摘要 |
PROBLEM TO BE SOLVED: To provide a method for testing a semiconductor device capable of testing a semiconductor device outputting a reference clock DQS, used for data delivery, simultaneously to data reading, with high accuracy in a short period. SOLUTION: A timing for rising and falling of a reference clock outputted simultaneously with data read from a semiconductor device is read by plural signal reading circuit sampling acting with strobe pulse consisting of polyphase pulse having slight phase difference, and the timing for rising and falling of the reference clock is prescribed by a phase number of the polyphase pulse detecting a changing point, and the phase number is memorized by a memory 32. During testing, the data read from the semiconductor device is read by the timing determined by the phase number and it is judged whether there is a changing point or not with the timing so that quality of the semiconductor device is evaluated.
|