Calibration apparatus, calibration method, and testing apparatus

A calibration method for calibrating a jitter measuring circuit, the jitter measuring circuit comprising:

• a jitter signal generating section that generates a jitter signal of which duration of at least one of High logic or Low logic changes according to a jitter in an input signal;
• and
• an integrating section that charges and discharges a capacitor with a predetermined electric current according to the logical value of the jitter signal to integrate the jitter signal and outputs a jitter measuring signal with a level according to an amount of jitter in the input signal, and
• the calibration method comprising:
• making the integrating section output at least one of a predetermined charging current and a predetermined discharging current for charging and discharging the capacitor;
• measuring voltage variation of the capacitor in a state where the charging current or the discharging current is output to the integrating section;
• and
• computing gain of the integrating section based on the measured voltage variation.

A testing apparatus that tests a device under test, comprising:

• a jitter measuring circuit comprising:
• a jitter signal generating section that generates a jitter signal of which duration of at least one of High logic or Low logic changes according to a Jitter in a measured signal output from the device under test;
• and
• an integration section that charges and discharges a capacitor with a predetermined electric current according to the logical value of the jitter signal to integrate the jitter signal and outputs a jitter measuring signal with a level according to a jitter amount of the measured signal and a delay signal obtained by delaying the measured signal by a variable delay circuit;
• a deciding section that decides the good or bad of the device under test based on the jitter measuring signal;
• and
• a calibration apparatus that previously calibrates the jitter measuring circuit, and
• the calibration apparatus comprising:
• a current control section that makes the integrating section output at least one of a predetermined charging current and a predetermined discharging current for charging and discharging the capacitor;
• a voltage measuring section that measures voltage variation of the capacitor in a state where the charging current or the discharging current is output by the current control section;
• and
• a gain computing section that computes gain of the integrating section based on the voltage variation measured by the voltage measuring section.