| 摘要 |
PURPOSE:To calibrane automatically a variance of a DC discriminating point of a comparator by using an input waveform having a very low change so as to obtain the variance in the DC discriminating point with high sensitivity as a difference in the measuring time. CONSTITUTION:A computer 8 zeros an output (a) of a calibration digital-analog converter (DAC)5 in a circuit comprising a reference comparator 1 and a comparator 2 to be calibrated, inputs the same threshold voltage to all comparators so as to input the same voltage as that of outputs N1, N2 of operational amplifiers 3, 4. Then an output of a low speed slope waveform generator 6 is applied to all the comparators. In this case, the calibration is not executed yet, then a VOUT2 is in variance with a comparator output VOUT1 and the variance time (t) is obtained by a time difference measuring section 7. The correction value is obtained by the computer 8 from the time (t) and the slope of the input Vin, the output (a) is set to zero the time (t) and the voltage of the output N2 is calibrated.
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