JP4484015B2 - Clock waveform distortion determination method and clock waveform distortion determination apparatus in transmission simulation or actual measurement - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a clock waveform distortion determination method and a clock waveform distortion determination apparatus in transmission simulation or actual measurement.
[0002]
[Prior art]
As a conventional technique, with respect to digital luminance data, an absolute value and polarity of a primary difference that is a difference in data value between a certain pixel and a pixel before one clock are detected, and the primary difference is detected by a predetermined bit. Encodes a number of encoded signals and generates a contour compensation component that matches the luminance signal, so that desired contour compensation characteristics can be obtained without ringing or waveform distortion, and a small number of gates can be easily obtained. There is a video processing method that can have a simple circuit configuration (see, for example, Patent Document 1).
[0003]
Further, waveform distortion determination is performed by half-wave rectifying the waveform from the first differentiation section and the waveform from the second differentiation section and counting the number of negative pulses of the waveform to determine whether the signal under measurement is normal or abnormal. There is also a method (for example, refer to Patent Document 2).
[0004]
In addition to ringing and stepping due to reflection noise, there is a technique for detecting waveform disturbance by analyzing the duty ratio from the pulse period of the waveform for the signal waveform of the transmission line (see Non-Patent Document 1, for example). According to Non-Patent Document 1, the time required to reach the rise time from the low level threshold to the high level threshold from the clock waveform data in the form of a two-dimensional vector of time and voltage obtained in the transmission simulation. If the fall time is defined as the time from the high level / threshold value to the low level / threshold value, the rise time and fall time are detected in advance by a predetermined value. The failure is judged by whether or not the time is exceeded.
[0005]
[Patent Document 1]
JP 2002-232744 A [Patent Document 2]
JP 2003-14797 A [Non-Patent Document 1]
Jiro Inagaki and four others, “Analysis Method of Signal Waveforms on Transmission Lines of High-Speed Digital Lines”, Proceedings of the 2002 IEICE General Conference, IEICE, 2002, SA-1-3, p. 434
[0006]
[Problems to be solved by the invention]
With the determination method of Non-Patent Document 1, it is impossible to detect minute waveform distortion that occurs in a time shorter than a predetermined value. The present invention does not simply detect time, but automatically detects waveform distortion itself.
[0007]
An object of the present invention is to provide a clock waveform distortion determination method and a clock waveform distortion determination apparatus that can automatically determine waveform distortion in transmission simulation or actual measurement.
[0008]
[Means for Solving the Problems]
The clock waveform distortion determination method of the present invention includes:
From the clock waveform data in the form of a two-dimensional vector of time and voltage obtained by the transmission simulation, the rise time is arbitrarily set from the first threshold voltage value (hereinafter referred to as low level threshold value ). It is defined as the time to reach a second threshold voltage value (hereinafter defined as a high level threshold value) that is higher than the first threshold voltage value by an arbitrary voltage , and the falling time is set to a high level. In the clock waveform distortion determination method in the state where the voltage level is transitioning, such as rise time or fall time, it is defined as the time from threshold to low level threshold.
(Voltage value at a certain time minus voltage value at the previous time) ÷ (A certain time minus the time before one) (here, defined as the amount of change on the first floor) and the sign of the amount of change on the first floor From the sign of, it is detected whether it is monotonically increasing within the rise time or monotonically decreasing within the fall time, and further, (change amount of the first floor of a certain time minus change of the first floor of the previous time) (Amount) ÷ (A certain time minus 1 time before) (here, defined as the amount of change on the second floor), count the number of times the amount of change on the second floor is 0, and the number of times 0 is 2 or more if, clock waveform distortion is detected Yu Rukoto.
[0009]
The clock waveform distortion determination method of the present invention includes:
The rise time is defined as the time from the low level / threshold value to the high level / threshold value from the clock waveform data in the form of two-dimensional vector of time and voltage obtained by actual measurement, and the fall time is set high. In the clock waveform distortion determination method in the state where the voltage level is transitioning, such as rise time or fall time, it is defined as the time to reach from the level / threshold to the low level / threshold.
(Voltage value at a certain time minus voltage value at the previous time) ÷ (A certain time minus the time before one) (here, defined as the amount of change on the first floor) and the sign of the amount of change on the first floor From the sign of, it is detected whether it is monotonically increasing within the rise time or monotonically decreasing within the fall time, and further, (change amount of the first floor of a certain time minus change of the first floor of the previous time) (Amount) ÷ (A certain time minus 1 time before) (here, defined as the amount of change on the second floor), count the number of times the amount of change on the second floor is 0, and the number of times 0 is 2 or more if, clock waveform distortion is detected Yu Rukoto.
[0010]
As an alternative to the number of times the second floor change amount becomes 0, the number of times the second floor change amount changes from positive to negative, or from negative to positive, and if the number of changes is two or more, the clock The presence of waveform distortion may be detected.
[0011]
The clock waveform distortion determination apparatus of the present invention is
From the clock waveform data in the form of a two-dimensional vector of time and voltage obtained in the transmission simulation, the rise time is defined as the time to reach from the low level threshold to the high level threshold, and the fall time is defined as In the clock waveform distortion determination device in the state where the voltage level is transitioning, such as rise time or fall time, defined as the time to reach from the high level / threshold to the low level / threshold,
(Voltage value at a certain time minus voltage value at the previous time) ÷ (A certain time minus the time before one) (here, defined as the amount of change on the first floor) and the sign of the amount of change on the first floor , And means for detecting whether it is monotonically increasing within the rise time or monotonically decreasing within the fall time. First floor change) ÷ (A certain time minus one previous time) (here, defined as the second floor change), count the number of times the second floor change is zero, and count to zero There be two or more times, with means clock waveform distortion detecting a chromatic Rukoto.
[0012]
The clock waveform distortion determination apparatus of the present invention is
The rise time is defined as the time from the low level / threshold value to the high level / threshold value from the clock waveform data in the form of two-dimensional vector of time and voltage obtained by actual measurement, and the fall time is set high. In the clock waveform distortion determination device in the state where the voltage level is transitioning, such as rise time or fall time, it is defined as the time to reach from the level / threshold to the low level / threshold
(Voltage value at a certain time minus voltage value at the previous time) ÷ (A certain time minus the time before one) (here, defined as the amount of change on the first floor) and the sign of the amount of change on the first floor , And means for detecting whether it is monotonically increasing within the rise time or monotonically decreasing within the fall time. First floor change) ÷ (A certain time minus one previous time) (here, defined as the second floor change), count the number of times the second floor change is zero, and count to zero There be two or more times, with means clock waveform distortion detecting a chromatic Rukoto.
[0013]
As an alternative to the number of times the second floor change amount becomes 0, the number of times the second floor change amount changes from positive to negative, or from negative to positive, and if the number of changes is two or more, the clock Means for detecting the presence of waveform distortion may be provided.
[0014]
The clock signal is a basic signal for the operation of the electronic circuit, and clock waveform shaping is important. Usually, the simulation result is visually checked for waveform distortion. However, if the present invention is used, it is automatic. Can be determined.
[0015]
In addition, by using this method for the result of sampling a waveform actually measured with an oscilloscope, it can be applied to the measured waveform by realizing a function for indicating the possibility of a failure.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a flowchart as an embodiment of the present invention is shown. First, waveform data obtained by simulation or actual measurement is prepared. In general, the result of numerical analysis is a discrete value as shown in FIG. 2, and particularly in the case of waveform data, takes the form of a two-dimensional vector of (time, voltage). Here, the rise time is defined as the time from the low level threshold to the high level threshold (Figure 2), and the fall time is from the high level threshold to the low level threshold. It is defined as the time to reach. These threshold values must be set in advance or input every time this determination method is executed. This will be described with reference to the example of rising in FIG. First, a rising portion sandwiched between a low level threshold and a high level threshold is detected. Here, this detection method does not matter. The data set in the rising portion is represented by [t (1), V (1)], [t (2), V (2)]... [T (i), V (i)]. t (n), V (n)]. The amount of change on the first floor is calculated. The arithmetic expression is
V ′ (i) = {V (i) −V (i−1)} ÷ {t (i) −t (i−1)} (i = 2, 3 ·· n) (1). Simultaneously with this calculation, the sign of V ′ (i) is recorded. In the case of rising, if V ′ (i) <0 exists, a warning is given if there is waveform distortion, and the process ends. (In the case of falling, a warning is given by V ′ (i)> 0) Here, when there is no warning of waveform distortion, the data set [t (2), V ′ (2)], [t (3), V ′ (3)]... [T (i), V (i)]... [T (n), V ′ (n)] is further calculated as the second-order variation. The arithmetic expression is
V ″ (i) = {V ′ (i) −V ′ (i−1)} ÷ {t (i) −t (i−1)} (i = 3, 4 ·· n) (2) It is. Here, V ″ (i) = 0 should be detected. However, since the data handled is a discrete value, V ″ (i) = 0 cannot often be detected. Therefore, if the sign of V ″ (i) is recorded, and the number of times V ″ (i) changes from positive to negative or from negative to positive as i increases, Similar detection can be considered. If a sign change is detected two or more times from this result, the process ends with attention to the possibility of waveform distortion. If the sign change is once or less, it is assumed that there is no problem with this waveform, and the process ends.
[0017]
Next, the operation of the embodiment of the present invention will be described with reference to FIGS.
[0018]
Usually, the clock is considered significant, capturing the moment of change of rising, falling, or both. Therefore, for example, in a waveform in which the voltage drops within the rise time as shown in FIG. 4, it is considered that there is significance twice in one rise time, and a malfunction may occur. As shown in FIG. 3, the clock waveform must increase or decrease monotonically during the rise time and fall time. On the other hand, in the waveform shown in FIG. 5, since the condition of monotonic increase necessary for the clock waveform is satisfied, it may seem that there is no problem with the clock waveform. However, since there is a step in one rise time, the time that is considered significant is not constant, and the time fluctuation (called jitter) increases in the next stage signal, or the time of high level and low level There is a possibility that a problem such as variation in the ratio (referred to as duty) appears. This is because the original threshold value that determines the high level and the low level is between the high level threshold value and the low level threshold value. This is because it also fluctuates.
[0019]
Here, the principle of detecting the faults in FIGS. 4 and 5 will be described. In other words, the expression (1) represents the amount of voltage change per unit time during the rise time or fall time. This corresponds to the first derivative of the continuous function. It is obvious that if the formula (1) is positive, it is monotonically increasing, and if it is negative, it is monotonically decreasing. Therefore, by monitoring the sign of equation (1), the waveform defect corresponding to FIG. 4 can be detected.
[0020]
Since the problem of FIG. 5 cannot be detected only by the expression (1), the expression (2) is further introduced. This corresponds to the second-order differentiation of the continuous function, and indicates how the voltage change amount changes. That is, if the expression (2) is positive at the rise time, the increase in voltage is further accelerated, and if it is negative, the increase is decelerated, and the voltage starts to decrease. This change point is determined when equation (2) = 0. That is, at this point, the waveform changes from convex downward to convex upward, or from convex upward to convex downward. Therefore, in the waveform as shown in FIG. 3, the expression (2) = 0 is only once during the rise time or the fall time, but in FIG. 4 and FIG. 5, the expression (2) = 0. Appears several times, and by counting this number of times, a defect can be detected. However, since the present invention deals with discrete values, there is a possibility that the condition (2) = 0 cannot be found. Therefore, if a point that changes from positive to negative or from negative to positive between a certain time t (i) and the next time t (i + 1) is detected, 0 is detected between t (i) and t (i + 1). There should be a place to become. (Strictly speaking, since it is a discrete value, there is no numerical value in the meantime.)
Here, the principle of occurrence of a waveform defect will be described with reference to FIG. In general, the signal output from the output buffer A is reflected from the moment when it reaches the farthest input buffer (D in the figure). This is because the input impedance of the input buffer is very large and causes total reflection. The input buffer of D can receive an undistorted waveform because the traveling wave and the reflected wave reach simultaneously. However, in the B and C input buffers, the arrival time of the traveling wave and the reflected wave is shifted, so that the waveform is distorted. This waveform distortion may cause a malfunction of the circuit of the next stage, and it is very useful to find and correct a defect in advance by simulation.
[0021]
(Another embodiment of the invention)
The embodiment of the invention described above refers to the simulation result. For example, by using this method for the result of sampling the waveform actually measured with an oscilloscope, it is pointed out that there is a problem with the measured waveform. It can be applied to realize functions to perform.
[0022]
【The invention's effect】
As described above, the present invention has the following effects.
[0023]
Design and manufacture of a printed circuit board are costly and time consuming, and it is very useful to detect in advance by simulation or the like during printed circuit board design. In particular, the clock signal is a basic signal for the operation of the electronic circuit, and clock waveform shaping is important. Usually, the simulation result visually confirms whether there is waveform distortion. However, if the present invention is used, it can be automatically determined.
[0024]
In addition, by using this method for the result of sampling a waveform actually measured with an oscilloscope, it can be applied to the measured waveform by realizing a function for indicating the possibility of a failure.
[Brief description of the drawings]
FIG. 1 is a diagram showing a flowchart as an embodiment of the present invention.
FIG. 2 is a diagram showing waveform data obtained as a result of numerical analysis.
FIG. 3 is a diagram showing waveform data as a result of numerical analysis.
FIG. 4 is a diagram showing waveform data obtained as a result of numerical analysis.
FIG. 5 is a diagram showing waveform data obtained as a result of numerical analysis.
FIG. 6 is a diagram for explaining the principle of occurrence of a waveform defect.
[Explanation of symbols]
A Output buffer B, C, D Input buffer

Claims (8)

From the clock waveform data in the form of a two-dimensional vector of time and voltage obtained by the transmission simulation, the rise time is arbitrarily set from the first threshold voltage value (hereinafter referred to as low level threshold value ). It is defined as the time to reach a second threshold voltage value (hereinafter defined as a high level threshold value) that is higher than the first threshold voltage value by an arbitrary voltage , and the falling time is set to a high level. In the clock waveform distortion determination method in the state where the voltage level is transitioning, such as rise time or fall time, it is defined as the time from threshold to low level threshold.
(Voltage value at a certain time minus voltage value at the previous time) / (A certain time minus the previous time) is calculated (here, defined as the amount of change in the first floor), and the amount of change in the first floor is calculated. From the sign of positive / negative, it is detected whether it is monotonically increasing within the rise time or monotonically decreasing within the fall time, and further, (change amount of the first floor of a certain time minus the first floor of the previous time) variation) performs ÷ (certain operation time -1 previous time) (defined as the second floor of the variation in this case), counts the number of times that the amount of change in the second floor is 0, the number of times that the said 0 if two or more times, the clock waveform distortion determination method characterized by clock waveform distortion detecting a chromatic Rukoto.   As an alternative to the number of times the second floor change amount becomes 0, the second floor change amount counts the number of changes from positive to negative, or from negative to positive, and if the number of changes is two or more, 2. The clock waveform distortion determination method according to claim 1, wherein the presence of clock waveform distortion is detected. The rise time is defined as the time from the low level / threshold value to the high level / threshold value from the clock waveform data in the form of two-dimensional vector of time and voltage obtained by actual measurement, and the fall time is set high. In the clock waveform distortion determination method in the state where the voltage level is transitioning, such as rise time or fall time, it is defined as the time to reach from the level / threshold to the low level / threshold.
(Voltage value at a certain time minus voltage value at the previous time) / (A certain time minus the previous time) is calculated (here, defined as the amount of change in the first floor), and the amount of change in the first floor is calculated. From the sign of positive / negative, it is detected whether it is monotonically increasing within the rise time or monotonically decreasing within the fall time, and further, (change amount of the first floor of a certain time minus the first floor of the previous time) variation) performs ÷ (certain operation time -1 previous time) (defined as the second floor of the variation in this case), counts the number of times that the amount of change in the second floor is 0, the number of times that the said 0 if two or more times, the clock waveform distortion determination method characterized by clock waveform distortion detecting a chromatic Rukoto.   As an alternative to the number of times the second floor change amount becomes 0, the second floor change amount counts the number of changes from positive to negative, or from negative to positive, and if the number of changes is two or more, 4. The clock waveform distortion determination method according to claim 3, wherein the presence of clock waveform distortion is detected. From the clock waveform data in the form of a two-dimensional vector of time and voltage obtained in the transmission simulation, the rise time is defined as the time to reach from the low level threshold to the high level threshold, and the fall time is defined as In the clock waveform distortion determination device in the state where the voltage level is transitioning, such as rise time or fall time, defined as the time to reach from the high level / threshold to the low level / threshold,
(Voltage value at a certain time minus voltage value at the previous time) / (A certain time minus the previous time) is calculated (here, defined as the amount of change in the first floor), and the amount of change in the first floor is calculated. Means for detecting from a positive or negative sign whether it is monotonically increasing within a rise time or monotonically decreasing within a fall time;
Further, the calculation of (change amount of the first floor of a certain time minus the change amount of the first floor of the previous time) / (time of one time minus the previous time) (here, defined as the change amount of the second floor) is performed. the second floor of the change amount is counted the number of times becomes 0, if the number of times that the said 0 more than once, clock waveform distortion determination, characterized in that it comprises means for clock waveform distortion is detected chromatic Rukoto apparatus.   As an alternative to the number of times the second floor change amount becomes 0, the second floor change amount counts the number of changes from positive to negative, or from negative to positive, and if the number of changes is two or more, 6. The clock waveform distortion determination apparatus according to claim 5, further comprising means for detecting the presence of clock waveform distortion. The rise time is defined as the time from the low level / threshold value to the high level / threshold value from the clock waveform data in the form of two-dimensional vector of time and voltage obtained by actual measurement, and the fall time is set high. In the clock waveform distortion determination device in the state where the voltage level is transitioning, such as rise time or fall time, it is defined as the time to reach from the level / threshold to the low level / threshold.
(Voltage value at a certain time minus voltage value at the previous time) / (A certain time minus the previous time) is calculated (here, defined as the amount of change in the first floor), and the amount of change in the first floor is calculated. Means for detecting from a positive or negative sign whether it is monotonically increasing within a rise time or monotonically decreasing within a fall time;
Further, the calculation of (change amount of the first floor of a certain time minus the change amount of the first floor of the previous time) / (time of one time minus the previous time) (here, defined as the change amount of the second floor) is performed. the second floor of the change amount is counted the number of times becomes 0, if the number of times that the said 0 more than once, clock waveform distortion determination, characterized in that it comprises means for clock waveform distortion is detected chromatic Rukoto apparatus.   As an alternative to the number of times the second floor change amount becomes 0, the second floor change amount counts the number of changes from positive to negative, or from negative to positive, and if the number of changes is two or more, 8. The clock waveform distortion determination apparatus according to claim 7, further comprising means for detecting the presence of clock waveform distortion.

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