| 摘要 |
PURPOSE:To obtain a high-precision circuit which prevents natural drift, by controlling a sample hold SH circuit by the output of a D/A converter where the output characteristic rises hesitatingly. CONSTITUTION:When sampling command signal Sp is supplied to terminal 60, switch 31 is closed to hold the potential of the external signal in SH circuit 3, and the output signal is input to comparator 5. When signal Sp disappears, an analogue signal rising hesitatingly for the count number of the pulse signal is input to comparator 5, and A/D converter 11 rises until this analogue signal agrees with the SH value. When the analogue output and the SH value agree with each other, the output of comparator 5 becomes 1 to reset FF6, and gate 13 is closed to hold the output of converter 11 at a fixed value equal to the SH value. Simultaneously, switch 7 is closed by the Q' output of FF6, and the analogue signal of converter 11 held fixed is supplied to hold the potential of capacitor 32 fixed, thus preventing output drift. Since the output of converter 11 does not generate a void, it agrees with the SH value with a high precision. |
