JPS63194413A - Pulse signal deliver circuit - Google Patents

Abstract

PURPOSE:To realize the compression of a circuit scale and the reduction of a price and to easily perform the successive and variable adjustment of the amplitude of an output pulse, by obtaining a pulse output from the secondary side output terminal of a transformer, by connecting the output of a logic IC to the anode of a first diode and the one end of a variable resistor, and connecting the other end of the variable resistor to the anode of a second diode. CONSTITUTION:A transistor 2 is turned ON when the logic IC6 is set at an 'H' level, and goes to an OFF state when it is set at an 'L' level, and to the primary side of the transformer 1, a collector voltage at respective state is inputted, and at the secondary side output, the output pulse to be sent to a transmission line appears. And potential V1 at a point B is increased when the value of the variable resistor 8 is set at a large value, then, the amplitude of the output pulse is decreased. Also, the potential is decreased when that of the variable resistor 8 is set at a small value, and also, the amplitude of the output pulse is increased. Thus, since the amplitude of the output pulse can be adjusted successively by adjusting the variable resistor 8, it is possible to make an ATT circuit being provided at the secondary side of the transformer in a conventional circuit unnecessary.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pulse signal sending circuit in a digital transmission system, in particular, to send a pulse signal to a transmission line by driving a transformer at a constant voltage by turning on and off a transistor. It relates to a pulse signal output path.

(Prior Art) Generally, in a digital transmission system, a pulse signal sending circuit for sending out a pulse signal is incorporated into a transmission path, and the pulse signal is sent out while limiting the pulse signal amplitude and occupancy within a certain standard. As a conventionally commonly used transmission circuit,
The circuit illustrated in FIG. 2 is known, and one of the transformers 1
The secondary side of the transformer 1 is driven at a constant voltage by turning on and off the transistor 2, and the secondary side of the transformer 1 is connected to a variable resistance attenuator (hereinafter referred to as
(referred to as ATT) 3 is provided, and fluctuations in the sending pulse amplitude due to variations in the diodes 4, 5, the transistor 2, and the transformer 1 are adjusted to send out pulses within a certain standard. Here, 6 is a general logic IC, and 7 is a resistor provided between the diode 4 and ground.

(Problems to be Solved by the Invention) In the conventional circuit shown in FIG. 2, since fluctuations in pulse amplitude due to variations in the 22-power circuit elements are adjusted by the ATT 3, the following problems occur.

First, since the ATT must be a constant resistance circuit with the same impedance as the characteristic impedance of the transmission line, the circuit configuration is different from a simple circuit such as a normal resistance voltage divider, for example, a T-type or π-type. The circuit becomes complicated, the circuit scale becomes large, and the price becomes expensive. Second, in the above-mentioned ATT, it is impossible to change the attenuation amount continuously due to the circuit configuration, and the attenuation amount changes in a stepwise manner, since the switching selection method usually takes several steps, and the output pulse cannot be accurately adjusted within a certain standard, and when adjusting more accurately, the number of variable steps must be increased, resulting in a fairly large implementation scale and making the ATT itself quite expensive.

It is an object of the present invention to provide a pulse signal sending circuit which eliminates the first and second problems mentioned above, has a smaller circuit scale than the conventional one, is cheaper than the conventional one, and is capable of continuously variable adjustment of the output pulse amplitude. It is in.

(Means for Solving the Problems) The pulse signal sending circuit of the present invention transmits the output of the logic IC to the first
Connect the anode of the diode and one end of the variable resistor,
A cathode of the first diode is connected to one end of a resistor and a base of a transistor, the other end of the resistor and an emitter of the transistor are grounded, and the other end of the variable resistor is connected to an anode of a second diode. The cathode of the second diode is connected to the collector of the transistor and also to the primary input terminal of the transformer, so that a pulse output is obtained from the secondary output terminal of the transformer.

(Example) Next, the present invention will be explained by way of example with reference to the drawings.

FIG. 1 is a block diagram of a pulse signal sending circuit according to an embodiment of the present invention. In this embodiment, the output of the logic IC 6 is connected to the anode of the first diode 4 and one end of the variable resistor 8, the cathode of the first diode 4 is connected to one end of the resistor 7 and the base of the transistor 2, The other end of the resistor 7 and the emitter of the transistor 2 are grounded, the other end of the variable resistor 8 is connected to the anode of the second diode 5, and the cathode of the second diode 5 is connected to the collector of the transistor 2. Connect and transformer 1
It is connected to the primary side input terminal of.

In this circuit with such a configuration, the logic IC6 is #H#
Transistor 2 is turned on when the level is low, and turned off when it is low, and the collector voltage at each state is applied to the primary side of the transformer 1, which is the so-called constant voltage drive type of the transformer 1. and transformer 1 and 2
An output pulse for sending out to the transmission line appears at the next output.

The potential V+ at point B when transistor 2 is off is equal to the transformer supply voltage (vcc), and when transistor 2 is on, V+ is equal to the voltage drop due to the current flowing between points A and B, that is, (rxRV t v o 2 , where V
D2 is clamped at the voltage drop of D2).

That is, when the variable resistor 8 becomes large, Vl becomes large and the output pulse amplitude becomes small. Further, when the variable resistor 8 becomes small, Vl becomes small and the output pulse amplitude becomes large.

By adjusting the variable resistor 8 in this manner, the output pulse amplitude can be adjusted continuously, so that the ATT circuit conventionally provided on the secondary side of the transformer becomes unnecessary.

(Effects of the Invention) As explained above, according to the present invention, the pulse signal sending circuit, which conventionally used an expensive and large-scale ATT and was unable to perform complete amplitude adjustment, can be replaced with an inexpensive and small-scale circuit. Moreover, the present invention has the advantage that it can be provided as a pulse signal sending circuit that allows complete amplitude adjustment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a pulse signal sending circuit according to an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional pulse signal sending circuit. DESCRIPTION OF SYMBOLS 1... Transformer, 2... Transistor, 3... Variable resistance attenuator (ATT), 4... First diode, 5... Second diode, 6... Integrated logic IC17. ...Resistance, 8...Variable resistor. Agent Patent Attorney Toshiyoshi Somekawa Figure 1 Figure 2 VC [

Claims (1)

[Claims] The output of the logic IC is connected to the anode of the first diode and one end of the variable resistor, the cathode of the first diode is connected to one end of the resistor and the base of the transistor, and the other end of the resistor and the emitter of the transistor are connected. are respectively grounded, the other end of the variable resistor is connected to the anode of a second diode, the cathode of the second diode is connected to the collector of the transistor and to the primary input end of the transformer, A pulse signal sending circuit characterized in that a pulse output is obtained from a secondary output end of the transformer.