wireless communication device

Abstract

To make it possible to switch between wired connection and wireless connection with a simple configuration while suppressing deterioration of wireless communication characteristics.SOLUTION: A wireless communication device includes a communication unit that performs via a microstrip line at least one of transmission of a signal to an antenna and reception of a signal from the antenna. A first stub on the communication unit side and a second stub on the antenna side, which have resonance characteristics, are formed in the microstrip line.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wireless communication device. [Background technology]

[0002] Some wireless communication devices are capable of switching between a wired connection for performing evaluation or wireless certification tests, and a wireless connection via an antenna, on a microstrip line connected from a wireless front-end circuit to an antenna. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-21925 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the need for a wired / wireless connection switchover can increase costs due to increased man-hours, and can also lead to problems such as degradation of the wireless communication characteristics of the wireless communication device. Furthermore, using an element such as an RF switch to switch between wired and wireless connections can lead to an increase in the number of components.

[0005] An aspect of the present disclosure is to enable switching between wired connection and wireless connection with a simple configuration while suppressing degradation of wireless communication characteristics. [Means for solving the problem]

[0006] One aspect of the present disclosure is exemplified by a wireless communication device. The wireless communication device includes a communication unit that transmits signals to an antenna and / or receives signals from the antenna via a microstrip line. The microstrip line is formed with a first stub on the communication unit side and a second stub on the antenna side, both of which have resonance characteristics. [Effects of the Invention]

[0007] According to this wireless communication device, it is possible to switch between wired connection and wireless connection with a simple configuration while suppressing degradation of wireless communication characteristics. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a wireless communication device according to a comparative example. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a wireless communication device according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating the configuration of a microstrip line and a bandpass filter. [Figure 4] FIG. 4 is a diagram illustrating a configuration of a wireless communication device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A wireless communication device according to an embodiment will be described below with reference to the drawings. <Comparative Example> 1 is a diagram illustrating a configuration of a wireless communication device 500 according to a comparative example. The wireless communication device 500 includes a wireless integrated circuit 1 (wireless IC 1) and a coaxial cable for connecting the wireless integrated circuit 1 and the coaxial cable. The wireless communication device includes a connector 3, an antenna 4, and a microstrip line 502 that connects the wireless IC 1 and the connector 3 or the wireless IC 1 and the antenna 4.

[0010] The microstrip line 502 is separated into a microstrip line 502-2 connected to the wireless IC 1, a microstrip line 502-3 connected to the connector 3, and a microstrip line 502-4 connected to the antenna 4.

[0011] As shown in FIG. 1, one end of the microstrip line 502-2 is connected to a transmitting / receiving port of the front-end circuit of the wireless IC 1. One end of the microstrip line 502-3 is connected to the connector 3. Furthermore, one end of the microstrip line 502-4 is connected to the antenna 4. Meanwhile, the other end of the microstrip line 502-2 opposite the wireless IC 1 side is connected to the microstrip line 502-3 or 502-4 by a short-circuit element or an RF switch. That is, the microstrip line 502-2 can be connected to either the other end of the microstrip line 502-3 opposite the connector 3 or the other end of the microstrip line 502-4 opposite the antenna 4. Furthermore, impedance matching between the connector 3 and the microstrip line 502-3 is ensured by a matching circuit (not shown in FIG. 1). Furthermore, impedance matching between the antenna 4 and the microstrip line 502-4 is ensured by a matching circuit (not shown in FIG. 1).

[0012] Here, in order to switch the connection between the microstrip line 502-2 and one of the microstrip lines 502-3 and 502-4, for example, a short-circuit element provided on the microstrip line is replaced by soldering, etc. Alternatively, the above switching can be performed by implementing an RF switch between the microstrip line 502-2 and the microstrip lines 502-3 and 502-4.

[0013] In this manner, the transmitting / receiving port of the wireless IC 1 is connected to the antenna 4 via the microstrip line 502-2 and the microstrip line 502-4 during wireless communication. On the other hand, during evaluation of the wireless communication device 500 or wireless certification testing, the transmitting / receiving port of the wireless IC 1 may be connected to the connector 3 of a coaxial cable of an external device such as a test device via the microstrip line 502-3. For this connection, the above-mentioned soldering or a means such as an RF switch is used.

[0014] However, if the replacement is performed by soldering a short-circuiting element, the increased man-hours required will increase costs. Furthermore, mounting an RF switch will increase the number of components. Furthermore, whether the short-circuiting element is soldered or an RF switch is mounted, it may be impossible to avoid affecting the transmission line characteristics between the microstrip line 502-2 and the microstrip lines 502-3 and 502-4. As a result, the wireless communication characteristics of the wireless communication device 500 may be degraded.

[0015] <Embodiment 1> 2 and 3, a wireless communication device 100 according to the first embodiment will be described. Fig. 2 is a diagram illustrating a configuration of the wireless communication device 100 according to the first embodiment. The wireless communication device 100 includes a wireless IC 1, a connector 3 for a coaxial cable connected to an external device such as a test device, an antenna 4, a microstrip line 2 connecting paths from the wireless IC 1 to the connector 3 and the antenna 4, and a bandpass filter BPF.

[0016] The wireless IC1 can be considered an example of a communication unit. Figure 2 illustrates the front-end circuit portion of the wireless IC1. This front-end circuit portion includes a modulation circuit portion and a demodulation circuit portion. The modulation circuit portion of the wireless IC1 has a mixer MX1 ​​that generates a high-frequency modulated signal from a signal from a phase-locked loop PLL and an input signal (baseband signal), and a power amplifier PA that amplifies the output signal from the mixer MX1. The output signal from the power amplifier PA is sent to the microstrip line 2 via a switch SW. The demodulation circuit portion of the wireless IC1 also demodulates the high-frequency signal input via the switch SW. It has a low-noise amplifier (LNA) that amplifies the received signal, and a mixer (MX2) that demodulates the amplified received signal into a baseband signal based on a phase-locked loop (PLL) signal. The phase-locked loop (PLL) and switch (SW) operate in both the modulation circuit section and the demodulation circuit section.

[0017] The microstrip line 2 branches off at a branch point to connect to a connector 3 of a coaxial cable, which is a connection cord, and to an antenna 4. The portion of the microstrip line 2 that connects from the branch point to the wireless IC 1 is called microstrip line 2-2. The portion of the microstrip line 2 that connects from the branch point to the connector 3 is called microstrip line 2-3. The portion of the microstrip line 2 that connects from the branch point to the antenna 4 is called microstrip line 2-4.

[0018] As shown in Figure 2, a bandpass filter BPF is inserted in the section of the microstrip line 2 from the branch to the connector 3 to the antenna 4. In other words, the bandpass filter BPF is inserted in the middle of the microstrip line 2-4.

[0019] When no coaxial cable is connected to the connector 3, the bandpass filter BPF has the characteristic of resonating at frequency f of the high frequency generated by the wireless IC 1. At this resonance, the bandpass filter BPF has a maximum admittance for signals of frequency f, and impedance matching is achieved between the antenna 4 and the microstrip line 2. Therefore, when no coaxial cable is connected to the connector 3, most of the power of the high-frequency signal of frequency f generated by the wireless IC 1 is radiated from the antenna 4 as a wireless signal.

[0020] On the other hand, when a coaxial cable is connected to the connector 3, the resonance characteristics of the bandpass filter BPF change due to the influence of the coaxial cable, causing impedance matching to be lost. In other words, the resonance characteristics are disrupted. As a result, the admittance of the bandpass filter BPF decreases with respect to the high frequency signal of frequency f generated by the wireless IC 1. Therefore, most of the power of the high frequency signal of frequency f generated by the wireless IC 1 is not transmitted to the antenna 4. In this way, when a coaxial cable is connected to the connector 3, the wireless communication device 100 can transmit most of the high frequency signal of frequency f generated by the wireless IC 1 to the coaxial cable. In other words, the wireless communication device 100 can switch the power of the high frequency signal of frequency f generated by the wireless IC 1 between the connector 3 and the antenna 4, depending on whether a coaxial cable is connected to the connector 3.

[0021] FIG. 3 illustrates the configuration of a microstrip line 2 and a bandpass filter BPF. As shown in FIG. 3, one end of the microstrip line 2-2 is connected to a wireless IC 1. Meanwhile, an open stub 5-3 serving as a first stub is formed at the other end of the microstrip line 2-2 opposite the wireless IC 1. Here, the open stub 5-3 can be considered as a wiring pattern on a dielectric substrate, with one end connected to the microstrip line 2-2 and the other end open. Note that a connector 3 for a coaxial cable is connected to the other end of the open stub 5-3. Furthermore, one end of the microstrip line 2-4 is connected to an antenna 4. Meanwhile, an open stub 5-4 serving as a second stub is formed at the other end of the microstrip line 2-4 opposite the antenna 4. Here, the open stub 5-4 can be considered as a wiring pattern on a dielectric substrate, with one end connected to the microstrip line 2-4 and the other end open. 3 illustrates the strip conductor of the microstrip line 2, but omits the dielectric substrate and the ground conductor on the back side of the dielectric substrate (the side opposite to the surface on which the microstrip line 2 is formed). Also, the microstrip lines 2-2, 2-4 and the open stubs 5-3, 5-4 are all formed as wiring patterns on the surface layer of the dielectric substrate, but some are formed on the inner layer of the dielectric substrate. In this case, the wiring patterns on the surface layer and the inner layer are connected by vias. As described above, an external device such as a test device can be connected to the coaxial cable. Therefore, it can be said that the first stub and the second stub have a characteristic that the resonance state is disrupted at the signal frequency when an external device is connected to the first stub.

[0022] In the example of FIG. 3 , the open stubs 5-3 and 5-4 are formed in parallel with a predetermined distance between them, and their mutual capacitance and mutual inductance form a kind of coupler. That is, the open stubs 5-3 and 5-4 are not electrically connected with respect to the DC component. By adjusting the length, width, thickness, and mutual distance of the open stubs 5-3 and 5-4, the admittance (and impedance) and frequency characteristics between the microstrip line 2-2 and the microstrip line 2-4 can be determined. In this embodiment, the open stubs 5-3 and 5-4 form a resonant circuit for a high-frequency signal of frequency f output from the wireless IC 1. Therefore, as illustrated in FIG. 3 , the open stubs 5-3 and 5-4 form a bandpass filter (BPF). This bandpass filter (BPF) has an admittance peak at frequency f.

[0023] <Effects of the embodiment> The wireless communication device 100 includes a wireless IC 1 as a communication unit that transmits signals to an antenna 4 and / or receives signals from the antenna 4 via a microstrip line 2. The microstrip line 2 is provided with an open stub 5-3, which is a first stub on the wireless IC 1 side and an open stub 5-4, which is a second stub on the antenna 4 side, both of which have resonance characteristics. The open stubs 5-3 and 5-4 can easily control the connection between the wireless IC 1 and the antenna 4 while suppressing fluctuations in the transmission line characteristics. For example, the connection between the wireless IC 1 and the antenna 4 can be controlled while suppressing an increase in the number of steps due to soldering a short-circuit element and an increase in the number of components due to mounting an RF switch, as in the comparative example of FIG. 1 .

[0024] In this way, the bandpass filter is configured simply by the open stubs 5-3 and 5-4. Furthermore, the open stub 5-3 is provided with a connector 3, which is a connection terminal for a coaxial cable. Therefore, the characteristics of the bandpass filter can be changed depending on whether or not a coaxial cable is connected. Therefore, without a coaxial cable connected, the open stubs 5-3 and 5-4 are resonated at the frequency f of the wireless signal to match the impedance between the antenna 4 and the microstrip line 2-4. More specifically, the dimensions of the open stubs 5-3 and 5-4, such as the length, width, thickness, and spacing of each part, can be adjusted. This allows the open stubs 5-3 and 5-4 to be configured so that the desired electromagnetic wave (high-frequency wave with frequency f) power is transmitted from the wireless IC 1 to the antenna 4. As a result, the signal from the wireless IC 1 is output to the antenna 4 via the open stubs 5-3 and 5-4. In this configuration, when a coaxial cable is connected to the connector 3, the open stubs 5-3 and 5-4 can be removed from the resonant state, and the supply of transmission / reception power (high-frequency power) from the wireless IC 1 to the antenna 4 can be reduced. In other words, when a coaxial cable is connected to the connector 3, the length of the open stub 5-3 increases by the length of the coaxial cable, which disrupts the resonance characteristics of the open stubs 5-3 and 5-4, and the supply of transmission / reception power (high-frequency power) from the wireless IC 1 to the antenna 4 can be reduced. On the other hand, at the above frequency f, it is possible to match the impedance between the open stub 5-3, the connector 3, the coaxial cable connected to the connector 3, and the devices, facilities, etc. connected to the coaxial cable. This impedance matching minimizes the reflection loss from the devices, facilities, etc. connected to the coaxial cable, for example, to -30 dB or less (the transmittance of high-frequency signals is almost Therefore, for example, the evaluation or radio recognition of the wireless communication device 100 can be suppressed. In a certification test or the like, the supply destination of the high-frequency power from the wireless IC 1 can be switched by a simple operation of connecting a test device to the coaxial cable, and the high-frequency power can be supplied to the test device via the open stub 5-3.

[0025] Furthermore, the open stubs 5-3 and 5-4 are not electrically connected with respect to DC components, so that DC signal components other than the high-frequency communication signal are not transmitted between the wireless IC 1 and the antenna 4, improving transmission quality.

[0026] <Embodiment 2> A wireless communication device 101 according to the second embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram illustrating an example of the configuration of the wireless communication device 101 according to the second embodiment. The wireless communication device 101 is obtained by adding a shield 7 to the wireless communication device 100 according to the first embodiment. Therefore, among the configurations of the wireless communication device 101, the configurations of the wireless IC 1, the microstrip line 2, the connector 3, the antenna 4, and the open stubs 5-3 and 5-4 are the same as those of the wireless communication device 100 according to the first embodiment.

[0027] 4 , in the wireless communication device 101, the wireless IC 1, the microstrip line 2, the coaxial cable connector 3, and the open stubs 5-3 and 5-4 are housed in a shield 7 formed of a radio wave shielding material. The shield 7 is also called a shield case. The shield 7 may also be called a radio wave absorber. The microstrip line 2, the coaxial cable connector 3, the open stubs 5-3 and 5-4 form a circuit portion including the microstrip line 2 extending from the wireless IC 1 serving as a communication unit to the antenna 4. In the second embodiment, the wireless IC 1 and this circuit portion are covered with the radio wave shielding material of the shield 7.

[0028] The shield 7 is, for example, a metal plate, a metal film, a metal mesh, or the like that surrounds the space. The radio wave absorber attenuates electromagnetic waves incident on the radio wave absorber through heat loss or resonance. The radio wave absorber is, for example, a dielectric material, a magnetic material such as ferrite, or the like. The shield 7 may be formed of a magnetic shielding material.

[0029] By storing wireless communication device 101 in the space inside shield 7, it is possible to suppress interference caused by high frequencies between the high-frequency circuit, including open stubs 5-3 and 5-4, which resonate in the frequency band being used, and the outside of shield 7. In addition, it is possible to suppress mutual interference waves between the high-frequency circuit and the outside of shield 7.

[0030] <Other variations> In the above-described first and second embodiments, the open stub 5-3 and the open stub 5-4 are used as the bandpass filter BPF. However, the configuration of the wireless communication devices 100 and 101 is not limited to the one using the open stub 5-3 and the open stub 5-4. It is sufficient for the wireless communication devices 100 and 101 to form a bandpass filter BPF that can suppress the radio signal power to the antenna 4 during evaluation, wireless certification testing, etc.

[0031] In order to form a bandpass filter BPF in the microstrip line 2, for example, a short stub may be used. For example, the end of the open stub 5-4 opposite to the end connected to the microstrip line 2-4 may be grounded. Also, a coupler provided at a distance from the microstrip lines 2-2 and 2-4 may be used. Also, what is called a branch line coupler branching from the microstrip lines 2-2 and 2-4 may be used. Also, what is called a Wilkinson coupler may be used, in which a resistor is provided in the microstrip lines 2-2 and 2-4 and connected to both ends of the resistor. Also, what is called a Wilkinson coupler, in which the microstrip lines 2-2 and 2-4 are each coupled by a row of divided conductors, may be used. A so-called parallel-coupled bandpass filter may also be used. By using such various high-frequency components, the degree of freedom in forming the bandpass filter BPF in the wireless communication devices 100 and 101 is improved, and an appropriate bandpass filter BPF can be configured. [Explanation of symbols]

[0032] 1 Wireless IC 2 Microstrip lines 3 Connectors 4 Antennas 5-3, 5-4 open stub 100 Wireless communication device

Claims

1. a communication unit that transmits a signal to an antenna and / or receives a signal from the antenna via a microstrip line; a first stub on the communication unit side and a second stub on the antenna side, both of which have resonance characteristics, are formed on the microstrip line; the first stub is configured to be connectable to an external device; The resonance characteristic is a characteristic in which a resonance state occurs at the frequency of the signal when the external device is not connected to the first stub, and the resonance state is disrupted at the frequency of the signal when the external device is connected to the first stub. Wireless communication device.

2. When the external device is not connected to the first stub, a signal from the communication unit is output to the antenna via the first stub and the second stub, The wireless communication device according to claim 1 , wherein when the external device is connected to the first stub, a signal from the communication unit is output to the external device via the first stub.

3. 2. The wireless communication device according to claim 1, wherein the first stub and the second stub have bandpass filter characteristics.

4. The wireless communication device according to claim 1 , wherein the first stub and the second stub are open stubs.

5. The wireless communication device according to claim 1 , wherein the first stub is provided with a connection terminal for connecting to the external device.

6. 6. The wireless communication device according to claim 5, wherein when a connection cord of the external device is connected to the connection terminal, the length of the first stub increases, causing the resonance characteristics to be disrupted.

7. The wireless communication device according to claim 1 , wherein the first stub and the second stub are not electrically connected with respect to a DC component.

8. The wireless communication device according to claim 1 , wherein a circuit portion including the communication unit and the microstrip line extending from the communication unit to the antenna is covered with a shielding material.

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