JPS5850452B2 - pulse shaping circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse shaping circuit for shaping an input pulse signal to obtain a trigger pulse signal synchronized with the input pulse signal.

Conventionally, as a circuit for obtaining a trigger pulse for triggering a multivibrator circuit or the like, there has been a differentiator circuit 3 consisting of a capacitor C1 and a resistor R1, as shown in FIG.

That is, when an input pulse signal as shown in FIG. 2A is applied to the input terminal 1, a differentiated output pulse signal as shown in FIG. 2B is taken out from the output terminal 2 at its rising and falling edges. , this output pulse signal is used as a trigger pulse.

However, the conventional circuit described above has the disadvantage that when trying to obtain a trigger pulse with a small pulse width, a sufficient amplitude cannot be obtained, and when trying to obtain a trigger pulse with a large amplitude, the pulse width cannot be reduced.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a pulse shaping circuit that can obtain a trigger pulse with a small pulse width and sufficient amplitude, and is not affected by fluctuations in power supply voltage.

The configuration and operation of the present invention will be explained below based on the drawings.

FIG. 3 is a circuit diagram showing an embodiment of the pulse shaping circuit of the present invention.

In the figure, 4 is a differential amplifier composed of transistors Q and Q2, and the base of transistor Q1 is connected to input terminal 1 via capacitor C2, and is also connected in series to first power supply element B. Resistors R2 and R3
via a resistor R4, the emitter is connected to a constant current source S1, and the collector is connected via a resistor R5 to a second
The base of the transistor Q2 is connected to the connection point of the resistors R2 and R3 through the resistor R6, the emitter is connected to the constant current source SI, and the collector is connected to the first power source B2 through the resistor R7. is connected to the power supply element B1.

The power supply voltage vBl of the first power supply element B1 is the same as that of the second power supply element B2.
The power supply voltage vB2 is set to a value higher than the power supply voltage vB2.

A capacitor C3 is connected between the collector of the transistor Q2 and the ground, and the capacitor C3 and the resistor R7 constitute an integrating circuit 5.

6 is a logic circuit that performs an AND operation, and includes diodes D,...
It consists of D2 and resistor 8.

Reference numeral 7 denotes a voltage comparator circuit, which is composed of a differential amplifier made up of transistors Q3 and Q4.

The base of transistor Q3 is connected to each diode D1. It is connected to the collectors of transistors Ql and Q2 via D2, and to the second power supply element 82 via a resistor R8, its emitter is connected to constant current source S2, and its collector is connected to second power supply element B2. directly connected, transistor Q
The base of 4 is a resistor R connected in series to the second power supply element B2.
0 and Rlo, its emitter is connected to a constant current source S2, and its collector is connected to the second power supply element B2 via a resistor R1□ and to the output terminal 2.

In such a configuration, when an input pulse signal as shown in FIG. 4A is applied to the input terminal 1, when the human input pulse signal is at a high level, the transistor Q is turned on.
Transistor Q2 is turned off, and when the level is low, transistor Q1 is turned off, transistor Q2 is turned on, and transistor Q is turned off.

An output pulse signal as shown as the 8 curve (represented by a dotted line) in FIG. 4B is obtained from the collector of the transistor Q.
An output pulse signal having an opposite phase to the collector output of the transistor Q1 is obtained at the collector of the transistor Q1.

The output pulse signal from the collector of the transistor Q2 is integrated by the capacitor C3 of the integrating circuit 5, and the output pulse signal is integrated by the capacitor C3 of the integrating circuit 5.
Output signals shown as six curves (represented by dashed lines) are obtained.

The collector output of the transistor Q1 and the output of the integrating circuit 5 are applied to diodes D, D2, respectively, and a logical product is performed.
A logic output is obtained, shown as curve C (represented by a solid line) in Figure B.

When the level of this logic output is lower than the threshold level of the voltage comparison circuit γ determined by transistor Q4, resistors R9 and R[0, transistor Q3 is turned off and transistor Q4 is turned on, and the level of the logic output is set to the above threshold level. When higher, transistor Q3 is on,
Transistor Q4 is turned off, and the fourth
An output pulse signal whose waveform has been shaped as shown in FIG. C is obtained.

Therefore, the output pulse signal obtained at the output terminal 2 is synchronized with the input pulse signal and has been shaped to have a small pulse width, and is a pulse signal suitable for use as a trigger pulse signal.

In this case, the power supply that determines the threshold level of the voltage comparator circuit 7 is the same power supply terminal B2 as the power supply that determines the reference level (...I level) of the logic output, so even if the power supply voltage fluctuates, The logic output always crosses the threshold level, and the trigger pulse at the output terminal can be stably obtained without being affected by power supply voltage fluctuations.

Note that in the differential amplifier 4, the power supply voltage of the first power supply element B applied to the transistor Q2 connected to the integrating circuit 5 is set higher than the power supply voltage of the second power supply element B2 applied to the transistor QL. , transistor Q1
The amplitude of the output pulse signal obtained from the collector can be selected to be small, and radiation can be prevented.

FIG. 5 is a circuit diagram showing another embodiment of the pulse shaping circuit of the present invention.

In FIG. 5, the second power supply voltage in FIG. 4 is generated from the first power supply element B4 via a constant voltage circuit composed of a resistor R12t R+3 and a transistor Q5.

Further, the constant current source S is composed of resistors R, 4, R, 5, R16 and a transistor Q6, and the constant current source S2 is composed of a resistor R1.
75R18) R1, and a transistor Q7.

Further, a diode D3 is connected between the emitter of the transistor Q5 and the base of the transistor Q4 to determine the threshold level of the voltage comparator circuit 1.

In this case, if the amplitude of the output pulse signal obtained from the collector of transistor Ql is selected to be approximately twice or more the forward voltage drop of diode D3, the waveform shaping operation can be performed extremely stably.

As described above, according to the present invention, a stable trigger pulse signal that is not affected by changes in the power supply voltage can be generated with a simple configuration, and the pulse width of the trigger pulse can be made sufficiently small, and a sufficient amplitude can be obtained.

Furthermore, the pulse shaping circuit of the present invention is easy to integrate.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional pulse shaping circuit, FIG. 2 is a pulse waveform diagram explaining the operation in FIG. 1, FIG. 3 is a circuit diagram showing an embodiment of the pulse shaping circuit of the present invention, and FIG. This figure is a pulse waveform diagram for explaining the operation in FIG. 3, and FIG. 5 is a circuit diagram showing another embodiment of the pulse shaping circuit of the present invention. 1...Input terminal, 2...Output terminal, 4
... Differential amplifier, 5 ... Integrating circuit, 6 ... Logical operation circuit, 7 ... Voltage comparison circuit.

Claims (1)

[Claims] 1 a first power supply, a second power supply having a power supply voltage lower than the power supply voltage of the first power supply, and a second power supply to which an input pulse signal is applied to the input terminal and connected to the first and second power supplies, respectively. a differential amplifier from which output pulse signals of mutually opposite phases are taken out at two output terminals; an integrating circuit connected to the output terminal of the differential amplifier connected to the first power supply; and an output of the integrating circuit. a logic circuit that performs a logical operation between the signal and the output pulse signal from the output terminal of the differential amplifier connected to the second power supply; and a logic circuit that sets the logic output of the logic circuit to a set threshold level. A voltage comparator circuit that compares and shapes waveforms, and a power supply circuit that commonly supplies a voltage for setting a threshold level of the voltage comparator circuit and a reference level of the logic output from the logic circuit. A pulse shaping circuit characterized in that a trigger pulse signal obtained by shaping the input pulse signal is obtained as an output of a comparison circuit.