JPS6268322A - Bipolar signal drive circuit - Google Patents

Abstract

PURPOSE:To supply a DC power without using a signal transformer and to obtain a circuit realizing a semi-matching drive by providing a switch means giving a DC power supply to an output terminal connected with a load resistor based on an output of a control means and short-circuiting the output terminal to a signal generating means. CONSTITUTION:A switch means consists of analog switches 13-18 and a signal generating means A is constituted by providing two systems of circuits each comprising a series circuit consisting of a DC power supply 1 and a switch 13 or 16, a series circuit consisting of a switch 14 or 17 whose one terminal is short-circuited and a resistor 19 or 20 having a half value of a load resistor 10 and a circuit consisting of parallel connection of a switch 15 or 18 whose one terminal is short-circuited, and each output point is used as an output terminal 0 of a bipolar signal. In the circuit above, the DC power supply 1 as a bipolar signal source is not fed via a signal transformer but fed to the load resistor 10 via a switch 13 or 16 directly. Further, the current fed back from the load resistor 10 is short-circuited via a switch 18 or 15 to generate a bipolar signal across the load resistor 10.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention converts a unipolar input digital signal consisting of 1.0 symbols into a multipolar input signal consisting of ±1.0 symbols in order to eliminate DC components in a transmission path. The present invention relates to a bipolar drive circuit that converts a polar output bipolar signal, and particularly relates to an application method of a DC power source as a bipolar signal source and an output impedance of a bipolar signal.

[Prior Art] FIG. 3 is a circuit diagram showing an example of a bipolar signal drive circuit according to the prior art. In the figure, ■ is a DC power supply with an output voltage of E (volts), which is the signal source for creating the +1 symbol of the bipolar signal, and 2 is an analog switch (hereinafter abbreviated as switch) made of a transistor, etc. 3, 4.5
7 and 8 are resistors having a value twice the resistance value R (ohm) of the load resistor 10, and 9 is a primary winding. This is a signal transformer with a winding ratio of 2:1, in which a DC type tX1 is connected to the midpoint of the transformer, and the load resistor 10 is connected to the output terminal 0 of the secondary winding.

Here, the above 1.3 to 9 constitute a signal generating means A using the DC type a1 as a signal source.

FIG. 4 shows the analog switches 3 to 3 for creating ±1.0 symbols of the output bipolar signal corresponding to the 1,0 symbols of the human-powered digital signal and outputting it from the signal transformer 9.
6 is shown.

Next, the principle of generation of an output high polar signal corresponding to an input digital signal and the output impedance at that time will be explained using FIGS. 3 and 4. First of all,
The operation of generating +1 symbol of the output bipolar signal when the symbol of the input digital signal is 1 will be explained. In this case, as shown in FIG. 4.
5 and 6 respectively OFF, ○N, OFF, OFF
A control signal is applied from the control circuit 2 so as to do this. Then, the DC power supply 1 is short-circuited through the switch 4, and at the same time, a voltage of +1 symbol [+E (volt)] is induced in the load resistor 10 having a resistance value of R (ohm) through the signal transformer 9. The output impedance in this case is O of the switch.
If the N resistance can be ignored, it is O (ohm).

The -1 symbol is also generated in accordance with the switch operation of FIG. 4 in the same manner as above.

On the other hand, when the input digital signal is an O symbol, switch 3. 4. Turn on 5 and 6 respectively.

Turn it into OFF, OFF and ON states. At this time, resistance 7. Switch 3. Since the switch 6 and the resistor 8 are connected in series, and the DC power supply 1 is connected to the midpoint of the signal transformer 9, no current flows, so the load resistor 10 has a 0 symbol [0 (volt)]. occurs. Also, the output impedance is the sum of resistors 7 and 8, that is, 4R
(ohm), but the winding ratio of the signal transformer 9 is 2:1.
Therefore, it matches the load impedance. As mentioned above, in this circuit, the output impedance when sending ±1 symbol is O (ohm), and when sending 0 symbol, it is the same as the load impedance, so the average power consumption is the so-called matching state for all symbols. This is the second case of fully matched drive. Therefore, this circuit can be called half-matched drive in correspondence with fully matched drive.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional semi-matched bipolar signal drive circuit, the DC power supply as the signal source of the bipolar signal is connected to the midpoint of the primary winding of the signal transformer, so the signal transformer cannot function as a signal transformer. Of course, it is also essential as a supply circuit for a bipolar signal source, and this signal transformer accounts for a large proportion of the cost and power consumption of the entire device. Furthermore, this signal transformer makes it extremely difficult to integrate the device into an integrated circuit, and in some cases there is a problem in that the signal transformer must be externally attached.

This invention was made to solve the above-mentioned problems, and it is possible to supply DC power as a bipolar signal source without using a signal transformer, and it is small and low-cost that realizes semi-matched drive. The objective is to obtain a bipolar signal drive circuit that is inexpensive and has low power consumption.

[Means for Solving the Problems] The bipolar signal drive circuit according to the present invention includes, in the signal generating means, an output terminal to which a load resistor is connected via a DC power supply, and the polarity thereof is switched based on the output of the control means. The device is equipped with a switch means for short-circuiting through a resistance that is equal to the load resistance value.

[Effect]

In the bipolar signal drive circuit of the present invention, the switch means is controlled by the control means based on the symbol value of the input digital signal, and the +1 symbol of the bipolar signal is applied directly to the load resistance by switching the polarity of the DC power supply. The 0 symbol is realized by not applying a DC power source to the load resistor, but by connecting a resistor whose value is equal to the load resistance value. As a result, a bipolar signal of ±1.0 symbols is created corresponding to 1.0 symbol of the human-powered digital signal, and the output impedance when transmitting ±1 symbol is 0 (ohm), and that when transmitting 0 symbol is The load impedance is the same as that of the load impedance, and this invention not only satisfies the function of a bipolar signal drive circuit but also realizes semi-matched drive without using any transformers to supply DC power as a bipolar signal source. The device will be small, low-cost, and consume even less power.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, l is the output voltage E as a bipolar signal source.
(volt) DC power supply, 12 is an analog switch using a transistor etc. 13, 14° 15, 16, 17 and 1
Control circuits 19 and 20 as control means for creating a signal for driving 8 from an input digital signal are resistors having a value of 2, which is the resistance value R (ohm) of the load resistor 10.

That is, in this embodiment, the switch means of the present application is composed of analog switches (hereinafter abbreviated as switches) 13 to 18,
A series circuit of a DC power supply 1 and a switch 13 or 16, a series circuit of a switch 14 or 17 with one end shorted, a resistor 19 or 20 having a value of 2 of the load resistance IO, and a switch 15 or 18 with one end shorted are connected in parallel. Two systems of connected circuits are provided to constitute the signal generating means A, and each output point is set as the output terminal 0 of the bipolar signal.

Therefore, in this circuit, direct type #1 as a bipolar signal source is not supplied via a signal transformer, but is directly applied to load resistor 10 via switch 13 or switch 16. Further, by short-circuiting the current flowing back from the load resistor 10 via the switch 18 or the switch 15, a bipolar signal is generated in the load resistor 10.

FIG. 2 shows the operation of the switches 13 to 18 for creating ±1.0 symbol of the output bipolar signal corresponding to 1.0 symbol of the input digital signal.

Next, the principle of bipolar signal generation and the output impedance at that time will be explained using FIGS. 1 and 2. First, the symbol of the input digital signal is 1
The operation of generating the +1 symbol of the output bipolar signal when . In this case, as shown in FIG. 2, the switches 13, 14, 15, 16, 17 and 18 are turned ON, OFF, OFF, OFF, OFF, respectively.

A control signal is applied from the control circuit 12 to turn it on.

available. Then, the DC power supply 1 is applied through the switch 13 to the load resistor 10 having a resistance value of R (ohms). The current through the load resistor lO is short-circuited by the switch 18. As a result, a +1 symbol [+E (volt)] is generated in the load resistor 10.

The output impedance in this case is O (ohm) assuming that the ON resistance of the switch can be ignored. -1 symbol is also generated according to the switch operation in Figure 2 in the same way as above, and the output impedance is 0 (ohm).
It is. On the other hand, when the input digital (No. 8 is a 0 symbol, switches 13, 14, 15, 16, 17 and 18 are turned OFF, ON, OFF, OFF, ○N, OFF, respectively.
state. At this time, the DC power supply 1 is not applied to the load resistor 10, and a 0 symbol [0 (volt)] is generated.

Further, the output impedance at that time is the sum of the resistors 19 and 20, that is, R (ohm), and is in a matching state with the load impedance.

In the above embodiment, the switch means is constructed of six analog switches 13 to 18 inserted in each circuit, but each circuit may be switched by a changeover switch or the like.

〔Effect of the invention〕

As described above, according to the present invention, based on the output of the control means, the output terminal to which the load resistance is connected to the signal generation means is connected to the DC power supply and its polarity is switched to short-circuit it, or the output terminal is connected to the load resistance value. By providing a switch means for short-circuiting through equal resistances, there is no need for any transformers to supply DC power as a bipolar signal source, resulting in a small, low-cost, and low-power bipolar signal drive circuit. There is an effect that can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
The figures are diagrams for explaining the operation of the above embodiment, FIG. 3 is a circuit diagram showing the configuration of the conventional example, and FIG. 4 is a diagram for explaining the operation of the conventional example. 1... DC power supply (signal source), 10... Load resistance, 1
2... Control circuit (control means), 13-18... Analog switch (switch means), 19.20... Resistor, A... Signal generation means, 0... Output terminal. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa (2 idiots) Figure 1
, 12 Figure 2 Figure 3 Figure 4 Procedural amendments issued on June 13th, Showa 13th.

Claims (2)

[Claims] (1) A signal generating means using a DC power source as a signal source, and a control means for controlling the signal generating means based on an input unipolar digital signal, By controlling the generating means, a multipolar bipolar signal corresponding to the above digital signal is generated at the output terminal connected to the load resistor, and the output impedance when sending ±1 symbol of the above bipolar signal is zero, 0 symbol. In the bipolar signal drive circuit in which the output impedance at the time of transmission is made equal to the load impedance, the signal generating means connects the output terminal to which the load resistor is connected via the DC power supply and the output terminal based on the output of the control means. 1. A bipolar signal drive circuit comprising a switch means for shorting by switching the polarity or shorting through a resistor equal to the load resistance value. (2) The switch means consists of an analog switch such as a transistor, and includes a series circuit of a DC power supply and an analog switch, an analog switch with one end shorted, and 1/1 of the load resistance value.
The signal generation means is constructed by providing two circuits in which a series circuit of resistors having a value of 2 and an analog switch with one end shorted are connected in parallel, and each output point is used as an output terminal for a bipolar signal. Claim 1:
The bipolar signal drive circuit described in .