JP5291657B2 - Inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method.

  The test apparatus includes a number of DA converters. The test apparatus inspects the linearity of the DA converter provided therein during calibration. The test device outputs the output signal corresponding to one data from the DA converter to be inspected multiple times for the purpose of accurately inspecting the linearity of the DA converter, and calculates the average value of the levels of the plurality of output signals. inspect. Such an inspection mode is called, for example, an average mode.

  The test apparatus causes the sample apparatus to sample the output signal of the DA converter in the inspection of the DA converter in the average mode. At the same time, the test apparatus supplies a trigger signal designating the averaging period to the sample apparatus, and averages and outputs the value of the output signal sampled during the averaging period.

  The test apparatus sets the number of samples (average number of samples) to be averaged by the sample apparatus by changing the averaging period. As an example, the test apparatus can set the average number of samples such as once, twice, four times, eight times, and so on. As an example, the test apparatus performs an inspection of the DA converter in the average mode for each set average number of samples.

  Here, the trigger signal is transmitted together with the output signal of the DA converter, and is not synchronized with the sampling clock of the sample device. Therefore, the start timing or end timing of the averaging period specified by the trigger signal may almost coincide with the sampling clock timing. In such a case, the averaging process becomes unstable, and the sample device performs an average for the number of samples smaller than the average number of samples assumed in advance, or an average for the number of samples larger than the average number of samples assumed in advance. There is a possibility to go.

  Therefore, it is desirable that the test apparatus confirms whether the signal output from the DA converter is correctly averaged by the average number of samples specified by the sample apparatus prior to the inspection of the DA converter in the average mode.

  In order to solve the above-described problem, in the first aspect of the present invention, there is provided an inspection apparatus for inspecting a sample apparatus that averages and outputs a value of a signal under measurement for each trigger signal for a specified averaging period. A first signal that monotonically increases or decreases is supplied to the sample device, and a second signal that monotonically increases or decreases by a different type of curve from the first signal is supplied to the sample device; A trigger supply section for supplying a trigger signal to the sample device at each of a predetermined timing of one signal and a predetermined timing of the second signal; and the first output from the sample device in response to the trigger signal Based on the average value of one signal and the average value of the second signal, the number of samples in which the sample device averages the signal under measurement corresponds to the averaging period. Inspection apparatus comprising a determining unit, a whether the number of samples was, and to provide an inspection method.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

1 shows a configuration of a test apparatus 10 according to the present embodiment. An example of a signal under measurement, a trigger signal, and a sampling clock when the DA converter is inspected in the average mode in calibration is shown. An example of the first signal, the second signal, and the trigger signal that the inspection apparatus 30 supplies to the sample apparatus 20 is shown. An example of the average value of the first signal and the average value of the second signal measured by the inspection apparatus 30 and the predicted value of the average value of the second signal predicted from the average value of the first signal are shown. An example of the processing flow of the test | inspection apparatus 30 which concerns on this embodiment is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration of a test apparatus 10 according to the present embodiment. The test apparatus 10 tests a device under test. The test apparatus 10 includes at least one DA converter that outputs an analog signal. Each of the at least one DA converter sets a voltage on a member in the test apparatus 10 as an example.

  Further, the test apparatus 10 includes a sample device 20 and an inspection device 30. The sample device 20 samples the signal under measurement output from the DA converter inside the test device 10 during calibration. At the same time, the sample device 20 inputs a trigger signal that specifies an averaging period indicating an averaging period, and averages and outputs the value of the signal under measurement for each trigger signal for the specified averaging period. To do.

  The sample device 20 includes an ADC 12 and an averaging unit 14 as an example. The ADC 12 samples the signal under measurement for each sampling clock and outputs data representing the value of the sampled signal under measurement. The averaging unit 14 averages and outputs the value of the signal under measurement output from the ADC 12 during the averaging period specified by the trigger signal.

  In such a calibration, the sample device 20 outputs an output signal corresponding to one data from a DA converter provided in the test device 10 a plurality of times and inspects an average value of the levels of the plurality of output signals. Average mode can be executed. Thereby, the sample apparatus 20 can test | inspect accurately the DA converter with which the inside of the said test apparatus 10 is equipped.

  The inspection device 30 inspects the sample device 20 prior to the inspection of the DA converter in the average mode in calibration. More specifically, the inspection device 30 inspects whether or not the signal supplied from the outside can be correctly averaged with the average number of samples specified by the sample device 20.

  The inspection device 30 includes a timing generation unit 22, a signal supply unit 24, a trigger supply unit 26, a control unit 28, and a determination unit 32. As an example, the inspection device 30 may include a calibration board 50 that connects the signal supply unit 24 and the trigger supply unit 26 to the sample device 20 instead of the performance board on which the DUT is placed.

  The timing generation unit 22 generates a timing signal indicating the reference timing of signals supplied from the signal supply unit 24 and the trigger supply unit 26 to the sample device 20. The timing generation unit 22 supplies a timing signal to the signal supply unit 24 and the trigger supply unit 26.

  The signal supply unit 24 supplies the first signal that monotonously increases or decreases to the sample device 20 as the signal under measurement. Further, the signal supply unit 24 supplies a second signal that monotonously increases or decreases with a different type of curve from the first signal to the sample device 20 as a signal under measurement. For example, the signal supply unit 24 outputs a first signal and a second signal that start changing from the reference timing generated by the timing generation unit 22.

  The sample device 20 supplied with the first signal samples the first signal every sampling clock and sequentially outputs data representing the value of the first signal. The sample device 20 to which the second signal is supplied samples the second signal for each sampling clock and sequentially outputs data representing the value of the second signal.

  As an example, the signal supply unit 24 includes a waveform generation unit 42 and a DAC 44. The waveform generator 42 first outputs the waveform data of the first signal in synchronization with the reference timing generated by the timing generator 22, and then synchronizes with the reference timing generated by the timing generator 22. Outputs two-signal waveform data.

  The trigger supply unit 26 supplies a trigger signal that specifies an averaging period to the sample device 20 at each of a predetermined timing of the first signal and a predetermined timing of the second signal. As an example, the trigger supply unit 26 averages the sample device 20 to average a value for one sample, a value for two samples, a value for four samples, a value for eight samples, a value for sixteen samples,. Outputs a trigger signal that specifies the period.

  For example, the trigger supply unit 26 outputs a trigger signal having a pulse width corresponding to the averaging period. More specifically, the trigger supply unit 26 changes from the first logic (for example, L logic) to the second logic (for example, H logic) at the timing delayed from the reference timing by a set time, and then changes to the second logic. A pulse-like trigger signal that changes from the second logic to the first logic at the timing when the averaging period has elapsed is output together with each of the first signal and the second signal.

  The sample device 20 supplied with the trigger signal averages and outputs the values sampled during the averaging period specified by the trigger signal among the values of the plurality of first signals sampled at the timing of the sampling clock. . The sample device 20 supplied with the trigger signal averages and outputs the value sampled during the averaging period specified by the trigger signal among the values of the second signal sampled at the timing of the sampling clock. .

  The control unit 28 sets the waveform of the first signal and the waveform of the second signal in the signal supply unit 24. Thereby, the signal supply part 24 can output the 1st signal and 2nd signal of the set waveform.

  Further, the control unit 28 sets the averaging period in the trigger supply unit 26. As an example, the control unit 28 sets an averaging period in the trigger supply unit 26 corresponding to the number of samples in which the sample apparatus 20 should average the value of the signal under measurement in the average mode. Thereby, the trigger supply part 26 can supply the timing signal which designates the set averaging period to the sample apparatus 20 with each of the 1st signal and the 2nd signal.

  Based on the average value of the first signal and the average value of the second signal output from the sample device 20 according to the trigger signal, the determination unit 32 determines that the number of samples that the sample device 20 averages the signal under measurement is the trigger signal. It is determined whether the number of samples corresponds to the averaging period specified by. That is, when the determination unit 32 designates an averaging period during which the sample device 20 averages the values of N samples (N is an integer equal to or greater than 1), the sample device 20 sets the values of N samples of the signal under measurement. Or whether the values for samples other than N are averaged.

  For example, the determination unit 32 calculates a predicted value of the other average value based on one of the average value of the first signal and the average value of the second signal output from the sample device 20. Then, the determination unit 32 compares the calculated predicted value with the average value of the first signal and the average value of the second signal output from the sample device 20, so that the sample device 20 receives the average value. It is determined whether or not the number of samples for averaging the measurement signal is the number of samples corresponding to the averaging period.

  FIG. 2 shows an example of a signal under measurement, a trigger signal, and a sampling clock when the DA converter is inspected in the average mode during calibration. As an example, the test apparatus 10 inspects the linearity of the DA converter provided in the test apparatus 10 in the average mode in calibration.

  In this case, the test apparatus 10 causes the D / A converter to be inspected to output a signal under measurement whose level increases or decreases stepwise, for example, bit by bit. The sample device 20 samples the signal under measurement output from the DA converter to be inspected for each sampling clock, and acquires data representing the value of the sampled signal under measurement.

  Further, the test apparatus 10 outputs a trigger signal that specifies at least one averaging period for each level of the signal under measurement. The sample device 20 averages and outputs the value of the signal under measurement sampled during the averaging period for each averaging period specified by the trigger signal. Thereby, the sample apparatus 20 can measure the linearity of the DA converter to be inspected.

  Here, the sampling clock of the sample device 20 is not synchronized with the trigger signal. Therefore, the start timing or end timing of the averaging period specified by the trigger signal may almost coincide with the sampling clock timing. In such a case, the averaging operation of the sample device 20 becomes unstable, and an average for the number of samples smaller than the designated number of samples is performed, or an average for the number of samples larger than the designated number of samples is performed. End up. Further, there may be a case where averaging is performed with a number of samples different from the designated number of samples due to a defect in a circuit for averaging processing in the sample device 20 or the like.

  For example, as shown in FIGS. 2A and 2B, it is assumed that an averaging period for averaging values for four samples for each level of the signal under measurement is specified by the trigger signal. In this case, the sample device 20 averages and outputs the values for the four samples as shown in FIG.

  However, if the edge of the trigger signal coincides with the sampling clock, only a sampling clock of less than 4 is included during the averaging period. In this case, as shown in FIG. 2D, the sample device 20 averages and outputs the values of, for example, three samples.

  Therefore, the inspection device 30 inspects whether or not the sample device 20 samples in a good state. That is, the sample device 20 is inspected by determining whether or not the number of samples for which the sample device 20 averages the signal under measurement is the number of samples corresponding to the averaging period.

  FIG. 3 shows an example of the first signal, the second signal, and the trigger signal that the inspection apparatus 30 supplies to the sample apparatus 20. When inspecting the sample device 20, the signal supply unit 24 supplies the sample device 20 with a first signal that monotonously increases or decreases as a signal under measurement. For example, the signal supply unit 24 outputs a first signal that changes in a waveform corresponding to a linear function.

  In addition, the signal supply unit 24 supplies, to the sample device 20, a second signal that monotonously increases or decreases with a different type of curve from the first signal at a timing that does not overlap with the first signal. For example, the signal supply unit 24 outputs a second signal that changes in a waveform corresponding to a quadratic function.

  The signal supply unit 24 is different in the types of curves of the first signal and the second signal, and the first signal and the second signal both have a waveform corresponding to a function that monotonously increases or decreases monotonously. The first signal and the second signal may be output. For example, the signal supply unit 24 may output a signal corresponding to a linear function as one of the first signal and the second signal, and output a signal corresponding to a function other than the linear function as the other. The signal supply unit 24 may output a signal corresponding to a quadratic function as one of the first signal and the second signal, and may output a signal corresponding to a function other than the quadratic function as the other. Alternatively, a signal corresponding to a logarithmic function may be output as one of the first signal and the second signal, and a signal corresponding to a function other than the logarithmic function may be output as the other.

  Furthermore, the trigger supply unit 26 supplies a trigger signal to the sample device 20 together with the first signal. In addition, the trigger supply unit 26 supplies a trigger signal to the sample device 20 together with the second signal.

  For example, the trigger supply unit 26 outputs a timing signal for starting an averaging period from a timing (predetermined timing) delayed from a reference timing at which the first signal starts changing by a set time. For example, the trigger supply unit 26 outputs a timing signal for starting the averaging period from a timing (predetermined timing) delayed by the same set time from a reference timing at which the second signal starts to change.

  In response to the supply of the first signal and the trigger signal as described above, the sample device 20 outputs an average value of the values of the first signal sampled during the averaging period. Further, the sample device 20 outputs the average value of the values of the second signal sampled during the averaging period in response to the supply of the second signal and the trigger signal as described above.

  FIG. 4 shows an example of the average value of the first signal and the average value of the second signal measured by the sample device 20, and the predicted value of the average value of the second signal predicted from the average value of the first signal. .

  The phase relationship between the first signal and the trigger signal supplied together with the first signal is predetermined. The first signal is a predetermined function that monotonously increases or monotonously decreases. Therefore, if the number of samples from which the sample device 20 samples the signal during the averaging period is known, the average of the first signal at the reception point of the sample device 20 can be obtained from the average value of the first signal acquired by the sample device 20. The position (phase) of the conversion period can be calculated.

  The trigger signal output together with the first signal and the trigger signal output together with the second signal are output at the same timing with respect to the reference timing. The trigger signal output together with the first signal and the trigger signal output together with the second signal specify the same averaging period. The second signal is a predetermined function that monotonously increases or monotonously decreases.

  Therefore, if the number of samples from which the sample device 20 samples a signal during the averaging period is known, the sample device 20 should acquire the position of the averaging period with respect to the first signal at the reception point of the sample device 20. The average value of the two signals can be predicted. That is, the average value of the second signal to be acquired by the sample device 20 can be predicted from the average value of the first signal acquired by the sample device 20.

  Here, when the number of samples of the signal sampled by the sample device 20 during the averaging period matches the number of samples specified by the averaging period, the average value of the second signal calculated by the sample device 20 is predicted. The value and the average value of the second signal actually acquired by the sample device 20 coincide with each other. However, the first signal and the second signal are different types of curves. Therefore, when the number of samples in which the sample device 20 samples the signal during the averaging period does not match the number of samples specified by the averaging period, the predicted value of the average value of the second signal calculated by the sample device 20 And the average value of the second signal actually acquired by the sample device 20 does not match.

  For example, if the first signal is a linear function that increases and the second signal is a quadratic function that increases and the sampling device 20 is assumed to average two sample points during the averaging period, the sampling device When 20 actually averages only the value for one sample, as shown in FIG. 4, the actual average value of the second signal is lower than the predicted value of the average value of the second signal.

  Therefore, the determination unit 32 of the inspection apparatus 30 executes the determination process as follows. That is, the determination unit 32 acquires an average value of the first signals sampled by the sample device 20. Subsequently, the determination unit 32 calculates a predicted value of the average value of the second signal based on the average value of the first signal output from the sample device 20. Subsequently, the determination unit 32 acquires an average value of the second signals measured by the sample device 20.

  The determination unit 32 compares the predicted value with the other average value output from the sample device 20, and the number of samples that the sample device 20 averages the signal under measurement is the number of samples corresponding to the averaging period. It is determined whether or not. For example, the determination unit 32 determines whether or not the difference between the predicted value and the average value output from the sample device 20 is within a predetermined range. Thereby, the inspection apparatus 30 can inspect whether the sample apparatus 20 is averaging the signal under measurement with the number of samples corresponding to the averaging period specified by the trigger signal.

  The determination unit 32 calculates a predicted value of the average value of the first signal based on the average value of the second signal, and compares the predicted value of the average value of the first signal with the actual average value of the first signal. May be. In the sample device 20, the averaging period may be set separately from the trigger signal, instead of specifying the averaging period by the trigger signal. In this case, the sample device 20 is designated by the trigger signal as the timing for starting the averaging. Moreover, the sample apparatus 20 may specify the number of samples to be averaged as the averaging period.

  FIG. 5 shows an example of a processing flow of the inspection apparatus 30 according to the present embodiment. The inspection device 30 executes the processing from step S12 to step S18 for each number of samples (average number of samples) for which the sample device 20 averages the signal (loop processing between S11 and S19). As an example, the inspection apparatus 30 performs the processing from step S12 to step S18 for each average number of samples such as 1, 2, 4, 8, 16,.

  First, the control unit 28 of the inspection apparatus 30 sets an averaging period based on the average number of samples and the period of the sampling clock given to the sample apparatus 20 (S12). As an example, the control unit 28 sets the start timing and the time width of the H logic period of the trigger signal.

  Subsequently, the signal supply unit 24 supplies the first signal to the sample device 20 and supplies the trigger signal to the sample device 20 (S13). Thereby, the sample device 20 can average the value of the first signal sampled during the averaging period specified by the trigger signal.

  Subsequently, the determination unit 32 acquires an average value of the first signal from the sample device 20 (S14). Subsequently, the determination unit 32 calculates a predicted value of the average value of the second signal based on the average value of the first signal (S15).

  Subsequently, the signal supply unit 24 supplies the second signal to the sample device 20 and supplies the trigger signal to the sample device 20 (S16). Thereby, the sample device 20 can average the value of the second signal sampled during the averaging period specified by the trigger signal.

  Subsequently, the determination unit 32 acquires the average value of the second signal from the sample device 20 (S17). Subsequently, the determination unit 32 compares the predicted value of the average value of the second signal with the actual average value of the second signal, and the number of samples in which the sample device 20 averages the signal under measurement is equal to the averaging period. It is determined whether or not the number of samples is assumed in advance according to. And the inspection apparatus 30 will complete | finish a process, if the process of the above step S12 to step S18 is complete | finished about all the average sample numbers (for example, sample numbers, such as 1, 2, 4, 8, 16, ...).

  For example, when the number of samples that the sample apparatus 20 averages the signal under measurement is not the number of samples assumed in advance, the control unit 28 shifts the start timing of the averaging period specified by the trigger signal, for example. The process may be executed again from step S12. As a result, the inspection apparatus 30 determines that if the number of samples averaged by the sample apparatus 20 is different from the assumed number of samples because the edge position of the trigger signal matches the position of the sampling clock, The number of samples for averaging can be set to the number of samples assumed in advance.

  Further, each time the control unit 28 sets the number of samples, the signal supply unit 24 fixes one waveform of the first signal or the second signal, and the amount of change decreases as the number of samples for setting the other waveform increases. You may change so that. As a result, the inspection apparatus 30 can calculate the predicted value and the actual value when the number of samples averaged by the sample apparatus 20 is different from the assumed number of samples even when the number of samples averaged by the sample apparatus 20 is small. The difference from the average value can be increased.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

10 test apparatus, 20 sample apparatus, 12 ADC, 14 averaging section, 30 inspection apparatus, 22 timing generation section, 24 signal supply section, 26 trigger supply section, 28 control section, 32 determination section, 42 waveform generation section, 44 DAC 50 calibration board

Claims (10)

An inspection apparatus for inspecting a sample apparatus that averages and outputs a value of a signal under measurement for a specified averaging period for each trigger signal,
A signal supply unit that supplies a first signal that monotonically increases or decreases to the sample device, and that supplies a second signal that monotonously increases or decreases with a different type of curve from the first signal to the sample device;
A trigger supply section for supplying a trigger signal to the sample device at each of a predetermined timing of the first signal and a predetermined timing of the second signal;
Based on the average value of the first signal and the average value of the second signal output from the sample device in response to the trigger signal, the number of samples by which the sample device averages the signal under measurement is the average value. A determination unit for determining whether the number of samples according to the period;
An inspection apparatus comprising: The inspection device according to claim 1, wherein the trigger supply unit supplies a trigger signal that specifies an averaging period to the sample device. The determination unit calculates a predicted value of the other average value based on one of the average value of the first signal and the average value of the second signal output from the sample device, and the predicted value and the sample device output 3. The comparison with the other average value is performed to determine whether or not the number of samples by which the sample device averages the signal under measurement is the number of samples according to the averaging period. Inspection equipment. The inspection apparatus according to claim 3, wherein the determination unit determines whether or not a difference between the predicted value and an average value output from the sample apparatus is within a predetermined range. The signal supply unit outputs a signal according to a linear function as one of the first signal and the second signal, and outputs a signal according to a function other than the linear function as the other. The inspection device described in 1. The signal supply unit outputs a signal according to a quadratic function as one of the first signal and the second signal, and outputs a signal according to a function other than the quadratic function as the other. The inspection device according to any one of the above. The signal supply unit outputs a signal according to a logarithmic function as one of the first signal and the second signal, and outputs a signal according to a function other than the logarithmic function as the other. The inspection device described in 1. A control unit for setting an averaging period in the trigger supply unit corresponding to the number of samples in which the value of the signal under measurement is to be averaged;
The trigger supply unit supplies a trigger signal having a pulse width corresponding to a set averaging period to the sample device,
8. The determination unit according to claim 1, wherein, for each set number of samples, the sample device determines whether the number of samples for averaging the signal under measurement is a set number of samples. Inspection device. Each time the control unit sets the number of samples, the signal supply unit fixes one waveform of the first signal or the second signal, and the amount of change increases as the number of samples for setting the other waveform decreases. The inspection apparatus according to claim 8. An inspection method for inspecting a sample device that averages and outputs a value of a signal under measurement for a specified averaging period for each trigger signal,
Supplying a first signal monotonically increasing or decreasing to the sample device, and supplying a second signal monotonically increasing or decreasing to the sample device with a different type of curve than the first signal;
Supplying a trigger signal to the sample device at each of a predetermined timing of the first signal and a predetermined timing of the second signal;
Based on the average value of the first signal and the average value of the second signal output from the sample device in response to the trigger signal, the number of samples by which the sample device averages the signal under measurement is the average value. An inspection method that determines whether the number of samples corresponds to a period.

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