Test apparatus, calibration method, program, and recording medium

1. A test apparatus that tests a device under test, comprising:

a driver that outputs a signal to a transmission line that is to be connected to the device under test;

a comparator that compares a level of the signal transmitted on the transmission line to a set reference level;

a judging section that judges acceptability of the device under test based on a measurement result, obtained by the comparator, of a response signal from the device under test; and

a response characteristic detecting section that, with an end of the transmission line on the device under test side connected to a prescribed potential, sequentially outputs a rising waveform and a falling waveform from the driver, and that detects a difference between a response time of the comparator for the rising waveform and a response time of the comparator for the falling waveform, based on measurement results, obtained by the comparator, of the waveforms and corresponding reflected waveforms, wherein the response characteristic detecting section calculates a difference between output characteristics of the rising waveform and the falling waveform output from the driver, based on the measurement results from the comparator of the waveforms and the corresponding reflected waveforms, and corrects a difference between the response times of the comparator based on the difference between the output characteristics.

2. The test apparatus according to claim 1 , wherein

when detecting the difference between the response time of the comparator for the rising waveform and the response time of the comparator for the falling waveform, the end of the transmission line on the device under test side is grounded.

3. The test apparatus according to claim 2 , wherein

the response characteristic detecting section sequentially sets at least two reference levels for the comparator for each of the waveforms output by the driver and corresponding reflected waveforms.

4. The test apparatus according to claim 3 , wherein

the response characteristic detecting section calculates slopes of the waveforms and the corresponding reflected waveforms input to the comparator, based on the measurement results from the comparator.

5. The test apparatus according to claim 4 , wherein

the response characteristic detecting section detects the difference between the response time of the comparator for the rising waveform and the response time of the comparator for the falling waveform, based on a first measurement time and a second measurement time, and corrects the difference between the response times based on the slopes of the waveforms and the corresponding reflected waveforms input to the comparator,

the first measurement time is from when the comparator measures the rising waveform to when the comparator measures the reflected waveform of the rising waveform, and

the second measurement time is from when the comparator measures the falling waveform to when the comparator measures the reflected waveform of the falling waveform.

6. The test apparatus according to claim 5 , further comprising a response characteristic adjusting section that adjusts a response characteristic of the comparator based on the difference between the response times detected by the response characteristic detecting section.

7. The test apparatus according to claim 5 , wherein

the comparator compares a level of a waveform input to the comparator to the reference level, at timings of a strobe signal having a prescribed period, and

the response characteristic detecting section adjusts the reference level such that a timing at which the level of the waveform input to the comparator matches the reference level is substantially the same as the timing of the strobe signal.

8. A method for calibrating a test apparatus that tests a device under test, comprising:

providing the test apparatus with:

a driver that outputs a signal to a transmission line that is to be connected to the device under test;

a comparator that compares a level of the signal transmitted on the transmission line to a set reference level; and

a judging section that judges acceptability of the device under test based on a measurement result, obtained by the comparator, of a response signal from the device under test; and

when (i) sequentially outputting a rising waveform and a falling waveform from the driver, with an end of the transmission line on the device under test side connected to a prescribed potential, and detecting a difference between a response time of the comparator for the rising waveform and a response time of the comparator for the falling waveform, based on measurement results, obtained by the comparator, of the waveforms and corresponding reflected waveforms, (ii) calculating a difference between output characteristics of the rising waveform and the falling waveform output from the driver, based on the measurement results from the comparator of the waveforms and the corresponding reflected waveforms, and correcting a difference between the response times of the comparator based on the difference between the output characteristics.

9. A recording medium storing a program causing a computer to function as a calibration apparatus that calibrates a test apparatus for testing a device under test, wherein

the test apparatus includes:

a driver that outputs a signal to a transmission line that is to be connected to the device under test;

a comparator that compares a level of the signal transmitted on the transmission line to a set reference level; and

a judging section that judges acceptability of the device under test based on a measurement result, obtained by the comparator, of a response signal from the device under test,

the program causes the computer to function as a response characteristic detecting section that, with an end of the transmission line on the device under test side connected to a prescribed potential, sequentially outputs a rising waveform and a falling waveform from the driver, and that detects a difference between a response time of the comparator for the rising waveform and a response time of the comparator for the falling waveform, based on measurement results, obtained by the comparator, of the waveforms and corresponding reflected waveforms, and

the program causes the response characteristic detecting section to calculate a difference between output characteristics of the rising waveform and the falling waveform output from the driver, based on the measurement results from the comparator of the waveforms and the corresponding reflected waveforms, and to correct a difference between the response times of the comparator based on the difference between the output characteristics.