JPH0595260A - Voltage amplifier circuit - Google Patents

Abstract

PURPOSE:To attain communication without error even when noise and waveform distortion take place in a transmission line by using a voltage amplifier circuit comprising two transistors(TRs), two capacitors, four diodes and four resistors so as to amplify and output a pulse signal. CONSTITUTION:With a pulse signal at a point (c) set to +5V, a C2 is charged by a path comprising a TR 3, the capacitor(C)2 and a diode 4 and the potential of the C1 changes from +5V to +10V. Then the capacitor C1 is discharged via a resistor R6 to turn on a TR 5 and a point (f) reaches a pulse signal output of +10V. With a pulse signal at the point (c) set to 0V, the C1 is charged through a path comprising a diode 1, the C1 and the TR 4, the positive pole of the C2 connects to ground via the TR 4 and the negative pole of the C2 reaches -5V. Moreover, the TR 6 is turned on by a current through the C2 via a resistor R9, the TR 6 and a resistor R7, the point (f) reaches -5V, that is, the signal is amplified from 5V into 15V in terms of a peak level and the result is outputted. Thus, even when noise or waveform distortion takes place in the transmission line, communication is attained without an error.

Description

Detailed Description of the Invention

[0001]

3. The voltage amplifier circuit according to claim 1, wherein the first transistor is a PNP transistor, and the second transistor is an NPN transistor.

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage amplifier circuit for amplifying and outputting a voltage of an input pulse signal.

[0003]

2. Description of the Related Art Data communication for transmitting data from a data terminal device such as a personal computer through a transmission line such as a communication line is widely used. In such a case, the output circuit that sends data as a pulse signal to the transmission line sends a small signal pulse signal obtained from a device centered on the microprocessor in the data terminal device to the transmission line after current amplification. To do. FIG. 3 shows a conventional output circuit, which includes a transistor T
This is a so-called complementary two-stage amplifier circuit composed of R1 to TR4 and resistors R1 to R5. Since + 5V is supplied to the power supply and the resistors R2 and R3 have the same resistance value, the resistors R2 and R3
3 connection point, that is, transistors TR1 and TR2
The emitter of is biased at + 2.5V. Therefore, when the signal input is higher than + 2.5V, the transistors TR1 and TR3 are turned on, a current-amplified signal output of + 5V is obtained at the output, and the source current is sent to the transmission path. When the signal input is lower than + 2.5V, the transistors TR2 and TR4 are turned on, the output signal becomes 0V, and the sink current from the transmission line is drawn. As described above, the data is sent to the transmission line having a low impedance, that is, a heavy load, such as a communication line after the current amplification.

[0004]

However, when the transmission line is long, the distortion of the received waveform is large on the receiving side that receives the data due to the influence of external noise and the capacitive component and the inductive component of the transmission line. Communication errors are likely to occur, and it is necessary to amplify the voltage when transmitting a signal.
Therefore, use a separate power source to amplify the voltage, or
It required a booster circuit such as a switching regulator. However, preparing a separate power supply or booster circuit for the output circuit has a problem in terms of cost, and further, when a switching regulator is used, it causes high frequency noise, which is a problem.

The present invention solves the above-mentioned conventional problems, and provides a voltage amplifier circuit with a simple circuit configuration that eliminates an error in data communication even when the distortion of the received waveform becomes large on the receiving side. The purpose is to

[0006]

In order to achieve the above object, the present invention comprises two transistors, four diodes,
A simple circuit configuration with four resistors and two capacitors is used.

[0007]

With the above structure, the voltage amplifying circuit according to the present invention amplifies the pulse voltage of the input signal and outputs the tripled pulse voltage without requiring a separate power supply.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a circuit in which the conventional output circuit of FIG. 3 is used as a front stage and a voltage amplifier circuit of the present invention is added in a rear stage thereof. The same components as those of FIG. The added circuit at the subsequent stage will be described.

In FIG. 1, transistors TR3 and T3
To the collector of R4, the conventional output terminal, there are first and second diodes D2, D3 connected to the anode and cathode, respectively, and first and second capacitors C1, C2 connected to the negative and positive electrodes, respectively. is there. The cathode is connected to the cathode of the diode D2,
There is a third diode D1 whose anode is connected to a + 5V power source, and a fourth diode D4 whose anode is connected to the anode of the diode D3 and whose cathode is grounded.

The cathodes of the diodes D1 and D2 and the positive electrode of the capacitor C1 are connected via the first resistor R1 to the first PNP transistor T.
It is connected to the emitter of R5, the anodes of the diodes D3 and D4 and the negative electrode of the capacitor C2 are
Through the resistor R7, which is the second transistor N
It is connected to the emitter of the PN transistor TR6.

The base of the transistor TR5 is connected to a + 5V power source through a third resistor R8.
In addition, the base of the transistor TR6 is connected to the ground via the fourth resistor R9. Transistor T
The collectors of R5 and TR6 are connected to each other and to the output terminal.

Next, the operation of the circuit having the above configuration will be described with reference to FIGS. 2 (a) to 2 (f). In FIG. 1, when the pulse signal at the point c is + 5V, a closed circuit is formed by the transistor TR3, the capacitor C2 and the diode D4, a current flows, and the capacitor C2 is instantly charged. Then, the potential of the capacitor C1 charged to + 5V is shifted by 5V to + 10V, and the electric charge charged to the capacitor C1 is discharged, so that the base current flows through the transistor TR5 via the resistor R6, and the transistor TR5 is discharged. When turned on, a pulse signal of +10 V is obtained at the output terminal f.

On the other hand, when the pulse signal at the point c is 0 V, a closed circuit is formed by the diode D1, the capacitor C1 and the transistor TR4, a current flows, and the capacitor C1 is instantly charged. Furthermore, the capacitor C2
Since the positive electrode of the capacitor C2 is grounded by the transistor TR4, the negative electrode of the capacitor C2 becomes -5V, a current flows from the ground to the capacitor C2 via the resistor R9, the transistor TR6 and the resistor R7, and the transistor TR6 is turned on. Therefore, the voltage of the output terminal f becomes -5V.

When the pulse signal shown in FIG. 2 (a) is supplied to the point a which is the input terminal, as described in the conventional example, b
The signal waveforms at the points and the points c are as shown in FIGS. Although the waveform at the point a and the waveform at the point c are apparently the same, as described above, the pulse signal at the point c is current-amplified. The waveforms of the pulse signals at the points d, e, and f are as shown in FIGS. 2D, 2E, and 2F. That is, when a pulse signal with a peak value of 5V shown in FIG. 2C is input to the circuit of the subsequent stage according to the present invention, a pulse signal with a peak value of 15V tripled as shown in FIG. 2F is obtained. It will be.

In the above embodiment, the power supply voltage supplied to the circuit in the subsequent stage is +5 V, but it may be a voltage of another value, and if the supplied power supply voltage is E, 3E is output to the output terminal f. A pulse signal with a peak value will be obtained.

Further, since it is a very simple circuit, cost reduction can be achieved and it is possible to realize an IC (integrated circuit).

[0017]

As described above, in the voltage amplifying circuit according to the present invention, the input pulse signal of the pulse signal can be changed by a very simple circuit configuration without the need of a booster circuit such as a separate power source or a switching regulator. Since the voltage can be amplified to 3 times the voltage and output, a signal with few errors on the receiving side can be received regardless of the influence of noise mixed in the transmission line and the occurrence of waveform distortion due to the characteristics of the transmission line. There is an effect that you can.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of an output circuit using a voltage amplifier circuit according to the present invention.

2A to 2F are waveform diagrams of signals at points a to f in the circuit of FIG.

FIG. 3 is a circuit diagram of a conventional output circuit.

[Explanation of symbols]

 C1, C2 capacitors D1, D2, D3, D4 diodes R1 to R9 resistors TR1 to TR6 transistors

Claims (2)

[Claims] 1. A first diode having an anode connected to an input terminal, a second diode having a cathode connected to the input terminal, and a first capacitor having a negative electrode connected to the input terminal, A second capacitor having a positive electrode connected to the input terminal; a third capacitor having a cathode connected to the cathode of the first diode and the positive electrode of the first capacitor; and an anode connected to the first potential. A diode; a fourth diode having an anode connected to the anode of the second diode and a negative electrode of the second capacitor, and a cathode connected to a second potential lower than the first potential; A first resistor whose one end is connected to the cathode of the diode, and a second resistor whose one end is connected to the anode of the fourth diode; A first and a second transistor having respective emitter electrodes connected to the other ends of the resistors, and one end connected to the base electrode of the first transistor and the other end connected to the first potential. A third resistor, a fourth resistor whose one end is connected to the base electrode of the second transistor and the other end of which is connected to the second potential, and both of the first and second transistors. A voltage amplifying circuit having an output terminal connected to a collector electrode. 2. The voltage amplifier circuit according to claim 1, wherein the first potential and the second potential are a positive potential and a ground potential, respectively.