JP2007013441A - Pulse generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a square wave pulse generation device for stably maintaining a duty ratio of a square wave pulse as a desired value in simple configuration. <P>SOLUTION: The comparison operation of an input signal supplied from a signal source with a threshold level L is performed by a comparing part 13 so that the rectangular wave pulse (output pulse) of a binary logic is generated corresponding to the comparison result. The duty ratio of the output pulse is detected by a threshold control part 15, and compared with a desired duty ratio by a duty ratio setting part 14 so that a duty difference signal showing a difference between the duty ratio of the output pulse and a desired duty ratio is generated, and the threshold level L is controlled to decrease the duty difference signal so that the duty ratio of the output pulse is feedback-controlled to be set as a desired duty ratio. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pulse generation device, for example, a pulse generation device that controls a duty ratio of a pulse to a desired value.

  2. Description of the Related Art Conventionally, pulse generators that generate rectangular wave pulses have been widely used in digital circuits composed of sequential circuits and combinational circuits.

  Among these pulse generators, there are also pulse generators that maintain a desired duty ratio (duty ratio: ratio of ON or OFF time to one pulse period) or pulse generators that can variably control the duty ratio. To do.

  For example, when used as a clock pulse, there is a request to maintain the duty ratio of the pulse at 50%, and for this, as disclosed in Patent Document 1, the duty ratio of a pulse with a deteriorated duty ratio is required. There is a technology to make the ratio 50%. This is a technique for setting the duty ratio to approximately 50% using, for example, a two-stage NAND gate static latch. However, in this technique, it is necessary to use a pulse with a duty ratio close to 50% as the original input pulse. The scope of application is limited.

  A combination of a sine wave oscillator and a comparator is conventionally known as a pulse generator capable of variably controlling the duty ratio (see FIG. 1). In this configuration, when the threshold level is changed, the duty ratio of the pulse changes (see FIG. 1).

JP 2001-326564 A

  However, in the conventional configuration shown in FIG. 1, in order to obtain a pulse with a desired duty ratio, for example, 50%, if the output waveform of the oscillator includes a harmonic, it is compared with the distortion waveform. The threshold value of the detector must be adjusted and set, and even if it is set, it is difficult to stably obtain a rectangular wave pulse with an accurate duty ratio of 50% due to various fluctuation factors.

  The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a pulse generator that can set a duty ratio of a rectangular wave pulse to a desired value and can be stably maintained.

  The invention according to claim 1 is a pulse generation device that converts an input signal from a signal source into a rectangular wave pulse having a desired duty ratio, and compares the input signal with a threshold value, and according to the magnitude relationship thereof. Comparing means for converting to an output pulse, duty ratio setting means for setting a desired duty ratio, and threshold control means for detecting a difference signal between the duty ratio of the output pulse and the desired duty ratio, The duty ratio of the output pulse is controlled to the desired duty ratio by feedback control of the threshold level based on the difference signal detected by the control means.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a basic block diagram showing the configuration of the pulse generation device of the present embodiment.

  In FIG. 2, the pulse generation device 10 includes a comparison unit 13, a duty ratio setting unit 14, and a threshold control unit 15, and generates a rectangular wave pulse having a desired duty ratio from an input signal.

  The comparison unit 13 compares an input signal f (t) from a signal source (not shown) with a threshold level L, converts the amplitude into a pulse having a binary logic level, and generates an output pulse.

  Here, when f (t)> L, the comparison unit 13 assumes the OFF (Low) level, and when f (t) <L, the comparison unit 13 assumes the ON (High) level. A pulse with a large ratio is generated, and a pulse with a small duty ratio is generated when the threshold level L decreases.

The duty ratio setting unit 14 holds a signal corresponding to a desired duty ratio.
The threshold control unit 15 receives the output pulse as an input, detects a comparison result (referred to as “duty difference”) between the duty ratio and the desired duty ratio, and controls the threshold level. That is, the threshold control unit 15 operates according to control logic such that the threshold level is lowered when the duty difference is positive, the threshold level is not changed when the duty difference is zero, and the threshold level is increased when the duty difference is negative. To do.

Next, the operation of the pulse generator 10 having such a configuration will be described.
A comparison operation between an input signal f (t) from a signal source (not shown) and a threshold level L is performed by the comparison unit 13, and the amplitude is converted into a binary pulse waveform corresponding to the result, and an output pulse is obtained. The duty ratio of the output pulse is detected by the threshold control unit 15 and further compared with a desired duty ratio set by the duty ratio setting unit 14, and the above control is performed in accordance with the “duty difference” signal of the comparison result. A threshold level L is generated according to the logic and supplied to the comparison unit 13.

  By configuring such negative feedback, the duty ratio of the output pulse changes to the desired duty ratio set by the duty ratio setting unit 14, and is stabilized in this state.

  When the duty ratio of the output pulse is stabilized, the threshold level output from the threshold control unit 15 becomes a constant value, and the duty ratio in that state is maintained.

  When the duty ratio of the output pulse deviates from the set value for some reason, the feedback control works on the threshold level so as to return to the duty ratio set by the same control, so that various fluctuations such as a change in the input signal waveform f (t) However, the duty ratio is kept stable.

  It should be noted that, depending on the logic of the magnitude relationship between the threshold level L and the input signal f (t) in the comparison unit 13 and the duty difference in the threshold control unit 15, the relationship between the signs of the output control amounts is reversed. Can be obtained.

  As described above, this embodiment can generate and maintain a rectangular wave pulse having a desired duty ratio by utilizing the feedback control characteristic of being resistant to various fluctuations and disturbances. The effect is demonstrated.

  Next, an embodiment will be described with reference to FIGS. FIG. 3 is a block diagram illustrating the configuration of the pulse generation device according to the present embodiment. In FIG. 3, the same or corresponding parts as those in FIG. 2 are denoted by the same reference numerals.

  In FIG. 3, the pulse generation device 10 includes a comparison unit 13, a duty ratio setting unit 14, a duty ratio detection unit 15a, a difference unit 15b, an amplifier 15c, and an integrator 15d, and a duty ratio setting unit. A pulse having a desired duty ratio set to 14 is generated.

  The comparison unit 13 compares an input signal f (t) from a signal source (not shown) with a threshold level L, converts it to an output pulse that changes at a binary amplitude level, and outputs the output pulse. Here, if the comparator 13 assumes the OFF level (VL volts) when f (t)> L, and the ON level (VH volts) when f (t) <L, the threshold level L increases. An output pulse with a large duty ratio is generated, and when the threshold level L decreases, an output pulse with a small duty ratio is generated.

  The duty ratio detection unit 15a is formed of, for example, a low-pass filter having a sufficient time constant, and outputs a DC voltage proportional to the duty ratio of the output pulse as the duty ratio detection signal Vd.

  The duty ratio setting unit 14 sets a voltage VS corresponding to a desired duty ratio. For example, the voltage VS supplied to the differentiator 15b is made variable using the divided voltage of the variable resistor.

  The differentiator 15b generates a difference between the duty ratio detection signal Vd output from the duty ratio detection unit 15a and the signal Vs corresponding to the desired duty ratio set in the duty ratio setting unit 14, that is, a “duty difference” signal. Output to amplifier 15c.

  The amplifier 15c inverts and amplifies the above-described “duty difference” signal by a predetermined factor, and outputs the amplified signal to the integrator 15d.

  The integrator 15d integrates and holds the signal from the amplifier 15c and outputs it as a threshold level L to the comparison unit 13.

Next, the operation of the pulse generator 10 having such a configuration will be described with reference to FIG.
When an input signal f (t) from a signal source (not shown) is supplied to the comparison unit 13, a comparison operation with the threshold level L is performed, and the amplitude is binary (VH, VL volts) according to the magnitude relationship of the result. It is converted into a pulse waveform and becomes an output pulse. This output pulse is input to the duty ratio detection unit 15a, and the duty ratio detection unit 15a outputs a duty ratio detection signal Vd corresponding to the duty ratio. The difference unit 15b takes a difference for comparison with the signal Vs from the duty ratio setting unit 14, the "duty difference" signal is inverted and amplified by the amplifier 15c, and further integrated by the integrator 15d to obtain a threshold level L. It is supplied to the comparison unit 13.

  Signal processing from the duty ratio detection unit 15a to the integrator 15d is processing of a control signal corresponding to the control logic in the threshold control unit 15 of the above embodiment. The differencer 15b and the amplifier 15c may be a differential amplifier configured as an integral unit.

  When the duty ratio of the output pulse deviates from the set value for some reason, feedback control operates on the threshold level L so as to return to the duty ratio set by similar control. For example, various changes such as a change in the input signal waveform f (t) It is possible to keep the duty ratio stable even with respect to fluctuations.

  As described above, this embodiment can generate and maintain a rectangular wave pulse having a desired duty ratio by utilizing the feedback control characteristic that is resistant to various fluctuations and disturbances. Demonstrate the effect.

Next, another embodiment will be described with reference to the block diagram of FIG.
The present embodiment has a configuration obtained by further developing the first embodiment.
That is, in the first embodiment, when the input signal waveform f (t) is a pulse waveform having a steep slope such as a rectangular wave, an arbitrary duty ratio is obtained by changing the threshold level L. It becomes difficult. That is, in order to obtain an output pulse having a set target duty ratio by the above operation, the input signal waveform f (t) can be obtained with an arbitrary duty ratio by changing the threshold level L. It is necessary to have a waveform like this. For example, the input signal waveform f (t) needs to be a waveform that can obtain an arbitrary duty ratio by changing the threshold level L such as a sinusoidal smooth waveform, a triangular wave, or a sawtooth wave. .

  Therefore, the present embodiment shown in FIG. 5 is made to realize a more advanced pulse generation apparatus, excluding the technical limitations in the first embodiment.

  In FIG. 5, the pulse generation device 10 of the present embodiment is based on the configuration of the first embodiment and further includes a waveform adjustment unit 16.

  The waveform adjustment unit 16 is provided at a position preceding the comparison unit 13 and adjusts a signal waveform from a signal source (not shown) to a waveform suitable for obtaining an arbitrary duty ratio by changing the threshold level L. To do.

  Further, the waveform adjusting unit 16 is formed by a band limiting filter for filtering a signal waveform from a signal source (not shown), for example. In this case, the harmonic component of the input signal f (t) from a signal source (not shown) is cut to extract the fundamental wave, and the smoothed waveform is supplied to the comparison unit 13. This makes it possible to obtain an arbitrary duty ratio by changing the threshold level L.

  The waveform adjusting unit 16 reduces the restrictions imposed on the signal from the signal source. For example, the waveform adjusting unit 16 may be a distorted waveform containing a lot of harmonics or a rectangular wave. It is possible.

  Thus, according to the present example, in addition to the effect that a rectangular wave pulse having an arbitrary stable duty ratio as described in the embodiment or the example 1 can be obtained, the waveform adjusting unit 16 is installed. As a result, the restriction that the signal waveform from the signal source must be a sine wave (or a waveform close thereto) can be relaxed, and the application range of the pulse generator can be expanded.

It is a block diagram which shows the conventional pulse generator comprised by the oscillator and the comparator. 1 is a basic configuration diagram of a pulse generation device according to an embodiment of the present invention. 1 is a block diagram of a pulse generation device according to Embodiment 1. FIG. It is explanatory drawing which shows the relationship between the duty ratio of a pulse, and a duty ratio detection signal. 6 is a block diagram of a pulse generation device according to Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pulse generator 13 ... Comparison part 14 ... Duty ratio setting part 15 ... Threshold control part 15a ... Duty ratio detection part 15b ... Difference machine 15c ... Amplifier 15d ... Integrator 16 ... Waveform adjustment part

Claims (3)

A pulse generation device that converts an input signal from a signal source into a rectangular wave pulse having a desired duty ratio,
Comparing means for comparing the input signal with a threshold value and converting it into an output pulse according to the magnitude relationship;
Duty ratio setting means for setting a desired duty ratio;
Threshold control means for detecting a difference signal between the duty ratio of the output pulse and the desired duty ratio,
A pulse generating apparatus characterized in that the duty ratio of an output pulse is controlled to the desired duty ratio by performing feedback control of the threshold level based on the difference signal detected by the threshold control means. The threshold control means includes
Duty ratio detection means for outputting a signal corresponding to the duty ratio of the output pulse;
Differential amplification means for taking a difference between an output of the duty ratio detection means and a signal at a level corresponding to a desired duty ratio set by the duty ratio setting means;
The pulse generation device according to claim 1, further comprising an integration unit that generates the threshold value by integrating an output of the differential amplification unit.   The waveform adjusting means for adjusting the waveform of the input signal from the signal source to a waveform in which a duty ratio can be arbitrarily determined according to a change in the threshold value is provided in a preceding stage of the comparing means. 2. The pulse generation device according to 2.

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