Patent ID: 7228248

Claim:
A test apparatus testing a device under test, comprising: a timing generator for generating, based on an output signal from the device under test, a strobe signal having a predetermined phase difference for the output signal; a timing comparator for detecting a signal value of the output signal at the timing of the strobe signal; and a decider for comparing the signal value detected by said timing comparator with a previously given expected value and deciding the good or bad of the device under test, wherein said timing generator comprises: a PLL circuit for generating the strobe signal of which the timing is shifted according to a given delay control voltage; a variable delay circuit for delaying the strobe signal according to the predetermined phase difference of the strobe signal for the output signal, the variable delay circuit being provided divergently from a path connecting the PLL circuit and said timing comparator; and a first phase comparing unit for comparing a phase of the strobe signal output from the variable delay circuit and a phase of the output signal output from the device under test and supplying the delay control voltage according to the phase difference to the PLL circuit.