Testing apparatus and method which adjusts a phase difference between rising and falling signals output from a DUT

摘要

A test apparatus for testing a device under test includes a first timing comparator obtaining a device output signal output from the device under test at a timing designated by a first strobe signal, a second timing comparator obtaining the device output signal at a timing designated by a second strobe signal supplied later than the first strobe signal, a preceding edge judging circuit, when rising and falling signals are input at the same timing as the device output signal, judging which one of the rising and falling signals arrives at the first and second timing comparators at an earlier timing, a preceding edge detecting circuit adjusting a timing at which the first strobe signal is supplied so that the first timing comparator obtains, at a timing of a rising or falling edge, one of the rising and falling signals which is judged to arrive earlier, and a following edge detecting circuit adjusting a timing at which the second strobe signal is supplied so that the second timing comparator obtains, at a timing of a rising or falling edge, one of the rising and falling signals which is judged to arrive later.