JPS584275Y2 - Waveform shaping device - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a waveform shaping device.

It is generally known to use Schmitt circuits for waveform shaping.

This utilizes the hysteresis characteristic of the Schmitt circuit. For example, when an input signal as shown in Figure 1 is given, the output rises when it exceeds the H reference level H, and the output rises when it falls below the reference level L. falls, thereby shaping the waveform of the input signal.

However, when the input signal is a modulated wave as shown in Figure 2, when attempting to shape the waveform using the Schmitt circuit as described above, hysteresis occurs for each modulated pulse, so the envelope of the modulated wave is No output is produced in the range below level H.

In other words, if there is a trough in the modulated wave that is lower than the H reference level H, the output will be interrupted during the period of this trough.

To avoid this interruption, at the output of the Schmitt circuit,
If the width of the expected trough is longer than the time T, then −L,,z
<・:, it is sufficient to prepare a monostable circuit that outputs
If the time T is set to a large value, the upper limit value of the input frequency is limited, and if the time T is set to a small value, an input signal having a valley longer than the time T cannot be shaped.

The purpose of this invention is to perform waveform shaping without interrupting the output during the trough period of the input signal when the input signal is a modulated wave.

In FIG. 3 showing an embodiment of this invention, 1 is a comparator, 2 is a retriggerable monostable circuit, 3 is a reference power source, and 4 and 5 are resistors.

The comparator 1 is supplied with a modulated wave input signal A and a reference voltage from a reference power supply 3, and outputs an output when the input signal A exceeds the reference voltage to trigger the monostable circuit 2.

In the steady state until the monostable circuit 2 is triggered and inverted, the Q output is at H level, and this is inputted to the input terminal 6 on the reference voltage side of the comparator 1 through the resistor 5 as the input B at the H reference level. A reference voltage V of 1 is given.

Note that when the monostable circuit 2 is triggered and inverted, the Q output becomes L level, and as a result, the second reference voltage v2, which is the L reference level, is applied to the input B of the input terminal 6. .

In the state where the monostable circuit 2 is not triggered, when the gold input signal A exceeds the reference voltage 2, an output pulse is output from the comparator 1, which triggers the monostable circuit 2 to invert.

Then, the Q output becomes L level for a set time t.

Note that the time t is set longer than the modulation period of the input signal.

When the Q output becomes L level, the reference voltage of the comparator 1 becomes the reference voltage (2) which is lower than the previous reference voltage (1) by a time t.

As the reference voltage becomes lower in this way, even if the pulse of the input signal becomes lower than the reference voltage V due to the trough of the modulated wave, as long as it does not become lower than the reference voltage v2,
Monostable circuit 2 each time an individual pulse of the input signal is applied
is triggered.

Each time the trigger occurs, the monostable circuit 2 again brings the Q output to the L level for a time t.

In other words, the Q output maintains the L level and continues to apply the reference voltage v2 to the comparator 1 unless the pulse of the input signal becomes lower than the reference voltage v2.

And when the pulse of the input signal becomes less than the reference voltage ■2,
When time t has elapsed since then, the monostable circuit 2 recovers from inversion and returns to a steady state, and the Q output becomes H level.

As a result of the above, the Q output of the monostable circuit 2 is a waveform-shaped output of the input signal, which is not affected by the troughs of the modulated wave.

In this case, it is only necessary to set the time t to be slightly longer than the modulation period of the input signal, so that even if the frequency of the input signal is high, the waveform can be shaped without being limited to its upper limit frequency.

As described above, according to this invention, when shaping the waveform of a modulated wave input signal, the waveform shaped output is not interrupted by the troughs of the modulated wave, and the upper limit frequency of the input signal is not limited. You can get the effect that you don't have.

[Brief explanation of drawings]

Figure 1 is a waveform shaping characteristic diagram using a Schmitt circuit, Figure 2 is a waveform shaping characteristic diagram of a modulated wave, Figure 3 is a circuit diagram showing an embodiment of this invention, and Figure 4 is a waveform diagram for explaining the operation. be. 1... Comparator, 2... Monostable circuit.

Claims (1)

[Scope of utility model registration request] a comparator that receives a modulated wave input signal and a reference voltage and outputs an output when the modulated wave input signal becomes higher than the reference voltage; and a comparator that is triggered by the output of the comparator and is longer than the modulation period of the modulated wave input signal. and a retriggerable monostable circuit that is inverted by a retriggerable value, and the output of the monostable circuit before the trigger is applied to the comparator as a first reference voltage, and the output that is inverted by being triggered is used as the first reference voltage. A waveform shaping device in which a lower second reference voltage is applied, and the output from the monostable circuit from when the monostable circuit is triggered until the monostable circuit returns to a steady state is used as a waveform shaping output.