JP5088107B2 - Signal distribution device - Google Patents

Description

  The present invention relates to a signal distribution device that connects three or more signal transmission paths in common, and particularly when three or more communication devices are connected to each other in the same communication environment and the communication performance of the communication device is evaluated. The present invention relates to a signal distribution device suitable for application to the above.

  Conventionally, when evaluating and developing a wireless communication device (or software for the wireless communication device) that communicates wirelessly such as a mobile phone, stable communication without being affected by noise or reflected waves from the outside. In order to create a state that can be performed, wireless communication devices may be connected to each other by a wire such as a coaxial cable.

  In this case, if there are two wireless communication devices to be connected, the ports of the two wireless communication devices need only be directly connected with one cable, but when three or more wireless communication devices are connected. If the signal is not equally distributed among all the ports connected to the wireless communication device, the signal transmission / reception state corresponding to the wireless communication state in each wireless device cannot be accurately reproduced. However, in order to equalize the distribution among three or more ports, it is necessary to use a combination of signal distributors and attenuators, and it is necessary to construct a complex and large-scale network.

  Also, a distributor that distributes a signal input from one input port to a plurality of output ports has been proposed, but since the impedance is not constant among all the ports, three or more high-frequency transmission lines are connected. Not available for distributors.

Patent Document 1 discloses a power distributor that divides one signal into two in the microwave band and the millimeter wave band.
JP 2000-307313 A

  As described above, three or more wireless communication devices are directly connected by wire, and signals are transmitted and received between two wireless communication devices among the plurality of connected wireless communication devices, while other wireless communication devices are connected. There are cases where it is desired to measure the mutual influence between three or more wireless communication devices, such as measurement of the effect on the communication device. However, since the conventional distributor does not have the same impedance at all ports, it does not have a wired connection state that reproduces the wireless communication environment, and it is difficult to accurately measure the influence.

  In the case of a connection configuration using a conventional distributor, for example, when a low-loss microwave power distributor is used, there is a problem that the signal is distorted on the receiving side when the signal strength is strong.

  According to the present invention, a plurality of communication devices such as wireless communication devices can be connected to equalize the communication state of each communication device, and signals transmitted between the communication devices can be easily set as appropriate signals. An object is to provide a signal distribution device.

The present invention provides a signal distribution device that includes at least three input / output ports, and each input / output port has the same characteristics.
As the configuration, one end of a plurality of transmission paths prepared corresponding to the number of input / output ports is connected to each input / output port, and the other ends of the plurality of transmission paths are connected in common at a branch point. A first resistor having the same resistance value is connected in the middle of each transmission line. Further, a passive filter that removes a specific frequency band is connected between the branch point and the ground portion.

  According to the present invention, the configurations of the respective input / output ports viewed from the branch points connecting the respective transmission lines are equal, the impedance of each input / output port is made equal, and the signal in the desired frequency band is obtained by the action of the passive filter. Can be removed. And since there exists the 1st resistor connected in the middle of each transmission line, the signal strength transmitted between each input-output port can be made into appropriate intensity | strength.

  According to the present invention, it is possible to provide a signal transmission device capable of matching impedance between a plurality of ports and further removing a desired signal component.

Hereinafter, an example of the first embodiment of the present invention will be described with reference to FIGS.
First, the principle of the embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the signal distribution device according to the present embodiment includes six ports, and each port has a communication terminal (an antenna connection unit in the case of a wireless communication device) of a different communication device, either directly or Connected via signal line. The signal transmission apparatus according to the present embodiment makes the communication states of the communication apparatuses connected to the ports equal by setting all the six ports to equal signal characteristics.
The signal distribution device includes a wiring board 11. A signal transmission line 12 and a first attenuator are connected in series on the wiring board 11 to form a transmission line 17.

  One end of the transmission line 17 is connected to the port 10 (for example, port 1), and the other end is connected to the branch point 13. In the example of FIG. 1, six transmission lines 17 are commonly connected to the branch point 13. A second attenuator 15 connected to the ground is connected to the branch point 13. A filter 20 is further connected between the branch point 13 and the ground.

  A shield box 16 is formed so as to surround the wiring board 11 and the circuit, and the port 10 is installed outside the shield box.

  Next, FIG. 2 shows a more specific configuration example of the present embodiment. In the configuration example of FIG. 2, a series resistor 14 is connected corresponding to the first attenuator 14 of FIG. Further, as an example, a parallel resistor 15 is connected corresponding to the second attenuator 15 of FIG. The signal transmission line 12 may be a strip line or a microstrip line, for example.

  In the example of FIG. 2, the filter 20 of FIG. 1 is a circuit having a configuration in which a series inductance 21 and a series capacitance 22 are connected in series. In this example, one end of the series inductance 21 is connected to the branch point 13 and the other end is connected to the series capacitance 22 connected to the ground.

  The operation of the circuit shown in FIGS. 1 and 2 configured as described above will now be described. In the example of FIG. 2, a circuit having a desired attenuation factor can be formed by setting the values of the series resistor 14 and the parallel resistor 15.

When the value of the series resistor 14 is expressed as “rs”, the value of the series resistor 14 is N, the number of ports is K, the attenuation is K, and the characteristic impedance of the signal transmission line is 50Ω. Can be sought.
rs = 50 × (1−K) / (1 + K)

When the value of the parallel resistor 15 is expressed as “rp”, the resistance value rp (Ω) of the parallel resistor 15 can be obtained by the following equation.
rp = 100 * K / ((1 + K) * (1- (N-1) * K))

  The values of the series resistor 14 and the parallel resistor 15 are obtained by the above two equations. Further, the signal rejection band of the circuit is determined by the series inductance 21 and the series capacitance 22 connected to the branch point 13. The signal rejection band can be controlled by changing the values of the series inductance 21 and the series capacitance 22 to change the impedance.

  Therefore, for example, it is assumed that a wireless communication terminal (not shown in FIG. 2) is connected to each port and a signal is transmitted from the wireless communication terminal connected to port 1. In this case, the signal input to the port 1 is attenuated in signal strength by the attenuator 14 (series resistor 14) of the transmission path 17 and transmitted to the branch point 13.

  At the branch point 13, the signal is distributed with equal strength to the transmission path 17 connected to each port (port 2 to port 6). The signal is also distributed to the second attenuator (parallel resistor 15) connected to the branch point 13. The second attenuator 15 has the function of uniformly attenuating the entire signal transmitted to the other transmission path 17 in order to attenuate the intensity of the signal at the branch point 13.

  In the transmission line 17 connected to each port, the signal is further attenuated by the first attenuator 14, and the signal reaches each port (port 2 to port 6). Further, unnecessary signals are removed by a filter connected to the branch point 13.

  Therefore, in this example, by setting the values of the series resistor 14 and the parallel resistor 15, it is possible to configure a circuit having both distribution and attenuation functions and the same impedance when viewed from any port.

  In other words, impedance matching can be achieved at all ports without distinction between input ports and output ports. Further, since the signal attenuation between the ports, that is, the insertion loss is constant, each wireless communication apparatus can perform communication in the same communication state.

  Therefore, an environment equivalent to an actual wireless communication environment can be constructed. This is the same as the situation shown in FIG. In FIG. 3, four wireless communication terminals (wireless communication terminal 1 to wireless communication terminal 4) are wirelessly connected to each other with an attenuation factor of −50 dB.

  In an actual wireless communication environment, external noise or jamming waves will enter, but in the distributor according to this example, such an external noise or jamming wave is not present and an environment equivalent to the actual wireless communication environment must be realized. Can do.

  Further, if the circuit is formed as an IC (Integrated Circuit) chip, the apparatus can be reduced in size. As a result, there is no need to configure a circuit by complexly combining high-frequency components such as a distributor, attenuator, and terminator as in the prior art, and a wireless communication device to be evaluated can be connected to a distributor having the configuration shown in FIG. Terminal wireless communication evaluation and development system can be constructed.

  The series resistor 14 is connected to the signal transmission line 12 and formed on the wiring board 11. Therefore, the resistance value cannot normally be changed when a test or the like of the wireless communication terminal is performed. However, since the parallel resistor 15 is connected between the branch point 13 and the ground, a port connected to the branch point 13 can be newly provided and the resistance value can be changed by connection from the outside. Further, the parallel resistor 15 can be omitted.

  FIG. 4 shows a modification of the example of the first embodiment. FIG. 4 shows a configuration when the parallel resistor 15 of the signal distribution device shown in FIG. 2 is omitted. That is, as shown in FIG. 4, in addition to the series resistor 14, only the series inductance 21 constituting the filter 20 is connected to the branch point 13, and the parallel resistor 15 shown in FIG. Other parts are configured in the same manner as the signal distribution device of FIG. 2, and the description thereof is omitted. The resistance value rs of the series resistor 14 can be determined using the above formula.

  Regarding the operation of the circuit, the second attenuator 15 connected to the branch point 13 does not exist, but the signal of each transmission line 12 is uniformly attenuated by the first attenuator 14. Therefore, since it is the same as the example of FIG. 2, description is abbreviate | omitted.

Next, an example of the second embodiment of the present invention will be described with reference to FIG.
In FIG. 5, parts having the same configurations as those of the first embodiment are denoted by the same reference numerals. The configuration example of the present embodiment shown in FIG. 5 is an example in which four ports are installed. In each transmission line 17 connected to the port, a parallel circuit of a parallel inductance 23 and a parallel capacitance 24 is connected between the branch point 13 and the series resistor 14.

  In the example of the second embodiment, in addition to the filter 20 connected between the branch point 13 and the ground, a parallel circuit of a parallel inductance 23 and a parallel capacitance 24 between the transmission line 17 and the branch point 13 is used. Is connected. Therefore, the filter order of the pass band of the signal passing between the ports is fourth order.

  The operation of the distributor according to the example of the second embodiment will be described. FIG. 6 is a diagram showing signal characteristics of the circuit of FIG. In the figure, the horizontal axis represents the frequency, and the vertical axis represents the attenuation rate. As shown in the figure, the signal attenuation rate 30 has a flat characteristic in the vicinity of 0.10 GHzk to 0.7 GHz, and the signal transmission characteristic suddenly decreases from around 0.7 GHz, and at around 1.00 GHz. It is the minimum.

  That is, most of the signals near the frequency of 1 GHz flow to the ground by the filter 20 and are not transmitted into the circuit. Transmission characteristics increase rapidly from around 1.00 GHz to around 1.4 GHz, and have flat characteristics from around 1.4 GHz to 10.00 GHz.

  As can be seen from FIG. 6, a filter having a steep characteristic can be realized as the circuit characteristic in the example of the second embodiment. Therefore, it is suitable when the signal removal bandwidth is narrow.

Next, an example of the third embodiment of the present invention will be described with reference to FIG.
In FIG. 7, parts having the same configurations as those in the first embodiment are denoted by the same reference numerals. FIG. 7 is a configuration diagram showing an example of the third embodiment. As shown in the figure, two filters composed of a series inductance 21 and a series capacitance 22 are connected to the branch point 13. Here, for convenience of explanation, a filter composed of the series inductance 21 and the series capacitance 22 is referred to as a “first filter”, and a filter composed of the series inductance 25 and the series capacitance 26 is referred to as a “second filter”.

  Next, the operation of the circuit according to the example of the third embodiment will be described. By setting the resonance frequencies of the first filter and the second filter to different values, filters for two signal bands can be configured. The characteristics of the circuit according to the example of the third embodiment are shown in FIG. The horizontal axis of FIG. 8 is the signal frequency, and the vertical axis is the attenuation rate.

  The signal characteristic shows a substantially flat characteristic from a frequency of about 0.10 GHz to about 0.20 GHz, the transmission characteristic rapidly decreases from around 0.20 GHz, and becomes minimum at around 0.33 GHz. Transmission characteristics increase rapidly from the minimum point near 0.33 GHz to near 0.50 GHz.

  The characteristics are almost flat from about 0.50 GHz to about 2 GHz, and the transmission characteristics decrease rapidly from about 2 GHz to about 2 GHz, and take a minimum value. The transmission characteristic increases rapidly from around 2 GHz to around 4 GHz, and becomes almost flat from around 4 GHz to 10 GHz.

  When two filters having different resonance frequencies are provided at the branch point 13 in this way, two signal removal bands are also set. That is, if the resonance frequency is set to a different value, the signal removal band is set by the number of filters connected to the branch point 13.

  Therefore, when there are a plurality of frequency bands to be removed, a necessary number of filters may be provided between the branch point 13 and the ground.

It is the conceptual diagram which showed the structure of the example of the 1st Embodiment of this invention. It is the block diagram which showed the specific circuit example of the example of the 1st Embodiment of this invention. It is the block diagram which showed the actual communication environment equivalent to the example of the 1st Embodiment of this invention. It is the block diagram which showed the modification of the example of the 1st Embodiment of this invention. It is the block diagram which showed the example of the 2nd Embodiment of this invention. It is a characteristic view of the example of the 2nd Embodiment of this invention. It is the block diagram which showed the example of the 3rd Embodiment of this invention. It is a characteristic view of the example of the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Port, 11 ... Wiring board, 12 ... Signal transmission line, 14 ... 1st attenuator, 15 ... 2nd attenuator, 16 ... Shield box, 20 * ··filter

Claims (4)

A signal distribution device comprising at least three input / output ports, each of the input / output ports having the same characteristics,
A plurality of transmission lines corresponding to the number of the input / output ports, each having one end connected to the input / output port,
A first resistor having an equal resistance value and connected in the middle of the plurality of transmission lines;
A branch point commonly connected to the other ends of the plurality of transmission lines;
A signal distribution device comprising: a passive filter connected between the branch point and the ground portion and configured to remove a specific frequency band. The signal distribution device according to claim 1, wherein a second resistor is connected between the branch point and the ground portion. The signal distribution device according to claim 1, wherein filters having the same characteristics are connected between the other ends of the plurality of transmission lines and the branch point. The signal distribution device according to claim 1, wherein the passive filter connected between the branch point and the ground unit includes a plurality of passive filters having different frequency bands to be removed.

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