JP2592403Y2 - Waveform shaping device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform shaping device for converting an input signal into a pulse having a predetermined duty irrespective of fluctuations in environmental temperature.

[0002]

2. Description of the Related Art A waveform shaping apparatus 1 shown in FIG. 3 is an apparatus for converting an input signal such as a clock pulse into a pulse train having a constant duty without changing a pulse cycle. The waveform shaping device 1 includes a one-shot pulse generation circuit 2 that is triggered by an edge of an input signal and generates a one-shot pulse until reset by an externally supplied reset pulse, and an output of the one-shot pulse generation circuit 2. And the threshold voltage Er given by the voltage dividing resistors Ra and Rb are compared with the integrated output of the integrating circuit 3, and the integrated output is equal to the threshold voltage E.
The reset pulse generation circuit 4 supplies a reset pulse to the one-shot pulse generation circuit 2 when r exceeds r. As the one-shot pulse generation circuit 2, a D flip-flop circuit triggered by a rising edge of an input signal is used, and can be reset by a reset pulse supplied to a clear input terminal. The integrating circuit 3 charges the capacitor C via the resistor R with the output of the one-shot pulse generating circuit 2, that is, the Q output of the D flip-flop circuit, and charges the capacitor C via the resistor R after the Q output falls. A charge / discharge circuit for discharging the battery is used. As the reset pulse generation circuit 4, a comparator is used in which an inverting input terminal is connected to a connection point between the resistor R and the capacitor C, and a connection point between the voltage dividing resistors Ra and Rb is connected to a non-inverting input terminal.

The one-shot pulse generation circuit 2 is triggered by the rising edge of a pulse of an input signal. When the Q output rises by this trigger, the integration operation by the integration circuit 3 is started, and the one-shot pulse generation circuit 2 is connected to the inverting input terminal of the reset pulse generation circuit 4. Is boosted with the terminal voltage of the capacitor C. When the terminal voltage of the capacitor C exceeds the threshold voltage Er applied to the non-inverting input terminal of the reset pulse generation circuit 4, a reset pulse is output from the reset pulse generation circuit 4 and the one-shot pulse generation circuit 2 Reset. Therefore, the pulse width T of the one-shot pulse generated by the one-shot pulse generation circuit 2 is determined by the integration time constant CR of the integration circuit 3 and the reset pulse generation circuit 4
In this case, the output duty of the one-shot pulse generation circuit 2 can be adjusted by changing the voltage dividing ratio of the voltage dividing resistors Ra and Rb. However, the one-shot pulse generation circuit 4
Is a waveform shaping device 1 for outputting the Q bar output to the outside.
Has an opposite relationship to the Q output (one-shot pulse).

[0004]

In the conventional waveform shaping device 1, the charging curve in the integrating circuit 3 is represented by an exponential function, and when the amplitude of the one-shot pulse is Vcc, the output voltage V of the integrating circuit 3 is reduced. During time t, logarithmic expression

T / CR = −ln {1- (V / Vcc)}

The following relationship is established. Therefore, when the integration time constant CR of the integration circuit 3 is 0.16 times the period τ of the input signal and the threshold voltage Er set in the reset pulse generation circuit 4 is Vcc / 2, t = τ / 2 , The output voltage V of the integrating circuit 3 reaches Vcc / 2. For this reason,
At t = τ / 2, a reset pulse is output from the reset pulse generation circuit 4 and the one-shot pulse generation circuit 2
, An output pulse having a 50% duty can be obtained.

However, if the capacitance of the capacitor C in the integrating circuit 3 increases due to a change in the environmental temperature, the charging curve of the capacitor C lays down more than before as the integration time constant CR increases. Will come. As a result, as shown by the one-dot chain line in FIG. 4C, it takes time for the terminal voltage V of the capacitor C to exceed the threshold voltage Er, and accordingly, the one-shot pulse generation circuit 2
As a result, the on-duty (the ratio of the high-level period of the pulse to one cycle) of the Q output pulse increases, so that there is a problem that the 50% duty cannot be maintained until then. When the capacitance of the capacitor C in the integrating circuit 3 is reduced, the charging curve of the capacitor C is raised more than before due to the reduction of the integration time constant CR. Has a problem that the time required for the terminal voltage V to exceed the threshold voltage Er is shortened, the on-duty of the Q output pulse of the one-shot pulse generation circuit 2 is reduced, and the 50% duty cannot be maintained. Also, Japanese Patent Application Laid-Open No. 56-04712
No. 3 “Monostable Multivibrator” has a charging conditioner.
Charging the sensor with a constant current proportional to the power supply voltage.
Power supply voltage dependency of output pulse metastable time
A monostable multivibrator adapted to be disclosed
I have. However, this does not work for the constant current circuit.
Due to the use of Tomira circuits, very complicated circuit configuration
In addition, the ambient temperature is affected by the change in the capacitance of the integrating capacitor.
Can not compensate for fluctuations in duty when
Had the problem of not being able to do so. Also, JP
Showa 55-082532 "Monostable Multivibe
The input trigger pulse has a slight
Constant so that the output pulse duty is constant.
Smoothing the output of the flow integration means with a low-pass filter,
Simple output that controls the constant current circuit with its output
A constant multivibrator is disclosed. This one is
When the output of the low-pass filter exceeds a certain reference value
Decreases the constant current value, and if it does not reach a certain reference value,
Although the current value is increased, the output of the constant current
Linear with a slope corresponding to the force voltage, that is, the constant current value
The output of a low-pass filter that smoothes the rising sawtooth voltage
The force is a quadratic or parabolic curve obtained by integrating the straight line
Change in shape. That is, multiply the voltage proportional to the constant current value.
Detected in divided form
Since the current value is variable, the voltage comparator
When compared to the case where the reference voltage is linearly variable.
The compensation operation tends to be slow, and the constant current circuit
Very complicated circuit configuration for varying the constant current value
The production cost is high.
It was.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides a one-shot which is triggered by an edge of an input signal and generates a one-shot pulse until reset by an externally supplied reset pulse. A pulse generation circuit, an integration circuit for time-integrating the output of the one-shot pulse generation circuit, a duty voltage conversion circuit for converting the output of the one-shot pulse generation circuit into a DC voltage having a negative characteristic, and a duty voltage. A reset pulse generation circuit that compares an output of the conversion circuit as a threshold voltage with an integration output of the integration circuit, and supplies a reset pulse to the one-shot pulse generation circuit when the integration output exceeds the threshold voltage. Circuit , wherein the duty voltage conversion circuit has a non-inverting input terminal.
A constant voltage that is variably set from outside is applied to
To, via said fixed resistor to the inverting input terminal Wansho Tsu DOO
A pulse is applied and the output terminal is connected to the inverted input terminal.
The feedback capacitor is connected to the one-shot pulse voltage peak value.
Divided by the resistance value of the fixed resistor
Is charged with a current having a constant current value obtained by
The on-duty of the shot pulse is multiplied by the constant current value.
DC value of the voltage value obtained by subtracting the
It is characterized by comprising an operational amplifier for outputting a voltage .

[0009]

According to the present invention, while the output one-shot pulse of the one-shot pulse generation circuit triggered by the edge of the input signal is time-integrated, the one-shot pulse is converted into a DC voltage having a negative characteristic with respect to the duty cycle of the threshold voltage. age,
By supplying a reset pulse to the one-shot pulse generation circuit when the integrated output exceeds this threshold voltage, a constant duty is always maintained even if the integrated output of the integrated circuit fluctuates due to the influence of the environmental temperature. A one-shot pulse is generated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is a circuit diagram showing an embodiment of the waveform shaping device of the present invention. FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG.

In the waveform shaping device 11 shown in FIG. 1, a duty voltage conversion circuit 12 is provided between a Q output terminal of a one-shot pulse generation circuit 2 and a reset pulse generation circuit 4, and a Q output one-time output of the one-shot pulse generation circuit 2 is provided. The configuration is such that the shot pulse is converted into a DC voltage corresponding to the duty, and is set in the reset pulse generation circuit 4 as the temperature compensation threshold voltage Etr. The duty voltage conversion circuit 12 shown in the embodiment is composed of an integration circuit using an operational amplifier 13, and voltage dividing resistors Rc and Rd for determining a reference threshold voltage Er are connected to a non-inverting input terminal of the operational amplifier 13. Connected. The inverting input terminal of the operational amplifier 13 is connected to a resistor R
It is connected to the Q output terminal of the one-shot pulse generation circuit 2 via t and at the same time to the output terminal via a feedback capacitor Ct. Further, the output terminal of the operational amplifier 13 is connected to the non-inverting input terminal of the reset pulse generating circuit 4 via the resistor Re, and is grounded via the capacitor Ce for smoothing the output voltage.

Since the non-inverting input terminal and the inverting input terminal of the operational amplifier 13 are in a virtual short (imaginary short) state, the inverting input terminal is fixed to the same reference threshold voltage Er as the non-inverting input terminal. it is conceivable that. Since the inverting input terminal can be considered to have an infinite impedance and not to flow a current, the Q output of the one-shot pulse generation circuit 2, that is, the input voltage Vcc to the operational amplifier 13
And the output voltage Etr, Er−Etr = 1 / Ct∫ (Vcc−Er) / Rt d
The relationship t is established. However, since both Vcc and Er are constant voltages that do not change with time, when the ON period of the one-shot pulse is T, the above equation can be expressed as Er-Etr = (Vcc-Er) T / CtRt. , And the output voltage Etr, Etr = Er− (Vcc−Er) T / CtRt. That is, the duty voltage conversion circuit 12
The on-period (on-duty) T of the one-shot pulse
It is obtained by multiplying the current value (Vcc-Er) / CtRt.
The value (Vcc-Er) T / CtRt is calculated from the constant voltage Er.
The voltage value obtained by the subtraction is output as Etr. Paraphrase
Then, the output voltage Etr of the duty voltage conversion circuit 12
Is subjected to a linear function correction based on the pulse width T of the Q output one-shot of the one-shot pulse generation circuit 2, in other words, the on-duty of the one-shot pulse. Therefore, if the on-duty increases, the output voltage Etr decreases. Conversely, if the on-duty decreases, the output voltage Etr decreases.
There is a relation that r increases. However, the integration time constant CtRt
Is selected to be considerably larger than the integration time constant CR of the integration circuit 3, so that the output voltage Etr of the duty voltage conversion circuit 12 can be considered to be approximately approximated by the reference threshold voltage Er.

Here, it is assumed that the capacitance of the capacitor C in the integration circuit 3 has increased due to a change in the environmental temperature. In this case, in response to the increase of the integration time constant CR of the integration circuit 3, the charging curve of the capacitor C lays down more than before, so that the terminal voltage V of the capacitor C exceeds the temperature compensation threshold voltage Etr. It will take some time before. However, the increase in the pulse width (on-time) T of the one-shot pulse also affects the temperature compensation threshold voltage Etr set in the reset pulse generation circuit 4, as shown by the dashed line in FIG. In addition, the temperature compensation threshold voltage Etr decreases according to the increased pulse width. For this reason, it is possible to avoid such a disadvantage that the reset pulse is actually output earlier and the pulse width T of the one-shot pulse is significantly increased. Conversely, it is assumed that the capacitance of the capacitor C in the integrating circuit 3 decreases due to a change in the environmental temperature. In this case, the charge curve of the capacitor C occurs higher than before due to the decrease of the integration time constant CR of the integration circuit 3, so that the terminal voltage V of the capacitor C exceeds the temperature compensation threshold voltage Etr. Time will be reduced. However, as the pulse width (on-time) T of the one-shot pulse decreases, the temperature compensation threshold voltage Etr set in the reset pulse generation circuit 4 increases. The disadvantage that the pulse width T of the shot pulse is greatly reduced can be avoided.

As described above, according to the waveform shaping device 11, the output one-shot pulse of the one-shot pulse generation circuit 2 triggered by the edge of the input signal is time-integrated, while the duty of the one-shot pulse has a negative characteristic. Converted to a DC voltage to obtain a temperature compensation threshold voltage Etr,
Since the reset pulse is supplied to the one-shot pulse generating circuit 2 when the integrated output exceeds the temperature compensation threshold voltage Etr, even if the integrated output of the integrating circuit 3 fluctuates due to the environmental temperature. Thus, a one-shot pulse having a substantially constant duty can always be generated.

The output duty is changed by changing the voltage dividing ratio by the voltage dividing resistors Rc and Rd in the duty voltage conversion circuit 12 and variably setting the reference threshold voltage Er.

[0016]

As described above, this invention time-integrates the output one-shot pulse of the one-shot pulse generation circuit triggered by the edge of the input signal,
Because the duty voltage of the one-shot pulse is converted into a DC voltage having a negative characteristic to be a threshold voltage, and a reset pulse is supplied to the one-shot pulse generation circuit when the integrated output exceeds the threshold voltage. When the output curve along the time lapse of the integrating circuit becomes more horizontal than before due to the influence of the environmental temperature, the threshold set in the reset pulse generating circuit due to an increase in the on-duty of the one-shot pulse. Since the value voltage is temperature compensated higher than before, the reset pulse is actually output earlier than if left without temperature compensation, and the inconvenience of greatly increasing the on-time of the one-shot pulse is avoided. If the output curve along the time course of the integrator circuit is higher than before due to the environmental temperature, Since the threshold voltage set in the reset pulse generation circuit is compensated for the temperature lower than before due to the decrease of the on-duty of the reset pulse, the reset pulse is actually delayed later than when left without temperature compensation. is output, the on-time of the one-shot pulse can avoid inconvenience greatly reduced, thereby it is possible to accurately convert the pulse duty which is determined the input signal regardless of variations in ambient temperature and De
Duty voltage conversion circuit can be externally connected to the non-inverting input terminal.
When a constant voltage is applied,
Apply the one-shot pulse to the terminal via a fixed resistor
Feedback capacitor that connects the output terminal and the inverting input terminal.
The voltage of the one-shot pulse and the constant voltage
Constant obtained by dividing the difference from the pressure by the resistance value of the fixed resistor.
Charging with a current having a current value, the one-shot pulse
The value obtained by multiplying the constant current value by the on-duty of
Outputs the DC voltage of the voltage value obtained by subtracting from the constant voltage.
Output terminal and inverted input
Terminal using an operational amplifier connected with a feedback capacitor.
A current-type duty-voltage conversion can be configured.
The duty-voltage conversion circuit has a simple circuit configuration
And the output of the operational amplifier itself is
Linear compensation for on-duty of on-shot pulse
Since it is, of the capacitor generated due to the environmental temperature, etc.
Obtain pulses without duty fluctuation in response to capacitance changes
It exhibits an excellent effect such that Ru can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a waveform shaping device according to the present invention.

FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG.

FIG. 3 is a circuit diagram illustrating an example of a conventional waveform shaping device.

4 is a signal waveform diagram of each section of the circuit shown in FIG.

[Explanation of symbols]

 Reference Signs List 2 one-shot pulse generation circuit 3 integration circuit 4 reset pulse generation circuit 11 waveform shaping device 12 duty voltage conversion circuit 13 operational amplifier Ct feedback capacitor

Claims (1)

(57) [Scope of request for utility model registration] 1. A one-shot pulse generation circuit for generating a one-shot pulse triggered by an edge of an input signal until reset by an externally supplied reset pulse, and time-integrating the output of the one-shot pulse generation circuit An integration circuit, a duty voltage conversion circuit for converting the output of the one-shot pulse generation circuit into a DC voltage having a negative characteristic, and an integration output of the integration circuit with the output of the duty voltage conversion circuit as a threshold voltage. A reset pulse generating circuit for supplying a reset pulse to the one-shot pulse generating circuit when the integrated output exceeds the threshold voltage ,
The duty voltage conversion circuit is connected to a non-inverting input terminal
A constant voltage that is variably set from
The one-shot pulse via a fixed resistor
Is applied and the feedback terminal connects the output terminal and the inverting input terminal.
The capacitor is connected to the one-shot pulse voltage peak value and
It is obtained by dividing the difference from the constant voltage by the resistance value of the fixed resistor.
Charge with a current having a constant current value
The value obtained by multiplying the pulse on-duty by the constant current value is
DC voltage of a voltage value obtained by subtracting from the constant voltage
A waveform shaping device comprising an operational amplifier for outputting .