| 摘要 |
<p>PURPOSE:To set an optimum range even if an input signal is fluctuated, by resetting the gain of an amplifier based on a data obtained with the minimized amplifier gain. CONSTITUTION:A digital control circuit 7 transmits a signal SH to a switch circuit 3 and closes the switch circuit 3 once for a short time. The gain of the amplifier 5 is set minimum. An A/D converter 6 is operated and a data D converted into a digital signal is fetched to the digital control circuit 7 from the output. The digital control circuit 7 evaluates the data D and transmits a gain control signal GN in response to the value. The gain of the amplifier 5 is set optimum again. The A/D converter is operated while the switch circuit 3 is kept open, a voltage of a capacitor 4 as a voltage holding circuit is converted into a digital output signal.</p> |
