| 摘要 |
PURPOSE:To calculate automatically the period of a sample IC which does not operate repeatedly with every trigger signals and operates with a basic clock, and to eliminate the need for manual operation and prevent an error in measurement of waveform, etc., by calculating the period and taking the measurement at the period. CONSTITUTION:An IC tester 1 drives the sample IC6 and further outputs a clock to a frequency dividing circuit 2. This circuit 2 outputs 1 as a frequency division rate to a phase shifter 3 in frequency division rate determining operation. The phase shifter 23 delays the phase of the trigger signal and outputs it to a blanking driver 4. An electron beam passed through a blanking plate 5, on the other hand, illuminates the sample to emit secondary electrodes, which are detected by a secondary electron detector 8 and converted into a voltage. Then, the voltage is applied to a correlator 10 to store digital data successively. Thus, the circuit 2 determines the frequency division rate with the signal of the frequency division rate determining circuit 12 and divides the frequency of the trigger signals to output the result to the phase shifter 3. At the same time, a switch SW is placed at a side B to output measurement data.
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