JPS6219087B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a broadband multi-directional branching device using amplifiers having low output impedance and low input impedance at the receiving end and the transmitting end, respectively.

In general, various branching methods are employed to effectively and economically construct various wideband frequency division multiplexed signal transmission lines depending on the purpose of the transmission line. When there are transmission lines in multiple directions at a given relay point, it is normal to have multiple conversion branches for each direction, but if the same frequency band can be used in common in multiple directions, it is better to omit this conversion device. It can be replaced with an economical branching device. Conventionally, hybrid transformers have been used to branch or combine these broadband multiplexed signals. As such a hybrid transformer, a pseudo impedance is connected to one of the four terminal pairs of a three-turn transformer, which is composed of three windings wound around the same iron core, and one-to-two branching and coupling are performed. A balanced type that can perform the 2, which is grounded through the terminal and branched or connected to both ends of the secondary winding.
Output or input two signals, split 1 to 2,
There is an unbalanced type that allows for binding. In order to be able to perform branching and coupling in a ratio of 1:3 or more, it is necessary to divide this into n stages, perform branching and coupling at a ratio of 1: ²ⁿ , and then connect pseudo impedances to unnecessary terminals. . When performing multi-directional branching, the first disadvantage is that due to the characteristics of wideband hybrid transformers, the transmission characteristics deteriorate when connected in multiple stages, and the second disadvantage is that multi-directional bidirectional branching circuits are configured. In this case, the amount of unbalanced attenuation of the hybrid transformer is limited for a wide range of frequencies, and wraparound crosstalk occurs due to the impedance of the circuits connected in each direction. In other words, when using a hybrid transformer, the input and output impedance is 75 ohms, so the degree of freedom in matching with the characteristic impedance of the transmission line is small, and for this reason, it is necessary to attenuate to suppress crosstalk. It has the disadvantage of requiring the use of a power converter and an amplifier, which increases the cost of the hardware configuration.Also, stray capacitance, leakage inductance, etc. become a problem when branching high frequency signals, and compensation means must be added. It was hot.

The present invention improves the conventional drawbacks as described above, and combines a circuit consisting of a low output impedance amplifier, a low input impedance amplifier, and a plurality of matching resistors provided at the output or input of the amplifier into a branch circuit and a combination. By using it as a circuit,
It is an object of the present invention to provide a wideband multiplex signal branching/coupling device that improves characteristics such as wrap-around attenuation and frequency characteristics, increases the number of branching/coupling, and simplifies the configuration. Examples will be described in detail below.

FIG. 1 is an explanatory diagram of an example of a line configuration to which the present invention is applied. In the same figure, the communication terminal stations A and B are branch points, and communication between A ₁ and B is made through a common transmission path.
It is assumed that ₃ stations A, ₁ station B, and ₃ stations B communicate arbitrarily in both directions. That is, communication terminal A
Branch coupling parts a and b are provided in the station and B station, respectively.
A ₁ station ~ Each branch coupling part of A ₃ stations a ₁ ~ a ₃ and B ₁ station ~
Connections shown by dotted lines are made between each of the branch coupling parts b ₁ to _{b 3} of the three stations B and between each other, and a common transmission line 1 shown by a solid line is provided between the branch coupling parts a _and b of stations A and B. Further, the round-trip communication system can be further connected to arbitrary stations such as A ₁ and B _1.
A circular communication system can also be constructed by providing a common transmission path 2 shown by dotted lines between the stations.

FIG. 2 is a schematic explanatory diagram of an embodiment of the present invention using the line configuration shown in FIG. In the same figure, 1 within the broken line
0, 20 indicate the corresponding A station, B station, 11,
21 is a branching/coupling device which is the essential part of the present invention.
Transmission is performed for the common transmission path 1 through the branching/coupling units a, b and multiplex transmission devices (M) 12, 22, and from the branching/coupling unit 11 to the branching/coupling unit a for stations _A1 to _A3 . ₁ ~ a ₃ from A station's transmission device 13 ₁ ~
₁₃ Transmission device 1 of _A1 station to A3 station via ₃ respectively
4 ₁ to 14 ₃ , and is transmitted from the branching/coupling device 21.
For the B ₁ to B ₂ stations, the branching/coupling units b ₁ to b ₃ transmit data to the B ₁ to B 3 transmission devices 24 ₁ to _{24 3} via the B station transmission devices 23 ₁ to 23 ₃ , respectively. be done. Also, as in FIG. 1, the common transmission path 2 is constructed between the transmission device 14 ₁ of the A ₁ station and the transmission device 24 ₁ of the B ₁ station.

FIG. 3 is a block diagram of a main part of an embodiment of the present invention, and is related to the branching and coupling device 11 shown in FIG. In the figure, 30 ₀ to 30 ₃ are receiving ends;
30' ₀ ~ 30' ₃ is the transmitting end, 31 ₀ ~ 31 ₃ and 3
1' ₀ to 31' ₃ are a low output impedance amplifier and a low input impedance amplifier respectively constructed of active elements such as transistors; 32 ₀ ;
32' ₀ to 32 ₃ , 32' ₃ is a matching resistor, 33 ₀
33 ₃ is a switch circuit, 41 and 42 are matrix switch circuits, 43 is a switch control circuit, and a, a ₁ to a ₃ correspond to the branch coupling parts with the same symbols in FIGS. 1 and 2. . _For example, a signal applied to the receiving end ₃₀₀ is branched into three parts by a matching resistor 320 from an amplifier ₃₁₀ with low output impedance, a matrix switch circuit 41, a matching resistor _32'1 , and an amplifier 3 with low input impedance.
_1'1 to the transmitting end _30'1 , matrix switch circuits 41, 42, matching resistor _32'2 ,
The transmitting end 30' ₂ is connected to the transmitting end 30' ₂ via the low input impedance amplifier 31' 2, and the transmitting end 30' 3 is connected to the transmitting end 30' ₃ via the matrix switch circuits 41 and 42, the matching resistor 32' ₃ , and the low input impedance amplifier 31' ₃ .
will be sent to. The other receiving end and transmitting end are connected via a matrix switch circuit or the like in the same way as described above.

The switch control circuit 43 controls the matrix switch circuits 41 and 42 using the switch control signal extracted from the received signal in each direction or the switch control signal via the dedicated control line, and the switch circuits 33 ₀ to 33
By controlling the on/off of _T.333 etc., broadband multiplexed signals from any direction can be exchanged and transmitted in a predetermined direction simultaneously or in a time-division manner. Therefore, it is of course possible to connect in a connection relationship other than the connection configuration shown.

Methods of lowering the output impedance or input impedance of an amplifier are well known. To lower the output impedance, for example, use a transistor as an emitter follower, and to lower the input impedance,
All you have to do is return. The output impedance or input impedance of such an amplifier is, for example, about 1 ohm or less, so matching can be achieved with a transmission line of any impedance using a matching resistor, making it easy to suppress crosstalk. , and a large number of branches or connections can be easily made through matching resistors.

As explained above, the present invention provides amplifiers 31 ₀ to 31 ₃ , 31 ′ with low output impedance and low input impedance at the receiving end and the transmitting end, respectively.
By using ₀ to _31'3 , a matching resistor _320,3 for branching or coupling is provided on the output side or input side.
Even if 2' ₀ to 32 ₂ and 32' ₃ are connected for branching or coupling, the common connection point of the matching resistors has low impedance, so there is no signal looping around, thereby preventing crosstalk. be able to.
In addition, the matrix switch circuits 41 and 42 allow switching transmission in any direction, so multi-directional branching,
The combination can be done economically.

Therefore, compared to conventional branching and coupling devices using hybrid transformers using windings, it is easier to branch and couple high frequency signals, ensure high quality transmission characteristics, and reduce the number of branches and couplings. can also increase.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an example of a line configuration to which the present invention is applied, Fig. 2 is a schematic explanatory diagram of an embodiment of the present invention using the line configuration of Fig. 1, and Fig. 3 is a main part of the embodiment of Fig. 2. It is an explanatory diagram showing the configuration of 10, 20 in the figure.
is a communication terminal station, 11, 21 is a branching and coupling device, 12,
22 is a multiplex transmission device, 13 ₁ to _{13 3} , 14 ₁ to
14 ₃ , 23 ₁ to 23 ₃ , 24 ₁ to 24 ₃ are transmission devices, 30 ₀ to 30 ₃ are receiving ends, 30' ₀ to 3
0' ₃ is the transmitting end, 31 ₀ to 31 ₃ , 31' ₀ to 3
1' ₃ is an amplifier with low output impedance and low input impedance, 32 ₀ to 32 ₃ , 32' ₀ to 3
Reference _{numeral 2'3} indicates a branch coupling matching resistor, ₃₃₀ to ₃₃₃ are switch circuits, 41 and 42 are matrix switch circuits, and 43 is a switch control circuit.

Claims (1)

[Claims] 1. A matrix switch circuit connected to the receiving end and the transmitting end and performing exchange transmission using amplifiers and switch control circuits with low output impedance and low input impedance, respectively, and a matrix switch circuit with the low output impedance connected to the receiving end. Connected between the output side of the amplifier and the matrix switch and between the input side of the low input impedance amplifier connected to the transmitting end and the matrix switch to perform branching and coupling and prevent wraparound crosstalk. A broadband multi-directional branching and coupling device characterized by being equipped with a matching resistor.