| 摘要 |
PURPOSE:To correct a phase with high accuracy, by a method wherein the amplitude of a voltage wave form and the phase correction quantity becoming necessary corresponding to said amplitude are preliminarily stored with respect to each pin and the amplitude of an actual input signal is set to an address to read stored data. CONSTITUTION:A signal 1 wherein the voltage value corresponding to a logical level H is set to a digital value and a signal 2 wherein the voltage value corresponding to a logical level L is set to a digital value are inputted to an operator 5 to operate the difference between the signals 1, 2 and the digital values of the amplitude of a logical level signal is calculated. This amplitude value is set to an address and the phase corrction quantity corresponding thereto is stored in a skew correcting memory 6 as data. The amplitude of the signal actually inputted to the pin electronics of a tester is calculated as a digital value and this digital value is set to an address to read the data stored in the memory 6 and phase correction is applied to the input signal of a driver 8 on the basis of the read value by a skew correction circuit 7 to output the phase corrected signal to a pin. Therefore, even when there is variation in the amplitude of the signal of each pin, a phase can be corrected with high accuracy.
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