JP3508743B2 - Waveform distortion determination apparatus and waveform distortion determination method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform distortion judging apparatus and a waveform distortion judging method for judging distortion of a logic signal input to a logic element in a logic circuit, and more particularly to a waveform for judging distortion of a logic signal digitally. The present invention relates to a distortion determination device and a waveform distortion determination method.

[0002]

2. Description of the Related Art Conventionally, inversion of voltage (step) in a linear operation region or an active operation region between a logic 0 threshold voltage and a logic 1 threshold voltage of a logic signal input to a logic element in a logic circuit. Since there is a possibility that the logic element may malfunction, the waveform of the leading edge (rising edge) and the waveform of the trailing edge (falling edge) of the logic signal can be measured with an oscilloscope for stable operation of the logic circuit. The operator made a visual observation by using a device such as “A” to make a determination that there was no voltage reversal.

[0003]

However, in the prior art, there are individual differences in the confirmation and determination of waveforms between measuring persons, and even when it is necessary to determine an abnormality by overlooking a subtle step or the like. There is a problem that it may be judged as normal, and a correct judgment cannot always be made.

The present invention has been made in view of the above problems, and an object thereof is to provide a leading edge waveform and a trailing edge waveform of a logic signal input to a logic element in a logic circuit. It is to provide a waveform distortion determination device and a waveform distortion determination method that can always make a correct determination without missing a subtle level difference by digitally determining.

[0005]

The present invention has the following constitution in order to solve the above problems. The gist of the invention according to claim 1 is a waveform distortion determination device for determining distortion of a logic signal input to a logic element in a logic circuit, the first differentiation means for differentiating the logic signal, and the first differentiation means. Second differentiating means for further differentiating the waveform differentiated by the means, and judging means for judging whether the logic signal is normal or abnormal based on the output from the first differentiating means and the output from the second differentiating means. A waveform distortion determination device characterized by being provided. The gist of the invention according to claim 2 resides in the waveform distortion determination device according to claim 1, wherein the determination means determines whether the logic signal is normal or abnormal by counting the number of pulses. . The gist of the invention according to claim 3 further comprises a passage switch means for cutting out a waveform of one cycle of the logic signal, and the first differentiating means differentiates the waveform cut out by the passage switch means. The waveform distortion determination device according to claim 1 or 2 is characterized. A fourth aspect of the present invention is to provide a slicing means for slicing the waveform cut out by the passage switch means with an arbitrarily set lower limit voltage and upper limit voltage, and amplifying the sliced waveform by the slicing means. The waveform distortion determination apparatus according to claim 1, further comprising an amplifying unit, wherein the first differentiating unit differentiates the waveform amplified by the amplifying unit. A fifth aspect of the present invention is characterized in that the lower limit voltage and the upper limit voltage at the time of slicing by the slicing means are threshold voltages for logic determination of the logic element. The waveform distortion determination device according to any one of 4 above. A sixth aspect of the present invention is a waveform distortion determination method for determining distortion of a logic signal input to a logic element in a logic circuit, wherein the logic signal is differentiated to generate a first differential waveform, A waveform characterized by further differentiating the first differential waveform to generate a second differential waveform, and determining whether the logic signal is normal or abnormal based on the first differential waveform and the second differential waveform. Exists in the distortion determination method. Further, the gist of the invention according to claim 7 is that whether the logic signal is normal or abnormal is determined by counting the number of pulses of each of the first differential waveform and the second differential waveform. It exists in the described waveform distortion determination method. Further, the gist of the invention according to claim 8 is that the waveform of one cycle of the logic signal is cut out, and the cut-off waveform is differentiated to generate the first differential waveform. It exists in the described waveform distortion determination method. Further, the gist of the invention according to claim 9 is to slice the cut-off waveform with an arbitrarily set lower limit voltage and upper limit voltage, amplify the sliced waveform, and differentiate the amplified waveform to differentiate the first waveform. The waveform distortion determination method according to any one of claims 6 to 8, wherein a differential waveform is generated. Further, the gist of the invention according to claim 10 is that the lower limit voltage and the upper limit voltage at the time of slicing are threshold voltages for logic determination of the logic element, respectively. The waveform distortion determination method described in (1) exists.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an embodiment of a waveform distortion determination device according to the present invention.

In this embodiment, the probe unit 1, the passage switch control unit 2, the passage switch unit 3, and the slice unit 4 are provided.
And an amplifying section 5, a first differentiating section 6, a first rectifying section 7, a second differentiating section 8, a second rectifying section 9 and a detecting section 10, such as a TTL (transistor transistor logic). Determine whether the logic signal of the logic circuit (circuit under test) is normal or abnormal.

The probe section 1 uses a circuit having a high impedance and a wide band as compared with the circuit under test so that the circuit under test draws almost no current and inputs a signal under measurement from the circuit under test.

The pass-switch control section 2 determines, based on the signal under measurement or a signal having a fixed relationship with the signal under measurement,
A timing signal required to pass one cycle of the signal under measurement is created.

The pass switch unit 3 is an analog switch and sends out one cycle of the signal under measurement to the slice unit 4 of the next stage based on the timing signal generated by the pass switch control unit 2.

The slicing unit 4 selects and cuts a waveform from an arbitrary lower limit voltage (Vsl) to an upper limit voltage (Vsh) having an arbitrary voltage width (Vδ) with respect to the ground potential, and amplifies the next stage. It is sent to the unit 5. The lower limit voltage value (V
sl) and the voltage width (Vδ) can be set to arbitrary values. By setting the lower limit voltage (Vsl) to the threshold voltage of logic 0 and the upper limit voltage (Vsh) to the threshold voltage of logic 1, the linear operation region of the logic element can be cut off. T
In the case of TL, the lower limit voltage (Vsl) may be 800 mV and the upper limit voltage (Vsh) may be 2V.

The amplifying section 5 amplifies the waveform whose amplitude is reduced by being sliced by the slicing section 4 and sends it to the first differentiating section 6 in the next stage.

The first differentiating section 6 and the second differentiating section 8 differentiate the outputs from the amplifying section 5 and the first differentiating section 6, respectively,
It outputs a voltage according to the slope of the waveform. That is, when the voltage value of the waveform increases, the positive output is output, when it decreases, the negative output, and when there is no change, 0V is output. First differentiator 6
Sends the differentiated waveform to the first rectifying unit 7 and the second differentiating unit 8, and the second differentiating unit 8 sends the differentiated waveform to the second rectifying unit 9.

The first rectifying section 7 and the second rectifying section 9 half-wave rectify the outputs from the first differentiating section 6 and the second differentiating section 8, respectively, to eliminate the positive polarity output, and the negative polarity output to the next. It is sent to the stage detection unit 10.

The detection unit 10 counts the negative polarity pulses of the output from the first rectification unit 7 and the output of the second rectification unit 9 based on the timing signal from the passage switch control unit 2, and outputs the negative polarity pulse. Whether the signal under measurement is normal or abnormal is determined based on the count result of.

Next, the operation of the present embodiment will be described in detail with reference to FIGS. 2 is a diagram showing a state transition of a waveform when a normal measured signal is input to the waveform distortion determination device shown in FIG. 1, and FIG. 3 is a front edge portion of the waveform distortion determination device shown in FIG. FIG. 4 is a diagram showing a state transition of a waveform when a signal under measurement having a step is input to the waveform distortion determining device shown in FIG. It is a figure which shows the state transition of the waveform at the time of being input, and FIG. 5 is a determination table which shows the determination result in the detection part shown in FIG.

First, the case where a normal signal under measurement (A1) is input will be described with reference to FIG. The normal measured signal (A1) input to the probe unit 1 is sent from the probe unit 1 to the passage switch unit 3 and the passage switch unit 3
Under the control of the passage switch control unit 2, the waveform for one cycle is extracted, and the extracted waveform for one cycle is sent to the slice unit 4.

The slicing unit 4 cuts (A2) the waveform between the lower limit voltage (Vsl) and the upper limit voltage (Vsh) with respect to the ground potential, sends the cut waveform (A2) to the amplifying unit 5, and the amplifying unit 5 5 amplifies the waveform (A2) (A3),
The amplified waveform (A3) is sent to the first differentiator 6. When the measured signal (A1) is normal, the cut waveform (A2)
The amplified waveform (A3) is a signal in which the leading edge (rising edge) and the trailing edge (falling edge) change uniformly, and there is no large change in step (decrease in voltage level) or slope.

The first differentiating section 6 differentiates the waveform (A3) (A4) and sends the differentiated waveform (A4) to the first rectifying section 7 and the second differentiating section 8. When the signal under measurement (A1) is normal, the leading edge portion and the trailing edge portion of the waveform (A3) amplified by slicing have a uniform change.
From the waveform (A4) output from, one positive pulse is obtained at the leading edge and one negative pulse is obtained at the trailing edge.

The first rectifying section 7 deletes the positive polarity pulse by half-wave rectifying the waveform (A4) from the first differentiating section 6 (A5), and the half-wave rectified waveform (A5) is detected by the detecting section 10. Send to. When the signal under measurement (A1) is normal, one pulse of negative polarity is obtained at the trailing edge of the half-wave rectified waveform (A5).

The second differentiating section 8 further differentiates the waveform (A4) from the first differentiating section 6 (A6), and differentiates the waveform (A6).
Is sent to the second rectification unit 9. When the signal under measurement (A1) is normal, the differentiated waveform (A6) has one positive pulse and one negative pulse at the leading edge and one negative pulse at the trailing edge. One positive pulse is obtained.

The second rectifying section 9 removes the positive pulse by half-wave rectifying the waveform (A6) from the second differentiating section 8 (A7), and the half-wave rectified waveform (A5) is detected by the detecting section 10. Send to. When the signal under test (A1) is normal, the half-wave rectified waveform (A7) has a total of two negative polarity pulses, one at the leading edge and one at the trailing edge.

The detection unit 10 counts the number of negative polarity pulses of the waveform (A5) from the first rectification unit 7 and the waveform (A7) from the second rectification unit 9, respectively, and displays them in the judgment table shown in FIG. Based on this, it is determined whether the signal under measurement (A1) is normal or abnormal, and the determination result is displayed on a display or the like not shown. Since the measured signal (A1) is normal, one waveform (A5) from the first rectifying unit 7 and one waveform (A5 from the second rectifying unit 9
Two negative pulses are obtained in 7).

Next, the measured signal (B
The case where 1) is input will be described with reference to FIG. The signal to be measured (B1) having a step at the front edge, which is input to the probe unit 1, is transmitted from the probe unit 1 to the passage switch unit 3
And the passage switch unit 3 is connected to the passage switch control unit 2
Under the control of 1, the waveform for one cycle is extracted, and the extracted waveform for one cycle is sent to the slice unit 4.

The slicing unit 4 cuts (B2) the waveform between the lower limit voltage (Vsl) and the upper limit voltage (Vsh) with respect to the ground potential, sends the cut waveform (B2) to the amplification unit 5, and the amplification unit 5 5 amplifies the waveform (B2) (B3),
The amplified waveform (B3) is sent to the first differentiator 6. When the measured signal (B1) has a step at the front edge, the cut waveform (B2) and the amplified waveform (B3) are signals having a large step at the front edge.

The first differentiating section 6 differentiates the waveform (B3) (B4) and sends the differentiated waveform (B4) to the first rectifying section 7 and the second differentiating section 8. If there is a step at the front edge of the signal under measurement (B1), the waveform (B
Since there is a large step at the leading edge of 3), the waveform (B4) output from the first differentiator 6 has two positive polarity pulses, one negative polarity pulse, and one negative polarity pulse at the leading edge. One negative pulse is obtained at the edge.

The first rectifying unit 7 deletes the positive pulse by half-wave rectifying the waveform (B4) from the first differentiating unit 6 (B5), and the half-wave rectified waveform (B5) is detected by the detecting unit 10. Send to. When the measured signal (B1) has a step at the front edge, the half-wave rectified waveform (B5) has one at the front edge,
Two negative polarity pulses are obtained, one at the trailing edge.

The second differentiating section 8 further differentiates the waveform (B4) from the first differentiating section 6 (B6) and differentiates the waveform (B6).
Is sent to the second rectification unit 9. When the measured signal (B1) has a step at the leading edge, the differentiated waveform (B6) has three positive pulses and four negative pulses at the leading edge and a negative polarity at the trailing edge. One pulse and one positive pulse are obtained.

The second rectifying section 9 removes the positive polarity pulse by half-wave rectifying the waveform (B6) from the second differentiating section 8 (B7), and the half-wave rectified waveform (B5) is detected by the detecting section 10. Send to. When the measured signal (B1) has a step at the leading edge, the half-wave rectified waveform (B7) has four points at the leading edge.
A total of 5 negative polarity pulses are obtained, one at the trailing edge.

The detecting section 10 counts the number of negative polarity pulses of the waveform (B5) from the first rectifying section 7 and the waveform (B7) from the second rectifying section 9, respectively, and the result is shown in the judgment table shown in FIG. Based on this, it is determined whether the signal under measurement (B1) is normal or abnormal, and the determination result is displayed on a display (not shown) or the like. When there is a step at the front edge of the signal under measurement (B1), there are two negative polarity pulses in the waveform (B5) from the first rectifying unit 7 and five negative polarity pulses in the waveform (B7) from the second rectifying unit 9. It is obtained and judged to be abnormal.

Next, the case where the signal under measurement (C1) in which the inclination of the front edge changes midway is input will be described with reference to FIG. The signal to be measured (C1), which is input to the probe unit 1 and whose inclination of the leading edge portion changes midway, is sent from the probe unit 1 to the pass switch unit 3, and the pass switch unit 3 controls the pass switch control unit 2. Based on the above, the waveform for one cycle is extracted, and the extracted waveform for one cycle is sent to the slice unit 4.

The slicing unit 4 cuts (C2) the waveform between the lower limit voltage (Vsl) and the upper limit voltage (Vsh) with respect to the ground potential, sends the cut waveform (C2) to the amplifying unit 5, and the amplifying unit 5 5 amplifies the waveform (C2) (C3),
The amplified waveform (C3) is sent to the first differentiator 6. When the inclination of the front edge of the signal under measurement (C1) changes midway,
Clipped waveform (C2) and amplified waveform (C3)
Is a signal with a large change in the inclination of the leading edge.

The first differentiating section 6 differentiates the waveform (C3) (C4) and sends the differentiated waveform (C4) to the first rectifying section 7 and the second differentiating section 8. When the inclination of the leading edge of the signal under measurement (C1) changes in the middle, there is a large inclination change in the leading edge of the waveform (C3) amplified by slicing. In the waveform (C4) to be generated, one positive polarity pulse having a distortion at the leading edge portion and one negative polarity pulse at the trailing edge portion are obtained.

The first rectifying unit 7 deletes the positive pulse by half-wave rectifying the waveform (C4) from the first differentiating unit 6 (C5), and the half-wave rectified waveform (C5) is detected by the detecting unit 10. Send to. When the slope of the leading edge portion of the signal under measurement (C1) changes midway, the negative waveform pulse is obtained at the trailing edge portion in the half-wave rectified waveform (C5).

The second differentiating section 8 further differentiates the waveform (C4) from the first differentiating section 6 (C6), and differentiates the waveform (C6).
To the second rectification unit. When the slope of the front edge of the signal under measurement (C1) changes in the middle, the differentiated waveform (C6)
Has two positive and two negative pulses at the leading edge and one negative and one positive pulse at the trailing edge.
You can get one.

The second rectifying section 9 removes the positive pulse by half-wave rectifying the waveform (C6) from the second differentiating section 8 (C7), and the half-wave rectified waveform (C5) is detected by the detecting section 10. Send to. When the inclination of the front edge of the signal under measurement (C1) changes in the middle, the half-wave rectified waveform (C7) has two negative electrodes at the front edge and three negative electrodes at the rear edge. A sex pulse is obtained.

The detecting section 10 counts the number of negative polarity pulses of the waveform (C5) from the first rectifying section 7 and the waveform (C7) from the second rectifying section 9, respectively. Based on this, it is determined whether the signal under measurement (C1) is normal or abnormal, and the determination result is displayed on a display or the like not shown. When the inclination of the front edge of the signal under measurement (C1) changes on the way, one in the waveform (C5) from the first rectifying unit 7, the second
Three negative polarity pulses are obtained in the waveform (C7) from the rectification unit 9, and it is determined that the pulse is abnormal.

As described above, according to the present embodiment, the negative polarity pulse is obtained by differentiating and rectifying the waveform of the leading edge portion and the waveform of the trailing edge portion of the logic signal input to the logic element in the logic circuit. Is generated, and the generated negative polarity pulse is counted to digitally determine whether the pulse is normal or abnormal. Therefore, it is possible to always make a correct determination without missing a subtle step or the like.

Further, according to the present embodiment, the waveform between the lower limit voltage (Vsl) and the upper limit voltage (Vsh) is cut in the slicing unit 4, and the cut waveform is amplified by the amplifying unit 5 to increase the gain. Since the determination is performed based on the waveform in which the leading edge and the trailing edge are enlarged, it is possible to detect the presence or absence of a minute step in the logic signal and the presence or absence of a slight change in the inclination, and it is possible to improve the accuracy of the determination. Has the effect.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it is apparent that each embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, etc. of the above-mentioned constituent members are not limited to those in the above-mentioned embodiment, and the number, position, shape, etc. suitable for carrying out the present invention can be adopted. In addition, in each figure, the same components are denoted by the same reference numerals.

[0042]

According to the waveform distortion determining apparatus and the waveform distortion determining method of the present invention, the waveform of the leading edge portion and the waveform of the trailing edge portion of the logic signal input to the logic element in the logic circuit are differentiated and rectified to obtain the negative polarity. By generating the sex pulse and counting the generated negative pulse to digitally determine whether the pulse is normal or abnormal, it is possible to always make a correct determination without missing a subtle step or the like.

Further, according to the waveform distortion determination device and the waveform distortion determination method of the present invention, the lower limit voltage (Vsl) is applied to the slice portion.
The waveform between the upper limit voltage (Vsh) and the upper limit voltage (Vsh) is cut, the cut waveform is amplified by the amplification unit to increase the gain, and determination is performed based on the waveform in which the leading edge portion and the trailing edge portion are enlarged. The presence or absence of a step and the presence or absence of a slight change in inclination can be detected, and the accuracy of determination can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a waveform distortion determination device according to the present invention.

FIG. 2 is a diagram showing a state transition of a waveform when a normal measured signal is input to the waveform distortion determination device shown in FIG.

3 is a diagram showing a state transition of a waveform when a signal under measurement having a step at a front edge portion is input to the waveform distortion determination device shown in FIG.

4 is a diagram showing a state transition of a waveform when a signal under measurement whose inclination of a front edge portion changes in the middle is input to the waveform distortion determination device shown in FIG.

5 is a determination table showing the determination result of the detection unit shown in FIG.

[Explanation of symbols]

1 probe part 2 Passage switch control section 3 passage switch section 4 slices 5 Amplifier 6 First differentiation part 7 First rectifier 8 Second differentiation part 9 Second rectifier 10 Detector

Claims (10)

(57) [Claims] 1. A waveform distortion judging device for judging distortion of a logic signal input to a logic element in a logic circuit, comprising: first differentiating means for differentiating the logic signal; and differentiating by the first differentiating means. A second differentiating means for further differentiating the waveform; and a judging means for judging whether the logic signal is normal or abnormal based on the output from the first differentiating means and the output from the second differentiating means. Waveform distortion determining device. 2. The waveform distortion determination device according to claim 1, wherein the determination means determines whether the logic signal is normal or abnormal by counting the number of pulses. 3. A pass switch means for cutting out a waveform of one cycle of the logic signal is provided, and the first differentiating means differentiates the waveform cut out by the pass switch means. Or the waveform distortion determination device according to 2. 4. Slicing means for slicing the waveform cut out by the passage switch means with an arbitrarily set lower limit voltage and upper limit voltage, and amplifying means for amplifying the waveform sliced by the slicing means. The waveform distortion determination device according to any one of claims 1 to 3, wherein the first differentiating means differentiates the waveform amplified by the amplifying means. 5. The lower limit voltage and the upper limit voltage when slicing by the slicing means are respectively set to threshold voltages for logic judgment of the logic element. Waveform distortion determination device. 6. A waveform distortion determination method for determining distortion of a logic signal input to a logic element in a logic circuit, wherein the logic signal is differentiated to generate a first differential waveform, and the first differential waveform is A waveform distortion determination method, which further differentiates to generate a second differential waveform, and determines whether the logic signal is normal or abnormal based on the first differential waveform and the second differential waveform. 7. The waveform distortion determination method according to claim 6, wherein whether the logical signal is normal or abnormal is determined by counting the number of pulses of each of the first differential waveform and the second differential waveform. . 8. The waveform distortion determination method according to claim 6, wherein a waveform of one cycle of the logic signal is cut out, and the cut-out waveform is differentiated to generate the first differential waveform. . 9. The sliced waveform is sliced with an arbitrarily set lower limit voltage and upper limit voltage, the sliced waveform is amplified, and the amplified waveform is differentiated to generate the first differential waveform. The waveform distortion determination method according to any one of claims 6 to 8, characterized in that. 10. The waveform distortion according to claim 6, wherein the lower limit voltage and the upper limit voltage at the time of slicing are threshold voltages for logic determination of the logic element, respectively. Judgment method.