JPS62243427A - Bipolar signal drive circuit - Google Patents

Abstract

PURPOSE:To simplify the circuit and to reduce the power consumption by adopting the constitution that the beta effect characteristic of a transistor (TR) is utilized and a specific impedance is caused at no signal. CONSTITUTION:In the operation where a bipolar signal of +1 level is caused at output terminals A,B when an input signal is logical '1', a control signal is applied from a control circuit 14 so as to turn respectively on/off/off/on/off/off TRs 3,6,9,10,15,16. In this case, a current flowing to a laod resistor 13 from a DC power supply 1 via the TR 3 is short-circuited by the TR 10 and a +1 voltage E0 is generated at a resistor 13. A-1 voltage is generated similarly. When the input signal is '0', the current flowing from the collector to the emitter of the TR 15 by a bipolar signal flows from the emitter to the collector of the TR 16 by the beta effect of the TRs and then flows to a resistor 18. Similarly, a current flows to a resistor 17. The output impedance becomes a specific value depending on the resitors 17,18 and the on-resistance of the TRs 15, 16.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention is a bipolar signal that converts a unipolar (for example, 1.0) input digital signal into a multipolar (for example, +1.-1°0) bipolar signal. The present invention relates to signal drive circuits, and particularly to improvements to simplify the circuit configuration thereof.

[Conventional technology]

FIG. 4 is a circuit diagram showing an example of a conventional bipolar signal drive circuit. In the figure, 1 is a DC power supply with an output voltage of E as a bipolar signal source, and 2 is an input signal for the bases of transistors 3, 4.5, 6.7.8 degrees 9 and 10 to drive them. Control circuit as control means created from digital signals, 11.1
2 is a resistor, and the sum of these resistors 11 and 12, the on-resistance (internal resistance) value of NPN transistor 4 or 7, and the on-resistance (internal resistance) value of PNP transistor 5 or 8 is the It is a resistance that acts as an impedance. Here, a bipolar signal generating means 100 is constituted by the DC power supply 1, transistors 3 to 10, and resistors 11 and 12.

FIG. 5 is a state diagram showing the operating states of the transistors 3 to 10 when outputting ±1.0 symbols of the bipolar signal from 1.0 symbol of the digital signal input to the control circuit 2 shown in FIG. 4. .

Next, FIGS. 4 and 5. See diagram? Above, the principle of bipolar signal generation and the output impedance at the time of generation will be explained. First, an explanation will be given of the operation when a +1 symbol is generated as an output bipolar signal when the symbol of the digital signal input to the control circuit 2 is 1. In this case, transistors 3, 4, 5, 6, 7, 8, 9 and 10 are turned on as shown in
.

OFF, OFF, OFF, OFF, O
FF.

A control signal is applied from the control circuit 2 to turn it OFF and ON. Then, the DC power supply 1 is applied to the load resistor 13 having a resistance value R through the transistor 3. Load resistance 13
The current passing through is short-circuited by the resistor 10. As a result, a +1 symbol [+E (volt)] is generated at both ends of the load resistor 13. The output impedance in this case is the sum of the on-resistance values of transistors 3 and 10.

The −1 symbol is also generated according to the operation pattern of the transistor shown in FIG. 5, as described above. The output impedance at this time is the sum of the on-resistance values of transistors 6 and 9. On the other hand, when digital number 14 input to input control circuit 2 is a 0 symbol, transistors 3, 4, 5, 6, 7, 8, 9 and 10 are turned off and turned on, respectively.

Turn ON, OFF, ON, ON, OFF, OFF. At this time, the DC power supply 1 is not applied to the load resistor 13, and an O symbol [0 (volt)] is generated. Also, the output impedance at that time is the sum of the resistance values of resistors 11 and 12 and the on-resistance values of NPN transistor 4 or 7 and PNP transistor 5 or 8, and when a bipolar signal is received from the load side, a specific becomes impedance.

Since the conventional bipolar signal drive circuit is configured as described above, two fixed resistors and two NPN I-
Since a transistor and two PNP transistors are required, the circuit becomes very complicated, and there are other problems such as the need for two control signals. Furthermore, when the circuit shown in FIG. 4 is integrated, there is a problem in that reactive current flows due to the parasitic diode of the PNP transistor, resulting in extremely high power consumption.

This invention was made to solve the above-mentioned problems, and it is possible to simplify the circuit so that it can be terminated with a specific impedance when there is no signal, thereby obtaining a bipolar signal drive circuit with low power consumption. The purpose is to

[Means for solving problems]

A bipolar signal drive circuit according to the present invention is a bipolar signal drive circuit comprising a signal generation means 100 that generates a bipolar signal at both ends of a load resistor 13 according to an input digital signal.
a first transistor 3 or 6 which is controlled by the control means 2 to generate the bipolar polarity at its output terminal;
The signal generation circuit 100a and 100b each include a transistor 15 or 16 and a third transistor 9 or 10.

[Effect]

The signal generating means 100 according to the present invention generates a bipolar signal of the "zero" symbol from the signal generating circuits 100a and 100.
The circuit can be simplified since it is generated by only transistors 15 and 16 of each year 0b and two resistors 17 and 18.

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 is a bipolar signal source, which is a single DC power supply that generates an output voltage E with respect to an input terminal C;
are NPN transistors 3, 6°9, 10, 15 and 1
A control circuit (control means) that creates a control signal for driving 6 from a digital signal as an input signal, 17 and 18 are resistors, and the resistance value Roll R22,
The sum of the on-resistance values of transistors 15 and 16 is
It is a resistance that has a specific impedance. In other words, this embodiment has a series circuit of a DC power supply 1, a transistor 3 (or 6) as a first transistor, and a transistor 1 as a second transistor with its emitter short-circuited.
5 (or 16) and resistor 17 (or 18
) and transistor 9 (or 10) as a third transistor whose emitters are shorted are connected in parallel to form a signal generation circuit 1008 (or 100b).
Two systems are provided to constitute the signal generating means 100, and each output terminal is used as an output terminal for a bipolar signal.

FIG. 2 shows ±1.0 of the bipolar signal from 1.0 symbol of the digital signal input to the control circuit 14 shown in FIG.
Transistors 3, 6, 9 when outputting symbol husband
．． 10.15. and 16 are state diagrams showing the operating states of FIG.

In general, the static characteristics of an NPN transistor are expressed as shown in FIG. 3, and a characteristic called a beta effect is obtained when the collector-emitter voltage Vc and the collector current Ic are each in the negative range. This embodiment actively utilizes this characteristic.

Next, the principle of bipolar signal generation and the output impedance at that time will be explained with reference to FIGS. 1 and 2. First, when the symbol of the input decile signal is 1 as shown in FIG. Second output terminal A, B
The operation of generating the +1 symbol of the bipolar signal will be explained below.

In this case, as shown in FIG.
．． 10. Turn on 15 and 16 respectively.

A control signal is applied from the control circuit 14 so that the states are OFF, OFF, ON, OFF, OFF. At that time, the DC power supply 1 is applied from the transistor 3 to the load resistor 13 having a resistance value R via the output terminal A. The current passing through the load resistor 13 is short-circuited by the transistor 10 via the output terminal B, and an Eo of +1 symbol is generated in the load resistor 13.

In this case, the output impedance is the sum of the on-resistances (internal resistances) of transistors 3 and 10. Similarly to the above explanation, the -1 symbol is also generated according to the state diagram showing the transistor operating state in FIG. 2, and the output impedance is the sum of the on-resistance values of transistors 6 and 9.

On the other hand, when the input digital signal is a 0 symbol, transistors 3, 6, 9, 10, 15 and 16 are OFF, OFF, OFF, OFF, respectively.

It becomes ON, ON state. At this time, the DC power supply 1 is not applied to the load resistor 13, and a 0 symbol (ie, 0 (volt)) is generated. In this case, when a bipolar signal is received from the load side, it passes through the resistor 17.

The current that flows from the collector to the emitter of transistor 15 flows from the emitter to the collector of transistor 16 and passes through resistor 18 due to the beta effect of the transistor. Similarly, the current flowing from the collector to the emitter of transistor 16 passing through resistor 18 is
5 flows through the collector and passes through the resistor 17.

Therefore, the output impedance is the resistance value R2M of the resistor 17.
The resistance value &2 of the resistor 18 becomes the on-resistance of the transistors 15 and 16, resulting in a specific impedance.

In addition, in the above embodiment, in order to obtain a specific impedance when generating a 0 symbol as a symbol of an output bipolar signal or when receiving a bipolar signal from the load side, the resistors 17 and 18 are connected to the second resistor. , transistors 15 and 16, but instead of resistors 17 and 18, one resistor with a resistance value equal to the sum of their respective resistance values R2 and IV and transistors 15 and 16 provide a specific impedance. The circuit may be configured so that

〔Effect of the invention〕

As described above, according to the present invention, the signal generating means is configured to generate a specific impedance when there is no signal by utilizing the beta effect characteristics of the transistor, so the circuit has a simple configuration and can be implemented as an IC. This has the effect of providing a bipolar signal drive circuit with low power consumption.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a bipolar signal drive circuit according to an embodiment of the present invention, FIG. 2 is a state diagram for explaining the operation of the above embodiment, and FIG. A characteristic diagram for explaining effect characteristics, FIG. 4 is a circuit diagram showing the configuration of a conventional bipolar signal drive circuit, and FIG. 3 is a state diagram for explaining the operation of FIG. 1...DC power supply, 3, 6, 9.10. ．． 15°16・
...Transistor (first to third transistor), 13
...Load resistance, 14...Control circuit (control means), 1
7.18...Resistor, 100...Signal generation means, 10
0a, 100b...signal generation circuit, A, B...output end, C...input end. In the drawings, the same reference numerals indicate the same or equivalent parts. Agent Masuo Oiwa (and 2 others) Figure 1

Claims (2)

[Claims] (1) Signal generation means that uses a single DC power supply as an input signal and generates bipolar signals of +1, -1, and zero symbols across a load resistor, and a predetermined digital signal as input, and responds to the digital signal. and a control means for controlling the signal generation means, the bipolar signal drive circuit comprising:
The signal generating means includes first and second output terminals connected correspondingly to both ends of the load resistor, and an input terminal connected to the DC power supply and into which an input signal from the power supply is input, a first transistor that outputs an input signal at the input terminal to the first and second output terminals based on an ON command from the control means; and a second transistor that supplies earth air to the first and second output terminals. , the above-mentioned first,
A bipolar signal, characterized in that a signal generating circuit comprising a third transistor applied to the second output terminal is provided between the input terminal and the first output terminal, and between the input terminal and the second output terminal. drive circuit. (2) The bipolar signal drive circuit according to claim 1, wherein the first and second transistors are NPN transistors.