| 摘要 |
PURPOSE:To measure voltage for a short time with limited electron beam irradiation by providing a voltage decision circuit for determining a suppression grid voltage at the coincidence point between a slice level and a secondary electronic current with an accuracy of n bits in a contactless type voltage measuring apparatus for measuring voltages at various parts of electronic components of an integrated circuit employing electron beam. CONSTITUTION:A max. suppression voltage max Es is entered as initial value for measurement into a register 15, a min. suppression voltage min Es into a register 16 and a slice level Isl obtained with a slice level decision circuit into a register 17. Then, a value of the registers 15 and 16 is subjected to a repeated cycle of an addition mean 18-D/A conversion 8- an electron beam irradiation 9-A/D conversion 10-comparison 19- register rewritings 20, 21, 15 and 16. Simultaneously with this action, a half of a difference is computed between the contents Es15 of the register 15 and the contents Es16 of the register 16 with an arithmetic unit 22. The results of the computation is '0'', only when the difference between the contents Es15 and Es16 is '1'. When a discriminator outputs a signal '1', it indicates the coincidence. By an output '1' of a discriminator 23, above-mentioned repetition is stopped and an output of an arithmetic unit 18 is produced as suppression voltage Esv or Eso to be determined. |
