JPH0743398B2 - Section length measurement circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a section length measuring circuit for measuring a section length of a signal that is equal to or more than a predetermined value by using a voltage comparator.

(Prior Art) A conventional section length measuring circuit, for example, as shown in FIG. 3, outputs a high potential output (this is referred to as a positive polarity side output) and a positive polarity side output when a signal input is equal to or higher than a reference voltage. voltage comparator outputs the this referred to as negative-side output) 1, a start gate 2 made of E _X -OR gate for receiving the positive polarity side output and T _ON / T _OFF voltage from voltage comparator 1 , E _X to enter the negative polarity side output and T _ON / T _OFF voltage from the voltage comparator 1
-A stop gate 3 consisting of an OR gate, an inverter 4 for inverting the output of the start gate 2 and a NAND gate 5 for receiving the output of the inverter 4 and the output of the start gate 2 as inputs, and using the delay in the inverter 4 to start a predetermined width It comprises a start trigger pulse generator 6 for generating a pulse, an inverter 7 for inverting the output of the stop gate 3 and an output of the inverter 7 and a NAND gate 8 for receiving the output of the stop gate 3 as input. 1 is provided with a stop trigger pulse generator 9. For example, the counting of high frequency pulses is started by the fall of the output from the start trigger pulse generator 6, the above counting is stopped by the fall of the output from the stop trigger pulse generator 9, and the voltage comparison is performed by this count value. The section length in which the measured input signal level applied to the (+) side input terminal of the device 1 is equal to or higher than the reference voltage is measured. Also, the section length of the measured input signal level below the reference voltage is measured by changing the polarity of the T _ON / T _OFF voltage.

(Problems to be Solved by the Invention) In the conventional example as described above, there is a problem that an error occurs in the section length measurement of the input signal to be measured due to the temperature characteristic that the edge of the output of the voltage comparator inclines with temperature. Atsuta

An example of a voltage comparator whose output edge slopes with temperature is
For example, National Semiconductor LM162 / LM161 / LM
It is just like that seen in 361. In these examples, the standard value is specified as 14 ns and 20 ns at an ambient temperature of 25 ° C, and it has been published as a characteristic diagram that this propagation delay time increases with increasing ambient temperature. As described above, the error occurs in the measurement of the section length due to the temperature characteristics when the above is used. Further, when the output stage is an open collector output, the rise is slow, and this delay is determined by the time constant of the resistor and the capacitor connected to the transistor of the output stage. Furthermore, this time constant changes with temperature. Therefore, when the output stage has an open collector configuration, the output edge is inclined depending on the temperature. As described above, an error occurs in the section length measurement due to the temperature characteristics even when the output stage uses a voltage comparator having an open collector configuration.

In the above-mentioned conventional example, a signal input a as shown in FIG. 4 (a) is applied to the input terminal 10, a reference voltage b as shown in FIG. 4 (a) is applied to the input terminal 11, and a T input is applied to the input terminal 12. _ON / T _OFF
A voltage is applied. Now, it is assumed that the section length in which the measured voltage is equal to or higher than the reference voltage is measured. In this case, a low potential is selected as the T _ON / T _OFF voltage.

By applying the signal input a and the reference voltage b, the output of the positive polarity side output terminal OUT1 of the voltage comparator 1 has the waveform shown in FIG. 4 (b), and the negative polarity side output terminal OUT2 of FIG. 4 (c). The waveform output shown in is generated. Due to this output, a negative pulse as shown in FIG. 4 (d) is generated from the start trigger pulse generator 6, and a negative pulse as shown in FIG. 4 (e) is generated from the stop trigger pulse generator 9. A pulse is generated.
The pulse widths of the pulses shown in FIGS. 4D and 4E are related to the delay time of the inverter 4 and the delay time of the inverter 7. When measuring the section length less than the reference voltage, set the T _ON / T _OFF voltage to high potential.

However, when the output of the voltage comparator 1 has temperature characteristics such that the output rises due to the ambient temperature at the rise of the output as shown by the broken line (or the alternate long and short dash line) in FIGS. Due to the characteristics, the fluctuations shown by the broken line (or the alternate long and short dash line) occur at the fall timing of the output from the start trigger pulse generator 6 and the fall timing of the output from the stop trigger pulse generator 9. Here, in FIGS. 4 (b) to (e), the broken line corresponds to the broken line, and the alternate long and short dash line corresponds to the alternate long and short dash line. As a result, there is a problem that an error occurs in the cycle measurement, as described above.

It is an object of the present invention to provide a section length measuring circuit that solves the above problems.

(Means for Solving Problems) The present invention has the following structure in order to solve the above problems.

A section length measuring circuit for measuring a section length in which the signal input level is equal to or higher than the reference voltage or a signal input level is less than the reference voltage, and a voltage comparator for comparing the signal input level with the reference voltage, First and second trigger pulse generators that output a pulse of a predetermined width from the edge of the input signal;
One that has the positive and negative output of the voltage comparator as the input and does not have the temperature characteristic of the output of the voltage comparator from the output related to the input by the selection signal related to the type of measurement section length And a data selector which supplies the first and second trigger pulse generators to the edge side of.

(Operation) In the present invention configured as described above, the positive side output and the negative side output of the voltage comparator are supplied to the data selector, and the positive side is output by the selection signal related to the type of the measurement section length. From the output related to the output and the output related to the negative polarity side, the edge side of the output of the voltage comparator which does not have the temperature characteristic is supplied to the first and second trigger pulse generators and released from the temperature characteristic. .

More specifically, for example, when the rising edge of the output of the voltage comparator has a temperature characteristic in which the rising edge is inclined, the data selector inverts the positive polarity side output and the negative polarity side output in the first output. When the section length is measured, it is supplied to the second trigger pulse generator and the first trigger pulse generator separately, so that the output of the voltage comparator on the side not having the temperature characteristic is the first and the second. It is possible to accurately measure the first section length regardless of the temperature change due to the trigger pulse generator being triggered. Further, in the case of measuring the second section length, the output from the data selector, which is the output on the positive polarity side inverted by the data selector, is
By supplying the output from the data selector, which has inverted the output on the negative polarity side, to the second trigger pulse generator, the output of the voltage comparator on the side having no temperature characteristic As the 1st and 2nd trigger pulse generators are triggered, the second section length can be accurately measured regardless of the temperature change.

When the output edge of the output of the voltage comparator has a temperature characteristic in which the falling edge is inclined, it is sufficient to use a data selector that outputs the input without inverting it.

It should be noted that the more detailed operation will be further clarified by the embodiment.

(Examples) Hereinafter, the present invention will be described with reference to Examples.

FIG. 1 is a block diagram showing the construction of an embodiment of the present invention.

In one embodiment of the present invention, the same components as those of the conventional example shown in FIG. 3 are designated by the same reference numerals.

The positive side output of the voltage comparator 1 is supplied to the input terminals 1B and 2A of the data selector 10, the negative side output is supplied to the input terminals 1A and 2B of the data selector 10, and the T _ON / T _OFF voltage is supplied to the data selector 10. It is supplied as a selection signal.

The output terminal ▲ ▼ of the selector 10 is supplied to the start trigger pulse generator 6, the output terminal ▲ ▼ is supplied to the stop trigger pulse generator 9, and they are applied to the output terminals 13 and 14, respectively.

The operation of the embodiment of the present invention configured as described above will be described.

In the voltage comparator 1, the signal input a applied to the input terminal 10 and the reference voltage b applied to the input terminal 11 are compared. Output from output terminal OUT1 of voltage comparator 1 and output terminal
There is a relationship between the output from OUT2 and the output of output terminal OUT1 that is the inverted output of output terminal ▲ ▼, and the voltage is different from the signal input a and reference voltage b shown in Fig. 2 (a). The output from the output terminal OUT1 of the comparator 1 has a waveform as shown in FIG. 2 (b), and the output from the output terminal (1) has a waveform as shown in FIG. 2 (c). Here, in FIGS. 2B and 2C, the solid line shows an ideal case where there is no output inclination due to the temperature characteristic, and the broken line portion shows the waveform portion when there is a rising inclination due to the temperature characteristic. . The same applies to FIGS. 2D and 2E described later.

The data selector 10 selects the output from the output terminal OUT1, ▲ ▼ of the voltage comparator 1 according to the level of the T _ON / T _OFF signal, and outputs the output terminal ▲ ▼, ▲ of the data selector 10.
Output to ▼ respectively. For example, when the T _ON / T _OFF signal has a low potential, the "A" side on the input side is selected, and when the T _ON / T _OFF signal has a high potential, the "B" side on the input side is selected. Now
When the T _ON / T _OFF signal is set to a high potential, the input of the input terminal 2B is output to the output terminal ▲ ▼ of the data selector 10 and the input of the input terminal 1B is output to the output terminal ▲ ▼ after being inverted. Therefore, the waveform of the output from the output terminal (1) is as shown in FIG. 2 (d), and the waveform of the output from the output terminal (2) is as shown in FIG. 2 (e). As a result, the start trigger pulse generator 6 outputs a negative pulse which falls when the output of the output terminal (1) of the voltage comparator 1 falls as shown in FIG. 2 (f), and the stop trigger pulse is generated. From the device 9, the output terminal of the voltage comparator 1.
A negative pulse falling at the time of the output of OUT1 falling is output as shown in FIG. 2 (g).

However, the output terminal OU of the voltage comparator 1 as in the conventional example described above.
Fig. 2 (b)-
Although it has a temperature characteristic as indicated by a broken line in (e), the output from the start trigger pulse generator 6 is equivalent to the fall output from the output terminal ▲ ▼ of the voltage comparator 1. Therefore, the trigger pulse applied from the start trigger pulse generator 6 to the output terminal 13 is not affected by the temperature characteristic of the voltage comparator 1. Since the output from the stop trigger pulse generator 9 is equivalent to using the falling output from the output terminal OUT1 of the voltage comparator 1, the stop trigger pulse generator 9 outputs to the output terminal 14 The trigger pulse applied to is not affected by the temperature characteristics of the voltage comparator 1.

In addition, if the T _ON / T _OFF voltage is set to a low potential, the data selector
The output terminal OUT1 of the voltage comparator 1 is connected to the output terminal ▲ ▼ of 10
An inverted output of the output from, that is, an output having a waveform shown in FIG. 2 (e) is output, and a trigger pulse having a waveform shown in FIG. 2 (g) is output to the output terminal 13. The output terminal 1Y of the selector 10 is the inverted output of the output terminal ▲ ▼ of the voltage comparator, that is, the output of the waveform shown in FIG. 2 (d), and the output terminal 14 is shown in FIG. The trigger pulse having the waveform shown in () is output. Therefore, in this embodiment, when the output from the output terminal 13 starts counting the frequency and the output from the output terminal 14 stops the counting of the frequency, when the T _ON / T _OFF voltage is at a high potential, Can measure the section length of the signal input level above the reference voltage, and can measure the section length of the signal input level below the reference voltage when the T _ON / T _OFF voltage is low potential.

Further, when the output from the output terminal OUT1, ▲ ▼ of the voltage comparator 1 has a temperature characteristic in which the falling edge of the output slopes, the data selector 10 outputs the input without inverting the input signal of the reference voltage or more. When measuring the level section length, the output from the output terminal OUT1 of the voltage comparator 1 is supplied to the start trigger pulse generator 6, and the output terminal ▲
The output from ▼ is the stop trigger pulse generator 9
To be supplied to the data selector. Furthermore, when measuring the section length of the signal input level lower than the reference voltage, the output from the output terminal OUT1 of the voltage comparator 1 is supplied to the stop trigger pulse generator 9 and the output from the output terminal ▲ ▼ is started. It may be selected by the data selector so as to be supplied to the trigger pulse generator 6.

(Effect of the Invention) As described above, according to the present invention, the edge of the output of the voltage comparator which does not have the temperature characteristic is selected by the selector and is supplied to the first and second trigger pulse generators. Since the first and second trigger pulses are configured so as to be independent of the temperature characteristic of the output of the voltage comparator, the section length can be accurately measured. Further, the same effect can be obtained when a certain count value is subtracted from the start pulse to start and the section length is measured.

[Brief description of drawings]

FIG. 1 is a block diagram showing the construction of an embodiment of the present invention. FIG. 2 is a timing chart for explaining the operation of one embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the conventional example. FIG. 4 is a timing chart for explaining the operation of the conventional example. 1 ... Voltage comparator, 6 ... Start trigger pulse generator, 9 ... Stop trigger pulse generator, 10 ... Data selector.

Claims (1)

[Claims] 1. A section length measuring circuit for measuring a first section length in which a signal input level is equal to or higher than a reference voltage or a second section length in which a signal input level is lower than a reference voltage. A voltage comparator for comparing with a reference voltage and first and second pulses for outputting a pulse of a predetermined width from the edge of the input signal.
Of the trigger pulse generator and the output of the voltage comparator on the positive polarity side and the output on the negative polarity side, and the output of the voltage comparator from the output related to the input with the selection signal related to the type of the measurement interval length. And a data selector which supplies the first and second trigger pulse generators with the edge side which does not have the temperature characteristic.