenna 12. The processor 18 includes a GPS communication circuit (not shown), and can obtain the longitude and latitude by demodulating the received GPS signal. Thus, the antenna 12 of the present embodiment transmits or receives a telephone signal and receives a GPS signal.

  FIG. 2 is an illustrative view showing a configuration of the wireless communication circuit 16 and its periphery. The wireless communication circuit 16 includes an antenna connection circuit 42 connected to the antenna 12, a triplexer 44 for separating signals of 800 MHz band, 2 GHz band and GPS, and an RF circuit 40 for converting the frequency of signals to be transmitted and received in order to transmit and receive signals. Etc. are included.

  Since the triplexer 44 functions as a duplexer, it is connected to a duplexer 46 for the 800 MHz band, a duplexer 54 for the 2 GHz band, and a GPS-SAW (Surface Acoustic Wave) filter 64.

  For example, when a telephone signal, a GPS signal, or the like is received by the antenna 12, the triplexer 44 receives the received signal (reception signal) in each of the duplexer 46 for the 800 MHz band, the duplexer 54 for the 2 GHz band, and the GPS-SAW filter 64. ) Is output.

  The reception signal including the 800 MHz band telephone signal is output from the 800 MHz band duplexer 46 to the 800 MHz band balun coil 48. The balun coil 48 extracts a 800 MHz band telephone signal included in the received signal and outputs the telephone signal to the RF circuit 40.

  In the RF circuit 40, the 800 MHz band telephone signal is amplified by an LNA (Low Noise Amplifier) 50 and then output to a down converter 52. The down converter 52 lowers the frequency of the 800 MHz band telephone signal to a predetermined frequency to obtain a baseband signal, and then outputs the baseband signal to the processor 18. The processor 18 performs digital demodulation processing, error correction encoding processing, and audio encoding processing on the baseband signal. Then, the processor 18 converts the digital audio signal subjected to the audio encoding process into an analog audio signal and outputs the analog audio signal to the speaker 32.

  A reception signal including a 2 GHz band telephone signal is output from the 2 GHz band duplexer 54 to the first stage LNA 56 of the RF circuit 40. The received signal is amplified by the first stage LNA 56 and then output to the interstage SAW filter 58 for 2 GHz band provided outside the RF circuit 40. The interstage SAW filter 58 for 2 GHz band functions as a BPF (Band Pass Filter), and extracts a 2 GHz band telephone signal from the received signal. The extracted 2 GHz band telephone signal is input again to the RF circuit 40, amplified by the second-stage LNA 60, and then output to the down converter 62. The down converter 62 lowers the frequency of the 2 GHz band telephone signal to a predetermined frequency to obtain a baseband signal, and then outputs the baseband signal to the processor 18. The processor 18 similarly performs the above-described processing on the baseband signal, and outputs an analog audio signal to the speaker 32.

  Furthermore, when a reception signal including a GPS signal is output to the GPS-SAW filter 64, an unnecessary signal such as a telephone signal is removed from the reception signal. The signal output from the GPS-SAW filter 64 is amplified by the first stage LNA 66. Further, a GPS signal is extracted from the amplified received signal by the GPS-SAW filter 68 and output to the RF circuit 40. In the RF circuit 40, the GPS signal is amplified by the second-stage LNA 70, and the frequency of the GPS signal is lowered by the down converter 72. Then, the processor 18 obtains the longitude and latitude of the current position after performing demodulation processing and decoding processing on the GPS signal whose frequency has been lowered. At this time, when the map function is executed in the in-vehicle device 100, a map image with an icon indicating the current position is displayed on the display 38.

  On the other hand, the audio signal captured by the microphone 30 is subjected to audio encoding processing, error correction encoding processing, and digital modulation processing by the processor 18 to obtain a baseband signal. Thereafter, the baseband signal is output to either the 2 GHz band upconverter 80 or the 800 MHz band upconverter 90 of the RF circuit 40.

  When the baseband signal is output to the upconverter 80 for the 2 GHz band, the baseband signal is raised to the 2 GHz transmission band by the upconverter 80, amplified by the LNA 82, and then output from the RF circuit 40 to the SAW filter 84. Is done. The SAW filter 84 removes noise from the amplified telephone signal in the 2 GHz band and outputs it to a PA 86 (Power Amplifier). The PA 86 amplifies the 2 GHz band telephone signal from which noise has been removed, and outputs the amplified signal to the 2 GHz band duplexer 54 via the isolator 88. The duplexer 54 outputs a 2 GHz band telephone signal for transmission to the triplexer 44. Then, the triplexer 44 provides a 2 GHz band telephone signal to the antenna 12 via the antenna connection circuit 42. As a result, a 2 GHz band telephone signal is transmitted from the antenna 12.

  When the baseband signal is output to the upconverter 90 for the 800 MHz band, the baseband signal is raised to the 800 MHz transmission band by the upconverter 90. Thereafter, similarly to the 2 GHz band telephone signal, the 800 MHz band telephone signal is amplified by the LNA 92, noise is removed by the SAW filter 94, and then amplified again by the PA 96. The amplified 800 MHz band telephone signal is output to the 800 MHz band duplexer 46 via the isolator 98 and further to the triplexer 44. Then, the triplexer 44 gives an 800 MHz band telephone signal to the antenna 12 via the antenna connection circuit 42. Thereby, an 800 MHz band telephone signal is transmitted from the antenna 12.

  The isolator 88 and the isolator 98 are elements that allow only signals in one direction to pass therethrough so that the reflected wave from the antenna 12 side and the change in the impedance of the antenna 12 are not transmitted to the PA 86 and PA 96.

  FIG. 3 is an illustrative view showing a configuration of the antenna connection circuit 42. The antenna connection circuit 42 includes a capacitor C1, a capacitor C2, a capacitor C3, a coil L1, a coil L2, a coil L3, and a coil L4. Between the antenna 12 and the triplexer 44, these elements are connected in series in the order of the capacitor C1, the capacitor C2, the coil L3, and the coil L4 from the antenna 12 side. The capacitor C1 is connected to the antenna 12 and the coil L4 is connected to the triplexer 44.

  Further, one end of the coil L1 is connected between the capacitor C1 and the capacitor C2, and the other end of the coil L1 is grounded. Furthermore, one end of the coil L2 is connected between the capacitor C2 and the coil L3, and the other end of the coil L2 is grounded. Then, one end of a capacitor C3 is connected between the coil L3 and the coil L4, and the other end of the capacitor C3 is grounded.

  FIG. 4 is a Smith chart obtained by measuring between the antenna 12 and the antenna connection circuit 42 and between the triplexer 44 and the duplexer 54 for 2 GHz band. Referring to FIG. 4, this Smith chart represents an impedance that changes in response to a change in frequency in a state where the measurement resistance is 50Ω. Point T1 indicates the impedance when the frequency is 2.0 GHz (predetermined frequency), and point T2 indicates the impedance when the frequency is 5.83 GHz (harmonic of the predetermined frequency or a frequency in the vicinity thereof).

  The point T1 is located near the center of the Smith chart, and the impedance is close to 50Ω. Therefore, it can be seen that the frequency band of the telephone signal including 2.0 GHz is matched between the antenna 12 and the triplexer 44. Further, the point T2 is located on the short-circuit side, and the impedance is smaller than 50Ω. Therefore, it can be seen that the ETC signal band including 5.83 GHz (as an example, 5770 to 5890 MHz) is set to be mismatched between the antenna 12 and the triplexer 44. Therefore, the spurious to the ETC signal band can be effectively suppressed by the antenna connection circuit 42.

  Here, in the communication module 10 of the in-vehicle device 100, a standard for spurious to the ETC signal band (second frequency band) corresponding to the third harmonic of the 2 GHz band (2000 MHz band) which is the first frequency band is determined by the communication carrier. It has been. For this reason, conventionally, by selecting a part or inserting a filter between the isolator 88 and the duplexer 54, spurious to the ETC signal band has been supported.

  However, in the conventional communication module, the spurious generated from the PA 86 to the ETC signal band may be reflected by the shield plate provided in the communication module and input directly to the triplexer 44. If spurious signals to the ETC signal band are directly input to the triplexer 44, spurious signals to the ETC signal band are radiated from the antenna 12.

  Therefore, in this embodiment, by providing the antenna connection circuit 42 that makes the spurious to the ETC signal band mismatch between the triplexer 44 and the antenna 12, the spurious to the ETC signal band radiated from the antenna 12 is provided. Suppress. As a result, in this embodiment, by providing the antenna connection circuit 42, it is possible to suppress the spurious to the ETC signal band radiated from the antenna 12 by about 2.5 to 3.0 dB.

  In addition, since the in-vehicle device 100 includes the communication module 10 according to the present embodiment, the countermeasure against spurious to the ETC signal band is more effectively exhibited.

  Even if the antenna connection circuit 42 is added, the telephone signal in the 800 MHz band is not affected, so that it is not necessary to turn on / off the antenna connection circuit 42 according to the signal received / transmitted.

  Further, the present embodiment is not limited to the in-vehicle device 100 but may be applied to a mobile phone, a so-called smart phone, and a PDA (Personal Digital Assistant). Also, the in-vehicle device 100 may be other appropriate devices other than the navigation system.

  In addition, the specific numerical values such as the resistance value and impedance of the measurement resistor given in this specification are merely examples, and can be appropriately changed according to the necessity of product specifications and the like.

  The antenna connection circuit 42 according to the embodiment described above may have another circuit configuration as long as the spurious to the ETC signal band is suppressed.

DESCRIPTION OF SYMBOLS 10 ... Communication module 12 ... Antenna 16 ... Wireless communication circuit 18 ... Processor 40 ... RF circuit 42 ... Antenna connection circuit 44 ... Triplexer 86, 96 ... PA
100 ... On-vehicle equipment 200 ... Mobile phone base station

Claims (6)

In a communication module comprising: a duplexer that outputs a signal amplified by an amplifier; and an antenna that transmits a signal output from the duplexer.
An antenna connection circuit is provided between the antenna and the duplexer,
In the antenna connection circuit, matching is performed in a frequency band including a predetermined frequency used for communication with a base station, and mismatching occurs in a frequency band of an ETC signal including a harmonic of the predetermined frequency or a nearby 5.8 GHz. A communication module, characterized by being set as follows.   The communication module according to claim 1, wherein the frequency band including the predetermined frequency is a 2 GHz band.   An in-vehicle device comprising the communication module according to claim 1 or 2. A duplexer that outputs the signal amplified by the amplifier,
An antenna that transmits a signal output from the duplexer, and is provided between the antenna and the duplexer, and is matched in a frequency band that includes a predetermined frequency used for communication with a base station, and the predetermined A portable communication terminal comprising an antenna connection circuit set so as to be mismatched in a frequency band of an ETC signal including a harmonic of a frequency or a nearby 5.8 GHz. The mobile communication terminal according to claim 4, further comprising: a display unit; and a display control unit that displays a map image on the display unit.   The mobile communication terminal according to claim 4 or 5, wherein the frequency band including the predetermined frequency is a 2 GHz band.

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