JP6920605B2 - Communication device - Google Patents

Description

The present invention relates to a communication device that receives signals of different frequency bands.

In a communication device that can transmit and receive in multiple frequency bands for voice communication and receive GPS according to the geographical area, in order to reduce the size of the communication device, signals in multiple frequency bands with one antenna It is necessary to send and receive GPS signals. The communication device is provided according to each of a plurality of frequency bands, and includes a demultiplexing circuit through which signals included in the frequency band are passed.

The composite demultiplexing circuit disclosed in Patent Document 1 includes the Cellular frequency band of 800 MHz, the GPS (Global Positioning System) frequency band of 1500 MHz, and the PCS (Personal Communication Service). Demultiplexes the 1900 MHz band, which is a frequency band. The composite demultiplexing circuit is an LPF (Low-Pass Filter) provided between the antenna and the Cellular transmission / reception system as a demultiplexing circuit, and a phase adjustment provided between the antenna and the GPS receiving system. It is provided with a circuit for use and an HPF (High-Pass Filter) provided between the antenna and the PCS transmission / reception system. The phase adjustment circuit prevents interference between demultiplexing circuits by rotating the phase to increase the impedance of the phase adjustment circuit in a frequency band other than the GPS frequency band.

Japanese Unexamined Patent Publication No. 2005-1847773

The composite demultiplexing circuit disclosed in Patent Document 1 is connected to each of a Cellular transmission / reception system, a GPS reception system, and a PCS transmission / reception system, which are independent of each other. In a communication device capable of transmitting and receiving in a plurality of frequency bands for voice communication, it may be necessary to perform transmission and reception in a plurality of frequency bands by a common communication circuit. In this case, in the composite demultiplexing circuit disclosed in Patent Document 1, interference between the demultiplexing circuits may occur. In particular, for example, in a communication device capable of receiving LTE (Long Term Evolution) communication band 19 (800 MHz band), band 3 (1800 MHz band) and GPS signals, the distance between the GPS frequency band and band 3 is described in Patent Documents. Since it is narrower than the distance between the GPS frequency band and the PCS frequency band in 1, interference between demultiplexing circuits may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the accuracy of demultiplexing in a communication device that transmits and receives in a plurality of frequency bands.

In order to achieve the above object, the communication device according to the first aspect of the present invention is
With the antenna
A first communication unit that transmits and receives a signal included in the first frequency band and a signal included in a second frequency band lower than the first frequency band.
A second communication unit that receives at least a signal included in the third frequency band, which is lower than the first frequency band and higher than the second frequency band, and
A first demultiplexing circuit provided between the antenna and the first communication unit and passing a signal included in the first frequency band,
A second demultiplexing circuit provided in parallel with the first demultiplexing circuit between the antenna and the first communication unit and passing a signal included in the second frequency band, and a second demultiplexing circuit.
A third demultiplexing circuit provided between the antenna and the second communication unit and passing a signal included in the third frequency band,
Equipped with a,
The signal line having one end connected to the first communication unit is branched at the other end and connected to each of the first demultiplexing circuit and the second demultiplexing circuit.
The first demultiplexing circuit includes three capacitors connected in series, two capacitors having one end connected to each of the adjacent capacitors among the three capacitors, and each of the two capacitors. Has two inductors, one end connected in series and the other end grounded.
The second demultiplexing circuit comprises two inductors connected in series, two capacitors connected in parallel to each of the two inductors, and between both ends of the two inductors and the two inductors. and three capacitors having one end connected to the other end is grounded, respectively, that have a.

Preferably, before Symbol third diplexer circuit comprises a series resonance circuit having an inductor and a capacitor are connected in series.

Preferably, the difference obtained by subtracting the resonance frequency of the series resonance circuit from the self-resonance frequency of the inductor of the series resonance circuit is equal to or greater than the first threshold value, and the Q value indicating the sharpness of the series resonance circuit is the first. der two or more of the threshold is,
The first threshold is 500 MHz.
The second threshold, the first frequency band, the second frequency band, and Ru target der sharpness of claim 3, wherein said series resonant circuit according to the frequency band of.

Preferably, at least one of the distance between the first frequency band and the third frequency band and the distance between the second frequency band and the third frequency band is narrower than 200 MHz.

Preferably, the communicator performs LTE (Long Term Evolution) communication and performs LTE (Long Term Evolution) communication.
The first frequency band includes the 1800 MHz band and the 2100 MHz band in the LTE communication.
The second frequency band includes the 800 MHz band in the LTE communication, and includes the 800 MHz band.
The third frequency band is a frequency band including 1575.42 MHz assigned to GPS (Global Positioning System).

According to the present invention, a first demultiplexing circuit provided between the antenna and the first communication unit and passing a signal included in the first frequency band, and between the antenna and the first communication unit. A second demultiplexing circuit provided in parallel with the first demultiplexing circuit and passing signals included in the second frequency band, and a third frequency provided between the antenna and the second communication unit. It is possible to improve the accuracy of demultiplexing by the third demultiplexing circuit that passes the signal included in the band.

A block diagram showing a configuration example of a communication device according to an embodiment of the present invention. A block diagram showing another configuration example of the communication device according to the embodiment. Diagram showing a configuration example of the Wilkinson divider Diagram showing the damping characteristics of the Wilkinson divider Smith chart showing the impedance curve of the Wilkinson divider The figure which shows the configuration example of 2 signal pads 2 The figure which shows the attenuation characteristic of a signal pad Smith chart showing impedance curve of 2 signal pads Diagram showing a configuration example of a branch circuit The figure which shows the attenuation characteristic of a branch circuit Smith chart showing the impedance curve of a branch circuit The figure which shows the example of the demultiplexing circuit which the communication device which concerns on embodiment has. The figure which shows the attenuation characteristic of the demultiplexing circuit of the communication device which concerns on embodiment. Smith chart showing the impedance curve of the demultiplexing circuit according to the embodiment The figure which shows another example of the 1st demultiplexing circuit of the communication apparatus which concerns on embodiment. The figure which shows another example of the 2nd demultiplexing circuit of the communication device which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the figure, the same or equivalent parts are designated by the same reference numerals.

FIG. 1 is a block diagram showing a configuration example of a communication device according to an embodiment of the present invention. The communication device 1 includes an antenna 11, a first demultiplexing circuit 12 for passing a signal included in the first frequency band, a second demultiplexing circuit 13 for passing a signal included in the second frequency band, and a second demultiplexing circuit 13. A third demultiplexing circuit 14 for passing a signal included in the frequency band 3 is provided. The second frequency band is lower than the first frequency band. The third frequency band is lower than the first frequency band and higher than the second frequency band. The communication device 1 receives at least the signal included in the first frequency band, the first communication unit 15 for transmitting and receiving the signal included in the second frequency band, and the signal included in the third frequency band. The communication unit 16 of the above is further provided.

The first demultiplexing circuit 12 is provided between the antenna 11 and the first communication unit 15. The second demultiplexing circuit 13 is provided between the antenna 11 and the first communication unit 15 in parallel with the first demultiplexing circuit 12. The third demultiplexing circuit 14 is provided between the antenna 11 and the second communication unit 16. The signal line having one end connected to the antenna 11 is branched at the other end and connected to each of the first demultiplexing circuit 12, the second demultiplexing circuit 13, and the third demultiplexing circuit 14. Further, the signal line having one end connected to the first communication unit 15 is branched at the other end and connected to each of the first demultiplexing circuit 12 and the second demultiplexing circuit 13.

The first demultiplexing circuit 12 passes a signal included in the first frequency band among the signals input from the side of the antenna 11 and the side of the first communication unit 15. The second demultiplexing circuit 13 passes a signal included in the second frequency band among the signals input from the side of the antenna 11 and the side of the first communication unit 15. The third demultiplexing circuit 14 passes a signal included in the third frequency band among the signals input from the antenna 11 side. By providing the first demultiplexing circuit 12, the second demultiplexing circuit 13, and the third demultiplexing circuit 14, each of the first frequency band, the second frequency band, and the third frequency band is provided. The signal can be demultiplexed.

Each part of the communication device 1 is controlled by the controller 20. The controller 20 includes a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 23, and a ROM (Read-Only Memory) 24. The signal lines from the controller 20 to each part are omitted in order to avoid complication and facilitate understanding. The controller 20 is connected to each part of the communication device 1 via I / O (Input / Output) 22, and controls the start, end, and processing contents of those processes. The ROM 24 stores a control program for the controller 20 to control the operation of the communication device 1. The controller 20 controls the communication device 1 based on the control program.

The operation of the communication device 1 at the time of receiving a signal will be described. When the received signal received by the antenna 11 is included in the first frequency band, the received signal passes through the first demultiplexing circuit 12 and is sent to the first communication unit 15. When the received signal is included in the second frequency band, the received signal passes through the second demultiplexing circuit 13 and is sent to the first communication unit 15. When the received signal is included in the third frequency band, the received signal passes through the third demultiplexing circuit 14 and is transmitted to the second communication unit 16. The first communication unit 15 performs demodulation processing of the transmitted received signal and outputs the demodulated signal. When the received signal is included in the third frequency band, the received signal passes through the third demultiplexing circuit 14 and is transmitted to the second communication unit 16. The second communication unit 16 performs demodulation processing of the transmitted received signal and outputs the demodulated signal. The communication device 1 includes a first demultiplexing circuit 12, a second demultiplexing circuit 13, and a third demultiplexing circuit 14, so that the first frequency can be obtained without causing interference between the demultiplexing circuits. It is possible to receive signals contained in any of the bands, the second frequency band, and the third frequency band.

The operation of the communication device 1 at the time of signal transmission will be described. The first communication unit 15 generates a transmission signal based on the input audio signal, for example, and transmits the transmission signal. When the transmission signal is included in the first frequency band, the transmission signal passes through the first demultiplexing circuit 12 and is sent to the antenna 11. When the transmission signal is included in the second frequency band, the transmission signal passes through the second demultiplexing circuit 13 and is sent to the antenna 11. The antenna 11 transmits the transmitted transmission signal. The communication device 1 includes a first demultiplexing circuit 12, a second demultiplexing circuit 13, and a third demultiplexing circuit 14, so that the first frequency can be obtained without causing interference between the demultiplexing circuits. It is possible to transmit signals contained in either the band or the second frequency band.

At least one of the interval between the first frequency band and the third frequency band and the interval between the second frequency band and the third frequency band may be narrower than the defined interval. For example, the distance between the first frequency band and the third frequency band is narrower than 200 MHz. The communication device 1 transmits, for example, LTE (Long Term Evolution) communication band 19 (800 MHz band), band 3 (1800 MHz band), band 1 (2100 MHz band), and GPS (Global Positioning System) signals. It is a receivable communication device. In this case, the first frequency band includes the 1800 MHz band and the 2100 MHz band, the second frequency band includes the 800 MHz band, and the third frequency band includes the 1575.42 MHz assigned to GPS.

FIG. 2 is a block diagram showing another configuration example of the communication device according to the embodiment. As shown in FIG. 2, when the second communication unit 16 is a GPS receiving unit, the communication device 1 has a SAW (Surface Acoustic Wave) filter in addition to the configuration of the communication device 1 shown in FIG. 17, 18 and LNA (Low Noise Amplifier) 19 may be provided. The SAW filter 17 has a sufficiently low insertion loss. The SAW filter 18 is a band pass filter having a sufficiently narrow frequency band including a frequency assigned to GPS as a pass band.

Wilkinson dividers and two-signal pads are known as means for branching one signal into two signals and merging the two signals into one signal. FIG. 3 is a diagram showing a configuration example of a Wilkinson divider. The Wilkinson divider 30 branches the signal input from the terminal 31 into two signals and outputs the signal from each of the terminals 32 and 33. Further, the Wilkinson divider 30 merges the signals input from the terminals 32 and 33 and outputs the signals from the terminals 31. The Wilkinson divider 30 has a resistor 34 provided between terminals 31 and 32, a resistor 35 provided between terminals 31 and 33, and one end connected between the resistor 34 and the terminal 32 and the other end of the resistor 35. A resistor 36 connected between the terminal 33 and the terminal 33 is provided.

An example will be described in which a pseudo load of 50Ω is connected to each of the terminals 31, 32 and 33, the resistance value of each of the resistors 34 and 35 is 68Ω, and the resistance value of the resistor 36 is 100Ω. FIG. 4 is a diagram showing the damping characteristics of the Wilkinson divider. In FIG. 4, the horizontal axis is the frequency (unit: GHz), and the vertical axis is the amount of attenuation (unit: dB). In FIG. 4, m1 indicates the amount of attenuation assigned to GPS at 1.575 GHz, m2 indicates the amount of attenuation at 1.7 GHz included in the 1800 MHz band, and m3 indicates the amount of attenuation at 800 MHz included in the 800 MHz band. From FIG. 4, it can be seen that the amount of attenuation is approximately 6 dB when demultiplexed by the Wilkinson divider 30.

FIG. 5 is a Smith chart showing the impedance curve of the Wilkinson divider. The thick solid line in FIG. 5 shows the impedance seen from the terminal 31 from 0 Hz to 5 GHz. The thin solid line in FIG. 5 shows the impedance seen from the terminal 32 from 0 Hz to 5 GHz. The impedance seen from the terminal 31 and the impedance seen from the terminal 32 are matched in the vicinity of 50Ω.

FIG. 6 is a diagram showing a configuration example of a two-signal pad. The two signal pad 40 branches the signal input from the terminal 41 into two signals and outputs the signal from each of the terminals 42 and 43. Further, the 2 signal pad 41 merges the signals input from the terminals 42 and 43, and outputs the signals from the terminals 41. The two signal pads 40 are provided between terminals 41 and 42, resistors 44 and 45 connected in series, and a resistor 46 having one end connected between the resistors 44 and 45 and the other end connected to the terminal 43. To be equipped.

A case where a 50Ω pseudo load is connected to each of the terminals 41, 42, and 43 and the resistance value of each of the resistors 44, 45, and 46 is set to 15Ω will be described as an example. FIG. 7 is a diagram showing the attenuation characteristics of the two signal pads. The way of reading the figure is the same as that of FIG. In FIG. 7, m1 indicates the amount of attenuation assigned to GPS at 1.575 GHz, m2 indicates the amount of attenuation at 1.7 GHz included in the 1800 MHz band, and m4 indicates the amount of attenuation at 881 MHz included in the 800 MHz band. From FIG. 7, it can be seen that, similarly to the Wilkinson divider 30, the amount of attenuation is approximately 6 dB when the signal is demultiplexed by the two-signal pad 40.

FIG. 8 is a Smith chart showing the impedance curve of the two signal pads. The thick solid line in FIG. 8 shows the impedance seen from the terminal 41 from 0 Hz to 5 GHz. The thin solid line in FIG. 8 shows the impedance seen from the terminal 42 from 0 Hz to 5 GHz. In FIG. 8, the thick solid line and the thin solid line overlap. The impedance seen from the terminal 41 and the impedance seen from the terminal 42 are matched to approximately 50Ω.

FIG. 9 is a diagram showing a configuration example of a branch circuit. The branch circuit 50 is a circuit in which a signal line is simply branched without providing a resistor like the Wilkinson divider 30 and the two signal pad 40. A case where a 50Ω pseudo load is connected to each of the terminals 51, 52, and 53 will be described as an example. FIG. 10 is a diagram showing the attenuation characteristics of the branch circuit. The way of reading the figure is the same as that of FIG. In FIG. 10, m1 indicates the amount of attenuation assigned to GPS at 1.575 GHz, m2 indicates the amount of attenuation at 1.7 GHz included in the 1800 MHz band, and m4 indicates the amount of attenuation at 881 MHz included in the 800 MHz band. From FIG. 10, it can be seen that the amount of attenuation is approximately 3.5 dB when the branch circuit 50 demultiplexes.

FIG. 11 is a Smith chart showing the impedance curve of the branch circuit. Black circles in FIG. 11 indicate impedances seen from terminals 51 and 52 from 0 Hz to 5 GHz. It can be seen that the impedance seen from the terminal 51 and the impedance seen from the terminal 52 are not matched.

When the Wilkinson divider 30, the two signal pads 40, and the branch circuit 50 are used in the communication device 1 that transmits and receives signals in a plurality of frequency bands, demultiplexing cannot be sufficiently performed, and the power of the desired signal is attenuated. In particular, in the communication device 1 having the LNA 19 as shown in FIG. 2, when the power of the received signal is attenuated between the antenna 11 and the LNA 19, the S / N (Signal-to-Noise) ratio of the received signal becomes high. descend. Even if an amplifier is provided after the LNA 19, both the signal and noise are amplified by the amplifier, so that the lowered S / N ratio cannot be improved.

FIG. 12 is a diagram showing an example of a demultiplexing circuit included in the communication device according to the embodiment. In the embodiment, the first demultiplexing circuit 12 includes a T-type HPF (High-Pass Filter) having a plurality of capacitors connected in series. In the example of FIG. 12, the first demultiplexing circuit 12 includes capacitors 121 and 122 connected in series, and an inductor 123 having one end connected between the capacitors 121 and 122 and the other end grounded. In the embodiment, the second demultiplexing circuit 13 includes a T-type LPF (Low-Pass Filter) having a plurality of inductors connected in series. In the example of FIG. 12, the second demultiplexing circuit 13 includes inductors 131 and 132 connected in series, and a capacitor 133 having one end connected between the inductors 131 and 132 and the other end grounded.

In an embodiment, the third demultiplexing circuit 14 comprises a series resonant circuit having an inductor and a capacitor connected in series. In the example of FIG. 12, the third demultiplexing circuit 14 includes an inductor 141 and a capacitor 142 connected in series. The capacitor 142 may be realized by providing a gap in the transmission line. Further, the capacitor 142 may be composed of a plurality of capacitors connected in series. The difference obtained by subtracting the resonance frequency of the series resonance circuit from the self-resonance frequency of the inductor 141 of the series resonance circuit is equal to or larger than the first threshold value. The first threshold value is, for example, 500 MHz, and the self-resonant frequency of the inductor 141 is 500 MHz higher than the resonance frequency of the series resonance circuit. The Q value indicating the sharpness of the series resonant circuit is equal to or higher than the second threshold value. The second threshold value is determined based on the sharpness required for the series resonant circuit according to the frequency band transmitted and received by the communication device 1. By increasing the inductance of the inductor 141 as much as possible within the range where the difference obtained by subtracting the resonance frequency of the series resonance circuit from the self-resonance frequency of the inductor 141 of the series resonance circuit becomes equal to or more than the first threshold value, sufficiently sharp series resonance is performed. You can get the circuit.

FIG. 13 is a diagram showing the attenuation characteristics of the demultiplexing circuit of the communication device according to the embodiment. The way of reading the figure is the same as that of FIG. In FIG. 13, the thick solid line shows the attenuation characteristics of the demultiplexing circuit composed of the first demultiplexing circuit 12 and the second demultiplexing circuit 13. In FIG. 13, the thin solid line shows the attenuation characteristic of the third demultiplexing circuit 14. In FIG. 13, m1 shows the amount of attenuation in the third demultiplexing circuit 14 at 1.575 GHz assigned to GPS, and m2 shows the amount of attenuation in the third demultiplexer circuit 14 at 1.7 GHz included in the 1800 MHz band. Indicates the amount of attenuation in the third demultiplexing circuit 14 at 800 MHz in which m3 is included in the 800 MHz band. The attenuation in the third demultiplexing circuit 14 at 1.575 GHz is 3.6 dB, while the attenuation in the third demultiplexer circuit 14 at 1.7 GHz and 800 MHz is 28.8 dB, 10 respectively. It is .1 dB.

When the received signal received by the antenna 11 is included in any of the 1800 MHz band, the 2100 MHz band and the 800 MHz band, the received signal is sufficiently attenuated by the third demultiplexing circuit 14. Further, since the transmission signal transmitted by the first communication unit 15 is a signal included in any of the 1800 MHz band, the 2100 MHz band, and the 800 MHz band, the transmission signal is sufficiently attenuated by the third demultiplexing circuit 14. On the other hand, when the received signal received by the antenna 11 is a GPS signal, the received signal passes through the third demultiplexing circuit 14 and is input to the second communication unit 16. It can be seen that by providing the third demultiplexing circuit 14, the frequencies of the 1800 MHz band, the 2100 MHz band and the 800 MHz band are sufficiently attenuated, and the GPS signal and other audio signals can be demultiplexed. The amount of attenuation in the third demultiplexing circuit 14 at 1.575 GHz is 3.6 dB, which is an acceptable range for the quality of GPS signals. By providing the third demultiplexing circuit 14, the inflow of transmission signals in the 1800 MHz band, 2100 MHz band, and 800 MHz band causes an abnormality in the second communication unit 16, SAW filters 17, 18, or LNA 19. It is possible to prevent it.

The attenuation characteristic shown by the thick solid line in FIG. 13 is a combination of the attenuation characteristic of the HPF included in the first demultiplexing circuit 12 and the attenuation characteristic of the LPF included in the second demultiplexing circuit 13. The cutoff frequencies of the HPF included in the first demultiplexing circuit 12 and the LPF included in the second demultiplexing circuit 13 are located in the vicinity of 1.5 GHz. The impedance of the first demultiplexing circuit 12 in the 800 MHz band is sufficiently large, and the impedance of the second demultiplexing circuit 13 in the 1800 MHz band and the 2100 MHz band is sufficiently large. Therefore, interference does not occur between the first demultiplexing circuit 12 and the second demultiplexing circuit 13. The received signal received by the antenna 11 passes through either the first demultiplexing circuit 12 or the second demultiplexing circuit 13 and is input to the first communication unit 15. The transmission signal transmitted from the first communication unit 15 passes through either the first demultiplexing circuit 12 or the second demultiplexing circuit 13 and is sent to the antenna 11.

In FIG. 13, the amount of attenuation in the demultiplexing circuit composed of the first demultiplexing circuit 12 and the second demultiplexing circuit 13 at 1.575 GHz assigned to GPS is shown, and m6 is included in the 1800 MHz band. The amount of attenuation in the demultiplexing circuit composed of the first demultiplexing circuit 12 and the second demultiplexing circuit 13 at 1.7 GHz is shown, and the first demultiplexing at 800 MHz in which m7 is included in the 800 MHz band. The amount of attenuation in the demultiplexing circuit composed of the circuit 12 and the second demultiplexing circuit 13 is shown. The attenuation in the demultiplexing circuit composed of the first demultiplexing circuit 12 and the second demultiplexing circuit 13 at 1.575 GHz is about 10 dB, whereas the attenuation at 1.7 GHz and 800 MHz is the first. The attenuation in the demultiplexing circuit including the demultiplexing circuit 12 and the second demultiplexing circuit 13 is 1.5 dB and 0.3 dB. By providing the first demultiplexing circuit 12 and the second demultiplexing circuit 13, the frequency in the vicinity of the frequency assigned to the GPS is sufficiently attenuated, and the GPS signal and other audio signals can be demultiplexed. It turns out that it is possible. Further, it can be seen that the attenuations at 1.7 GHz and 800 MHz are as small as 1.5 dB and 0.3 dB, and that the communication quality is not significantly deteriorated due to demultiplexing.

When the received signal received by the antenna 11 is a GPS signal, the received signal is sufficiently attenuated by the first demultiplexing circuit 12 and the second demultiplexing circuit 13. On the other hand, when the received signal sent from the antenna 11 is included in either the 1800 MHz band or the 2100 MHz band, the received signal is sufficiently attenuated by the first demultiplexing circuit 12 but passes through the second demultiplexing circuit 13. do. When the received signal transmitted from the antenna 11 is included in the 800 MHz band, the received signal passes through the first demultiplexing circuit 12, but is sufficiently attenuated in the second demultiplexing circuit 13. By providing the first demultiplexing circuit 12 and the second demultiplexing circuit 13, the frequency of the GPS signal is sufficiently attenuated, and it is possible to demultiplex the GPS signal and other audio signals. Recognize.

FIG. 14 is a Smith chart showing the impedance curve of the demultiplexing circuit according to the embodiment. The thick solid line in FIG. 14 shows the impedance seen from the antenna 11 from 0 Hz to 5 GHz. The thin solid line in FIG. 14 shows the impedance seen from the first communication unit 15 from 0 Hz to 5 GHz. In FIG. 14, m8 shows the impedance seen from the antenna 11 at 1.575 GHz, m9 shows the impedance seen from the antenna 11 at 1.7 GHz, and m10 shows the impedance seen from the antenna 11 at 900 MHz. The VSWR (Voltage Standing Wave Ratio) at the terminal of the antenna 11 at 1.7 GHz is 1.7, and the VSWR at the terminal of the antenna 11 at 900 MHz is 1.3. In FIG. 14, m11 shows the impedance seen from the first communication unit 15 at 1.7 GHz, and m12 shows the impedance seen from the first communication unit 15 at 800 MHz. From FIG. 14, it can be seen that impedance matching is achieved at 800 MHz and 900 MHz.

As described above, according to the communication device 1 according to the present embodiment, the first portion provided between the antenna 11 and the first communication unit 15 and passing a signal included in the first frequency band is provided. A second demultiplexing circuit 13, which is provided in parallel with the first demultiplexing circuit 12 between the wave circuit 12, the antenna 11 and the first communication unit 15, and allows signals included in the second frequency band to pass through. The accuracy of demultiplexing can be improved by a third demultiplexing circuit 14 provided between the antenna 11 and the second communication unit 16 and passing a signal included in the third frequency band. ..

The embodiment of the present invention is not limited to the above-described embodiment. The circuit configuration in the above-described embodiment is an example. FIG. 15 is a diagram showing another example of the first demultiplexing circuit of the communication device according to the embodiment. The first demultiplexing circuit 12 shown in FIG. 15 includes capacitors 121, 124, 122 connected in series, capacitors 125 and inductor 123 connected in series, and capacitors 126 and inductor 127 connected in series. .. One end of the capacitor 125 is connected between the capacitors 121 and 124, and one end of the inductor 123 is grounded. One end of the capacitor 126 is connected between the capacitors 124 and 122, and one end of the inductor 127 is grounded. FIG. 16 is a diagram showing another example of the second demultiplexing circuit of the communication device according to the embodiment. The second demultiplexing circuit 13 shown in FIG. 16 is a simultaneous Chebyshev type fifth-order LPF. The second demultiplexing circuit 13 shown in FIG. 16 includes capacitors 134 and 135 connected in parallel with the inductors 131 and 132, respectively, in addition to the configuration of the second demultiplexing circuit 13 shown in FIG. The second demultiplexing circuit 13 shown in FIG. 16 further includes a capacitor 136 in which one end is connected to each of one end of the inductor 131 and one end of the capacitor 134 and the other end is grounded, and one end of the inductor 132 and one end of the capacitor 135. A capacitor 137 is provided, one end of which is connected to each of the above and the other end of which is grounded. In the second demultiplexing circuit 13 shown in FIG. 16, one end of the capacitor 133 is connected to the connection points of the inductors 131 and 132 and the connection points of the capacitors 134 and 135, respectively.

The frequency band transmitted and received by the communication device 1 is not limited to the above example. Further, the second communication unit 16 is not limited to the GPS receiving unit, and may transmit and receive signals included in the third frequency band.

1 Communication device
11 antenna
12 First demultiplexing circuit
13 Second demultiplexing circuit
14 Third demultiplexing circuit
15 First communication unit
16 Second communication unit
17,18 SAW filter
19 LNA
20 controller
21 CPU
22 I / O
23 RAM
24 ROM
30 Wilkinson Divider
31, 32, 33, 41, 42,
43, 51, 52, 53 terminals 34, 35, 36, 44, 45, 46 resistors
40 2 signal pad
50 branch circuit 121, 122, 124, 125,
126,133,134,135,
136, 137, 142 Capacitors 123, 127, 131, 132, 141 Inductors

Claims (5)

With the antenna
A first communication unit that transmits and receives a signal included in the first frequency band and a signal included in a second frequency band lower than the first frequency band, and
A second communication unit that receives at least a signal included in the third frequency band, which is lower than the first frequency band and higher than the second frequency band, and
A first demultiplexing circuit provided between the antenna and the first communication unit and passing a signal included in the first frequency band,
A second demultiplexing circuit provided in parallel with the first demultiplexing circuit between the antenna and the first communication unit and passing a signal included in the second frequency band, and a second demultiplexing circuit.
A third demultiplexing circuit provided between the antenna and the second communication unit and passing a signal included in the third frequency band,
Equipped with a,
The signal line having one end connected to the first communication unit is branched at the other end and connected to each of the first demultiplexing circuit and the second demultiplexing circuit.
The first demultiplexing circuit includes three capacitors connected in series, two capacitors having one end connected to each of the adjacent capacitors among the three capacitors, and each of the two capacitors. Has two inductors, one end connected in series and the other end grounded.
The second demultiplexing circuit comprises two inductors connected in series, two capacitors connected in parallel to each of the two inductors, and between both ends of the two inductors and the two inductors. Each has three capacitors, one end connected and the other end grounded.
Communication machine. Before Symbol third diplexer circuit comprises a series resonance circuit having an inductor and a capacitor connected in series,
The communication device according to claim 1. The difference obtained by subtracting the resonance frequency of the series resonance circuit from the self-resonance frequency of the inductor of the series resonance circuit is equal to or greater than the first threshold value, and the Q value indicating the sharpness of the series resonance circuit is the second threshold value. Ri der above,
The first threshold is 500 MHz.
The second threshold value is a target value of the sharpness of the series resonant circuit according to the first frequency band, the second frequency band, and the third frequency band.
Communication apparatus according to請Motomeko 2. Claims 1 to 3 in which at least one of the distance between the first frequency band and the third frequency band and the distance between the second frequency band and the third frequency band is narrower than 200 MHz. The communication device according to any one item. The communication device performs LTE (Long Term Evolution) communication and performs LTE (Long Term Evolution) communication.
The first frequency band includes the 1800 MHz band and the 2100 MHz band in the LTE communication.
The second frequency band includes the 800 MHz band in the LTE communication, and includes the 800 MHz band.
The third frequency band is a frequency band including 1575.42 MHz assigned to GPS (Global Positioning System).
The communication device according to claim 4.

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