Signal generating apparatus and test apparatus

1. A signal generating apparatus comprising:

a DA converter that outputs an output signal corresponding to input data supplied thereto;

a comparing section that compares (i) a level of a signal output from an analog circuit that propagates the output signal to output a signal corresponding to the input data to (ii) a level of the signal output by the DA converter; and

a measuring section that measures a waveform of the signal output by the analog circuit based on a comparison result of the comparing section, wherein

the DA converter outputs a voltage corresponding to data supplied thereto,

the signal generating apparatus further comprises a sample/hold section that samples a voltage output by the DA converter and holds the sampled voltage, and

the measuring section (i) provides the DA converter with setting data to cause the DA converter to output a setting voltage corresponding to the setting data, (ii) causes the sample/hold section to sample the setting voltage, (iii) provides the analog circuit with the setting voltage held by the sample/hold section, and (iv) measures a settling waveform of the voltage of the signal output from the analog circuit, from when the setting voltage is provided to when the voltage stabilizes.

2. The signal generating apparatus according to claim 1 , wherein

during a holding period in which the sampled voltage is held, the measuring section (i) provides the DA converter with comparison data to cause the DA converter to output a comparison voltage corresponding to the comparison data, (ii) causes the comparing section to compare the voltage of the signal output by the analog circuit to the comparison voltage, and (iii) measures the settling waveform based on the comparison result of the comparing section.

3. The signal generating apparatus according to claim 2 , wherein

the sample/hold section includes:

a capacitor section that is provided between an output end of the sample/hold section and a reference potential; and

a switch that provides a connection between the DA converter and the output end of the sample/hold section during a sampling period in which the voltage output from the DA converter is sampled, and disconnects the DA converter from the output end of the sample/hold section during the holding period.

4. The signal generating apparatus according to claim 2 , wherein

at a predetermined measurement timing in the holding period, the measuring section causes the comparing section to compare the voltage of the signal output by the analog circuit to the comparison voltage, and

the measuring section detects the voltage of the signal output by the analog circuit based on the comparison result of the comparing section, and measures the settling waveform based on the detected voltage.

5. The signal generating apparatus according to claim 4 , wherein

the measuring section changes the comparison data according to rules of a binary search to detect the voltage of the signal output by the analog circuit.

6. The signal generating apparatus according to claim 2 , wherein

the measuring section repeatedly provides the DA converter with the same setting data,

for each of a plurality of cycles in which the same setting data is provided, the sample/hold section samples the voltage of the signal output by the DA converter and holds the sampled voltage, and

the measuring section (i) causes the DA converter to output the comparison voltage by supplying the DA converter with comparison data that differs for each of the plurality of cycles at a first measurement timing in the holding period of each cycle and (ii) detects the voltage of the signal output by the analog circuit at the first measurement timing based on comparison results acquired by the comparing section for the plurality of cycles.

7. The signal generating apparatus according to claim 2 , wherein

during the holding period, the measuring section (i) causes the DA converter to output a first comparison voltage by providing first comparison data thereto, (ii) causes the comparing section to compare the voltage of the signal output by the analog circuit to the first comparison voltage, (iii) detects a first change timing at which the comparison result of the comparing section changes, and (iv) measures the settling waveform based on the detected first change timing and the first comparison voltage.

8. The signal generating apparatus according to claim 7 , wherein

during the holding period, after the comparison result between the voltage of the signal output by the analog circuit and the first comparison voltage has changed, the measuring section (i) causes the DA converter to output a second comparison voltage by providing second comparison data thereto, (ii) causes the comparing section to compare the voltage of the signal output by the analog circuit to the second comparison voltage, (iii) detects a second change timing at which the comparison result of the comparing section changes, and (iv) measures the settling waveform further based on the detected second change timing and the second comparison voltage.

9. The signal generating apparatus according to claim 1 , wherein

the measuring section measures the waveform during calibration of the signal generating apparatus, and

the signal generating apparatus further comprises a correcting section that corrects the output signal from the DA converter based on the waveform measured by the measuring section.

10. The signal generating apparatus according to claim 9 , wherein

the correcting section compensates a component of the output signal from the DA converter that is attenuated by the analog circuit, according to a response characteristic of the analog circuit that is calculated based on the waveform measured by the measuring section.

11. The signal generating apparatus according to claim 1 , wherein

the analog circuit propagates the output voltage from the DA converter to an input end of a target circuit, and

the comparing section compares the voltage at the input end of the target circuit to the comparison voltage output by the DA converter.

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

a signal generating apparatus that generates a voltage provided to the device under test; and

a drive section that supplies the device under test with the voltage generated by the signal generating apparatus, wherein

the signal generating apparatus comprises:

a DA converter that outputs an output signal corresponding to input data supplied thereto;

a comparing section that compares (i) a level of a signal output from an analog circuit that propagates the output signal to output a signal corresponding to the input data to (ii) a level of the signal output by the DA converter; and

a measuring section that measures a waveform of the signal output by the analog circuit based on a comparison result of the comparing section.

13. The test apparatus according to claim 12 , wherein

the DA converter outputs a voltage corresponding to data supplied thereto,

the signal generating apparatus further comprises a sample/hold section that samples a voltage output by the DA converter and holds the sampled voltage, and

the measuring section (i) provides the DA converter with setting data to cause the DA converter to output a setting voltage corresponding to the setting data, (ii) causes the sample/hold section to sample the setting voltage, (iii) provides the analog circuit with the setting voltage held by the sample/hold section, and (iv) measures a settling waveform of the voltage of the signal output from the analog circuit, from when the setting voltage is provided to when the voltage stabilizes.

14. The test apparatus according to claim 13 , wherein

during a holding period in which the sampled voltage is held, the measuring section (i) provides the DA converter with comparison data to cause the DA converter to output a comparison voltage corresponding to the comparison data, (ii) causes the comparing section to compare the voltage of the signal output by the analog circuit to the comparison voltage, and (iii) measures the settling waveform based on the comparison result of the comparing section.

15. The test apparatus according to claim 14 , wherein

the sample/hold section includes:

a capacitor section that is provided between an output end of the sample/hold section and a reference potential; and

a switch that provides a connection between the DA converter and the output end of the sample/hold section during a sampling period in which the voltage output from the DA converter is sampled, and disconnects the DA converter from the output end of the sample/hold section during the holding period.

16. The test apparatus according to claim 14 , wherein

at a predetermined measurement timing in the holding period, the measuring section causes the comparing section to compare the voltage of the signal output by the analog circuit to the comparison voltage, and

the measuring section detects the voltage of the signal output by the analog circuit based on the comparison result of the comparing section, and measures the settling waveform based on the detected voltage.

17. The test apparatus according to claim 14 , wherein

the measuring section repeatedly provides the DA converter with the same setting data,

for each of a plurality of cycles in which the same setting data is provided, the sample/hold section samples the voltage of the signal output by the DA converter and holds the sampled voltage, and

the measuring section (i) causes the DA converter to output the comparison voltage by supplying the DA converter with comparison data that differs for each of the plurality of cycles at a first measurement timing in the holding period of each cycle and (ii) detects the voltage of the signal output by the analog circuit at the first measurement timing based on comparison results acquired by the comparing section for the plurality of cycles.

18. The test apparatus according to claim 14 , wherein

during the holding period, the measuring section (i) causes the DA converter to output a first comparison voltage by providing first comparison data thereto, (ii) causes the comparing section to compare the voltage of the signal output by the analog circuit to the first comparison voltage, (iii) detects a first change timing at which the comparison result of the comparing section changes, and (iv) measures the settling waveform based on the detected first change timing and the first comparison voltage, and

during the holding period, after the comparison result between the voltage of the signal output by the analog circuit and the first comparison voltage has changed, the measuring section (v) causes the DA converter to output a second comparison voltage by providing second comparison data thereto, (vi) causes the comparing section to compare the voltage of the signal output by the analog circuit to the second comparison voltage, (vii) detects a second change timing at which the comparison result of the comparing section changes, and (viii) measures the settling waveform further based on the detected second change timing and the second comparison voltage.

19. The test apparatus according to claim 13 , wherein

the measuring section measures the waveform during calibration of the signal generating apparatus, and

the signal generating apparatus further comprises a correcting section that compensates a component of the output signal from the DA converter that is attenuated by the analog circuit, according to a response characteristic of the analog circuit that is calculated based on the waveform measured by the measuring section.

20. A signal generating apparatus comprising:

a DA converter that outputs an output signal corresponding to input data supplied thereto;

a comparing section that compares (i) a level of a signal output from an analog circuit that propagates the output signal to output a signal corresponding to the input data to (ii) a level of the signal output by the DA converter; and

a measuring section that measures a waveform of the signal output by the analog circuit based on a comparison result of the comparing section.