JPS6277715A - Waveform shaping circuit - Google Patents

Abstract

PURPOSE:To facilitate the waveform shaping by branching a part of an input signal, retarding it by a delay circuit and using an output compressed by a fixed level provision circuit depending on the waveform as a comparison reference of a comparator. CONSTITUTION:A signal given from an input terminal 1 is branched by a branch point 10, a peak value is divided by a voltage division circuit 11, the level is decreased and retarded by a delay circuit 12. The signal is fed to the fixed level provision circuit 6 via a buffer 5 to form a compressed signal. The signal is fed to the comparator 8 as a comparison reference level. Thus, when the signal level is increased with respect to the reference level, the signal is set and an output waveform rises and turned off when decreased conversely and the output waveform descends. Thus, the waveform shaping is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a waveform shaping circuit for a digital data transmission circuit.

(Prior art and its problems) Conventionally, many of these waveform shaping circuits hold the peak value of a signal, add it to a comparator based on a level of % of this hold value, and when the level is above this level, it is 1, and less than 1. Then let it be determined as 0.

As an example of such a conventional peak value hold type circuit, for example, the one shown in FIG. 4 is known.

In this case, one of the signals from the input terminal 31 is directly input to the child terminal of the comparator 38 , and the branch signal from the branch point 40 is peak-held by the capacitor 34 . The held peak value is passed through a buffer 35 with a gain of 1,
Comparator 38 as two levels by volume 36
The reference value is inputted to one terminal of , and is compared with the direct input signal and outputted to the output terminal 39 .

A disadvantage of this method is that it is difficult to determine the peak hold time constant. That is, in such a circuit, capacitor 34.
It is difficult to set the specific number of peak holds by the resistor 33 to a value that properly corresponds to the input signal, and in reality, the signal transmission is not carried out accurately, and if the time constant is too long, it will not follow sudden changes in the signal level. If it is not possible and it is too short, the role of the reference level as an intermediate value between the peak and the bottom will be lost.

(Means for Solving the Problems) An object of the present invention is to solve the above problems and provide a circuit that performs waveform shaping without peak holding.

That is, a delay circuit is provided to delay an input signal, and the output of this delay circuit is used as a comparison reference for the comparator.

Furthermore, a fixed level applying circuit is also provided which compresses the output of the delay circuit according to the waveform, and the output of this fixed level applying circuit is used as a comparison standard for the comparator.

(Function) Since the input signal is delayed or further compressed and used as a comparison signal without using a peak hold value that is difficult to set as in the case of two series, the input signal level increases with respect to this reference signal level. By turning on when the signal is on and turning off when the signal is decreasing, it is possible to reliably obtain a rectangular wave corresponding to the input signal even if the input signal is considerably distorted.

(Example) FIG. 1 is a block diagram of a circuit v8 according to an embodiment of the present invention.

The signal input from input terminal 1 is branched at branch point 10, the peak value is divided and leveled down by voltage divider circuit 11 composed of resistors 2 and 3, and voltage divider circuit 11 composed of resistors 2 and 3 and ml capacitor 4 is used. The signal is delayed by a delay circuit 12. This signal is passed through a buffer 5 with a gain of 1, a fixed level on the bottom side is given to a fixed level giving circuit, and is supplied to a comparator 8 as a comparison reference level L7, and is outputted as a waveform-shaped output waveform to an output terminal 9. .

According to the circuit configuration of the present invention, a part of the signal entering the first comparator 8 is branched and inputted to the delay circuit 12 composed of C3R, and the output of the delay circuit 1t'812 is set to the reference level. Therefore, when the signal level increases with respect to the reference level, it turns on and the output waveform rises, and when it decreases, it turns off and the output waveform falls.

The characteristic structure of the present invention is in this part.Actually, there may be a flat part of the peak level (saturated state) and a flat part of the bottom level (standard state! f3), but in this case, 1
On the peak side, the reference level is lowered by the resistance ratio, or by loss in the delay circuit. Furthermore, by adding a fixed level to the bottom side with the reference state being a level slightly higher than the 0 level, it becomes possible to shape the waveform of any input waveform.

FIG. 2 shows the relationship of signal waveforms indicating the operation of each part of the circuit. The input signal 21 [FIG. 2 (a)] of the input terminal 1 ((point a1) in FIG. Figure (b
)]. The peak value of this waveform 22 is leveled down by the voltage divider circuit 1 consisting of resistors 2.3, and is slightly lower than the peak value of the input signal waveform 21 (dashed line) as shown in FIG. This delayed signal is set to a fixed level of a reference state slightly higher than the input signal waveform 21 (broken line) 00 level as shown in FIG. The bottom side is set, and as a result, the input signal is given to the comparator 8 as a comparison reference signal waveform 23 (FIG. 1 (point C1)) with a compressed feel.

Therefore, at the output terminal 9 [point ID1 in Figure 1], there is a rectangular wave 24 [that rises when the input signal waveform 21 crosses the comparison reference signal waveform 23 from below, and similarly falls when it crosses -1 from the other side]. FIG. 2(d)] is output.

According to the present invention, the above-described compression operation is not necessarily necessary when shaping an input signal having a waveform without a saturation value, such as a sine wave or a triangular wave. FIG. 3 shows the above-mentioned state, and shows the case of a sine wave.

(Effects of the Invention) As described above, even if the digitalized rectangular wave is deformed into a triangular wave or a sine wave, the change can be captured and reshaped stably and reliably. In addition, even if the waveform is partially distorted, the part where the increasing trend has become dull is O
N. Since the portion where the decreasing trend has stopped is turned off, waveform shaping can be easily performed in any case.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram of an embodiment of the present invention, Fig. 2 is a signal waveform diagram of each part, Fig. 3 is a signal waveform diagram when a sine wave is used in the case of the present invention, and Fig. 4 is a conventional circuit configuration. It is a diagram. 6: Fixed level giving circuit, 8: Comparator.

Claims (1)

[Claims] 1) A waveform shaping circuit that uses a comparator to perform waveform shaping, characterized in that a delay circuit that delays an input signal is provided, and the output of this delay circuit is used as a comparison reference for the comparator. circuit. 2) In a circuit that performs waveform shaping using a comparator, a delay circuit that delays an input signal and a fixed level imparting circuit that compresses the output of this delay circuit are provided,
A waveform shaping circuit characterized in that the output of the fixed level imparting circuit is used as a comparison standard for the comparator.