JPH0514575Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a terminator, particularly a terminator for a coaxial cable when transmitting high-speed pulse signals using a coaxial cable.

[Technological environment]

In recent years, digital circuits have tended to become faster with advances in integrated circuit elements, and coaxial cables are used to transmit high-speed pulses, and terminators are used to terminate the transmission.

[Common technology]

Generally, a low resistance resistor of 50 [Ω] or 75 [Ω], which is equal to the characteristic impedance of the coaxial cable, is used as a terminator. This is to prevent the reflected wave from being sent back from the termination point to the sending end by completely absorbing it and converting it into heat. However, in integrated circuit elements for high-speed digital circuits, 50
Directly driving a terminating resistor with a value of [Ω] to 70 [Ω], which is close to a short circuit, is generally done by inserting a bias power supply in series with the terminating resistor as a terminating circuit, because heat generation is limited by the power consumption of the integrated circuit itself. do,
It is necessary to maintain the amplitude of the pulses to be transmitted equal to the logic level of the integrated circuit used and to reduce the power supplied to the termination resistor. For example, ECL
(Emitter Coupled Logic) The case of an integrated circuit logic element is shown in FIG.

In Figure 3, 9 and 10 are based on the ECL circuit.
NOR logic element, 11 is the center line of the coaxial cable,
12 is the jacket wire of the coaxial cable, 8 is the terminating resistor,
13 is a bias power supply.

Usually, in the ECL circuit element, the value of the terminating resistor 8 is 50 to 75 [Ω], which is equal to the characteristic impedance of the coaxial cable 10 used, and the voltage value of the bias power supply 9 is -2 [V].

Also, when observing the pulse waveform at the terminal point,
As shown in the electrical circuit diagram in Figure 4, the oscilloscope 14
A terminating resistor 8 and a bias power supply 13 are connected in series between the input terminal and the input ground terminal.

[Conventional technology]

A conventional terminator includes two coaxial connectors each having a center contact and a jacket contact connected to each other, and a resistor having both ends connected to the center contact and jacket contact of the coaxial connector, respectively.

Next, a conventional terminator will be described in detail with reference to the drawings.

FIG. 2 is an electrical circuit diagram of a conventional terminator.

The terminator shown in FIG. 2 includes two coaxial connectors 1, 2 and a resistor 8. Here, since the coaxial connector 1 is normally connected to a coaxial cable to be terminated, a female type is used. The other coaxial connector 2 is a male type so that it can be connected to a high input impedance, input signal coaxial connector of an oscilloscope during waveform observation.

The resistor 8 is normally equal to the characteristic impedance value of the coaxial cable connected to this terminator.
50 [Ω] or 75 [Ω] is used.

[Problem that the invention attempts to solve]

The conventional terminator described above has the disadvantage that it cannot be used as a terminator for coaxial cables that need to be terminated through a bias power source because the center contact and outer sheath contact of the coaxial connector are directly connected with a resistor. Ta.

[Means for solving problems]

The terminator of the present invention includes two coaxial connectors each having a center contact and a sheath contact connected to each other, a battery having one power source connected to the sheath contact of the coaxial connector, and one fixed contact connected to the outside of the coaxial connector. A variable resistor is connected to the contact point and the other fixed contact is connected to the other electrode of the battery, a movable contact is connected to the check terminal and the movable contact of the variable resistor, and one fixed contact is connected to the coaxial connector. and a capacitor having one electrode connected to the check terminal and the other electrode connected to the jacket contact of the coaxial connector.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an electrical circuit diagram showing one embodiment of the present invention.

The terminator shown in FIG. 1 consists of two coaxial connectors 1 and 2, each having a center contact and an outer sheath contact connected to each other, a battery 3 whose one electrode is connected to the outer sheath contact of the coaxial connectors 1 and 2, and one fixed a variable resistor 4 whose contacts are connected to the jacket contacts of the coaxial connectors 1 and 2, and whose other fixed contact is connected to the other electrode of the battery 3;
Then, one electrode is connected to another variable resistor 5 whose moving contact is connected to the check terminal 7 and the moving contact of the variable resistor 4, and one fixed contact is connected to the center contact of the coaxial connectors 1 and 2. Connect the other electrode to the check terminal 7 and connect the other electrode to the coaxial connector 1,
The device includes a capacitor 6 connected to the outer sheath terminal of No. 2.

Here, the check terminal 7 in FIG. 1 is a terminal for checking the termination resistance value necessary for this terminator and the voltage value of the internal bias power supply, and the variable resistor 4 is a terminal for making the voltage value of the internal bias power supply variable. The variable resistor 5 is for varying the termination resistance value, and the battery 3 is for internal bias voltage, and the battery is used to make this terminator portable, small, lightweight, and easy to handle.

Capacitor 6 is for bypassing high frequency signals.

Variable adjustment of the variable resistor 4 is carried out by setting a necessary internal bias voltage value while measuring the voltage value between the jacket contact of the coaxial connector 1 or 2 and the check terminal 7 with a voltmeter. Further, variable adjustment of the variable resistor 5 is performed by setting the internal resistance value to a required value while measuring the resistance value between the center contact of the coaxial connector 1 or 2 and the check terminal 7 with a resistance meter.

By setting the two variable resistors 4 and 5 in this way, the necessary bias voltage and the necessary high frequency termination impedance can be obtained between the center contacts and the outer sheath contacts of the coaxial connectors 1 and 2.

[Effect of idea]

By installing a battery and a variable resistor inside the terminator of this invention, it is possible to realize any internal bias voltage at the end, so it can be directly applied to the outer sheath of the coaxial cable for transmitting output signals of ECL logic circuit elements, etc. This has the effect that it can be used as a terminator for coaxial cables of arbitrary impedance by providing another variable resistor and a bypass capacitor.

Furthermore, since it uses batteries, it is small and lightweight, so it has the advantage of being easy to handle, such as being portable.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit diagram showing an embodiment of the present invention;
Figure 2 is an electrical circuit diagram showing an example of the conventional method, and Figure 3 is
Circuit diagram using ECL, Figure 4 is a circuit diagram when using an oscilloscope. 1, 2... Coaxial connector, 3... Battery, 4, 5
... Variable resistor, 6 ... Capacitor, 7 ... Check terminal, 8 ... Resistor, 9, 10 ... ECL element, 11 ... Center line of coaxial cable, 12 ... Outer wire of coaxial cable, 13...Bias power supply, 1
4... Synchronoscope.

Claims (1)

[Scope of utility model registration request] two coaxial connectors each having a center contact and a sheath contact connected to each other; a battery having one electrode connected to the sheath contact of the coaxial connector; and a battery having one fixed contact connected to the sheath contact of the coaxial connector and the other. A variable resistor having a fixed contact connected to the other electrode of the battery, and another variable resistor having a moving contact connected to a check terminal and the moving contact of the variable resistor, and one fixed contact connected to the center contact of the coaxial connector. one variable resistor and one electrode connected to the check terminal,
A terminator comprising a capacitor having the other electrode connected to a jacket contact of the coaxial connector.