JPS59122966A - Measurement of delay time - Google Patents

Abstract

PURPOSE:To easily perform the highly precise measurement of a wide range of a delay time, by generating a delay pulse reduced in the change of rising characteristics by applying a deformed pulse which is subjected to longterm delaying to be made easily observable. CONSTITUTION:The primary pulse Pa of the cycle tau1 outputted by a variable cycle oscillator 1 is counted by a multi-base number system count circuit 2 to be brought to a long-cycle pulse Pb and a secondary pulse Pc which becomes same to the pulse Pa in the rising thereof by adjusting the oscillator 2 on the basis of the observation of an oscilloscope 4 and subjected to longterm delaying to be made easily observable is outputted from a delay circuit 3. This pulse Pc is applied to a circuit 6 to be measured and a pulse Pd to be measured which is reduced in the change of rising characteristics avoided from reflected wave at the time of impedance unmatching by the long-cycle pulse Pc and is not varied in a threshold value is outputted. When a changed primary pulse Paa with a cycle tau2 is outputted from the oscillator 1 in synchronous relation to the pulse Pd in the rising thereof on the basis of the observation of the oscilloscope 4, the delay time T of the circuit 6 is determined from cycle difference tau1, tau2 and the highly precise measurement of a wide range of a delay time is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to improvements in methods for measuring time intervals in signal waveforms, particularly delay times.

佽）Technical Background Traditionally, there has been a method of using an oscilloscope or a counter as a means of observing analog or digital waveforms or measuring the time interval between multiple signals or signal change points, that is, the delay time difference between subsequent signals or change points. Widely used.

(e) Prior art and problems Oscilloscopes usually use a cathode ray tube (CRT) to apply an input signal voltage to one deflection means to make the bright spot swing in the Y direction, and at the same time deflect the bright spot in the X direction in synchronization with the input signal. The waveform of the input signal voltage is observed by sweeping with the deflection means.

It has a built-in input signal amplifier, two time axis generators, various adjustment circuits, etc., and is widely used as a means of observing signals with a DC frequency of several GHz. In addition to multi-phenomenon observation means that simultaneously measures multiple signals using ORT S having multiple sets of input signal deflection means or means for extracting instantaneous values using narrow sampling pulses synchronized with input signals, Since the device is equipped with a means for starting the sweep when a signal becomes a trigger, the sweep is started by a change point of the input signal, and by observing other subsequent input signals or other change points, the sweep is started at a 9-hour interval, for example, by observing another input signal or another change point. Although the delay time of the measurement circuit can be measured, the preceding signal that serves as the trigger is not necessarily a sharp falling edge or a falling pulse, which is the ideal condition for triggering, so the reference point may float due to fluctuations in the trigger level, and the delay time may vary. Depending on the value of , particularly when the well delay time is large, measurement accuracy cannot be obtained due to the relationship between the four-take accuracy. Another method using a counter is to start counting the reference clock using the gate of the calculator in response to a preceding input signal or change point, and to measure time by closing the gate in response to a subsequent input signal or change point. In addition to an easy reading method using a digital display, the reference clock has excellent accuracy and resolution of, for example, 1o/1m, but since the gate trigger of the counter is usually based on the signal level, gradual changes or complicated For signals with significant changes, it is inferior to visual observation using an oscilloscope in that there is no guarantee that the desired change point can be accurately captured.

(d) Object of the Invention The object of the present invention is to provide a delay time that is highly accurate and easy to handle by taking advantage of the advantages of visual observation in an oscilloscope and the advantages of a counter while eliminating the disadvantages of conventional time measurement using an oscilloscope. The aim is to provide a means of measurement.

(e) Structure of the Invention For this purpose, a means for generating a pulse waveform with an arbitrary repetition period, a means for measuring the repetition period of the pulse waveform, and a length having a repetition period of n times by applying the primary pulse by the pulse generation means are provided. A counting means for outputting a periodic pulse, a means for delaying the long-period pulse to generate a secondary pulse, and a timing observation means using an oscilloscope are provided, and the period measuring means is provided while changing the repetition period of the pulse generating means. and the observation means makes the rising edge of the next cycle of the primary pulse coincide with the rising edge of the secondary pulse @1
A second period ζ obtained by applying a period ζ 1, a secondary pulse to the circuit under test and making the rising edge of one cycle or a plurality of m cycles of the primary pulse coincide with the rising edge of the applied pulse to be measured.
2t or mζ3, the first period ζ1. and the second period ζ
This can be achieved by providing a delay time measuring method characterized in that the delay time of the circuit under test is determined by the time difference between mζ3 and mζ3.

(1) Embodiment of the invention An embodiment of the invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a delay time measuring method according to an embodiment of the present invention, and FIG. 2 is a time chart thereof.

In the figure, 14 is a variable period oscillator, and 2 is a counting circuit.

3 is a delay IL 21, 4 is an oscilloscope, 5 is a period measuring device, and 6 is a circuit under test (■) UT).

The variable period oscillator 1 sends out this primary pulse Pa continuously at a set repetition period or in synchronization with an external signal as required (not shown) to the counting circuit 2. The repetition period ζ is determined by the delay time T described later. The value should be set shorter than the expected value. The counting circuit 2, which has an n-ary counting function, converts the period of the primary pulse PQ into a long-period pulse PQ having a period n times the period, for example, four times the period here, and sends it to the delay circuit. This n, which is the delay time of the to11 counting circuit 2, can be any value and does not necessarily have to be in the form of 2, but in consideration of the expected delay time T, select a value that is large enough so that there is no problem during measurement. do. Here, the delay circuit 3 that receives the long-period pulse Pb gives an arbitrary delay time and sends out the secondary pulse pressure.
; - The variable period oscillator 1 is set to match the rising edge of i.
! ! 1, observe it on the screen of the oscilloscope 4, and obtain the first period ζ1 using the period measuring device 5.

Next, the secondary pulse Pc])1,1. T, 6 is applied to send out the pulse to be measured Pd to be measured, and the pulse to be measured Pd and the primary pulse Pa are sent to the oscilloscope 4.
While observing the rising edge of the secondary pulse Pc as a trigger, change the primary pulse Pa at the rising edge υ of the pulse to be measured Pd to complete the change after one cycle of the primary pulse Paa or Paa'. Or more than one n.

〃Synchronized measuring device 5vc by matching the rise after the cycle
It is better than the second period ζ2 or 〃ζ3. Here, if we obtain the difference between the second period ζ2 and the second period ζ2 or ts)/lζ3, the delay time T becomes T-ζl-ζ2 or Du by T-ζ1 to ζ3.
The delay time of Ta can be easily measured with high precision.

(2) As described in detail, according to the present invention, the pulse generated by the pulse generating means is transformed into a measurement pulse convenient for observation by the long delay stage 1c and applied to D7T, and the waveform is The coincidence of the rises is determined by waveform observation means that can be easily confirmed, and the delay time is determined by using a pulse generating means that is not affected by the slowing characteristics of the delayed pulse and has a state in which there is little change in the rise characteristics, that is, there is little change in the threshold value. No (by Luz,
1) It is possible to remove the error caused by the unclearness of the threshold value in the conventional method (applied measurement) (for example, high-speed rise because the Luss has a long period) (In the Luss, it is possible to eliminate the error caused by the unclearness of the threshold value) This method is useful because it is one of the methods for measuring delay times that can easily deal with a wide range of delay times without sacrificing accuracy, such as by easily avoiding effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a method for measuring delay time in an embodiment of the present invention, and FIG. 2 is a time chart. In the figure, 1 is a variable period oscillator, 2 is a counting circuit,
3 is a delay circuit, 4 is an oscilloscope, 5 is a circuit to be measured, and 6 is a period generator.

Claims (1)

[Claims] Means for generating a pulse waveform with an arbitrary repetition period; means for measuring the repetition period of the pulse waveform; counting means for applying the primary pulse of the pulse generating means to output a long-period pulse having a repetition period n times; A means for delaying the long-period pulse to reduce the secondary pulse to 7% and a timing observation means using an oscilloscope are provided, and while changing the repetition period of the pulse generation means, the period measurement means and observation means are used to monitor the rise of the secondary pulse. , the first period ζ1 that makes the rising edge of the next cycle in the primary pulse coincide with the rising edge of the pulse to be measured lCf1 which imprints the secondary pulse into the circuit under test, and the rising edge of one cycle or a plurality of m cycles of the primary pulse. The second period ζ2 or I to match the shi and dive
Read nζ3, first period ζ1, second period ζ2 and Fl
A method for measuring delay time characterized by subtracting the delay time of the circuit under test from the difference time from Inζ3