| 摘要 |
PURPOSE:To correct an output of an A/D converter and to obtain an accurate converting output even if the polarity of an input signal is changed, by obtaining a ratio between a negative and a positive reference voltage and correcting an output of a counter with this ratio. CONSTITUTION:A discharge time T1 of the positive reference voltage 3 is obtained by giving charge for a time T0 with the negative reference voltage 2, and similarly a discharge time T2 with mT0 of charging time, a time T3 charged with the positive reference voltage 3 for the time T0, discharged with the negative reference voltage 2,and a discharge time T4 taking the charge time as the mT0 are obtained respectively and [(T4-T3)/(T2-T1)]<1/2>=ratio alpha is obtained. Then, an accurate converting utput is obtained by giving a digital output when the input signal at an input terminal 11 is negative and by giving an output after multiplying the ratio alpha to the output when the input signal is positive. |
