| 摘要 |
PROBLEM TO BE SOLVED: To effectively use the dynamic range of an ADC to its maximum by dynamically controlling the gain of an amplifier circuit in front of the ADC according to the level of an input signal. SOLUTION: A digital converting part 14 is provided with a comparator having a threshold that matches the input range of an ADC, and when an input signal from an amplifying part 12 exceeds the threshold, an over-range signal 70 is produced. A gain control part 60 calculates the frequency at which the signals 70 are output, and performs feedback control in which, when the frequency is great, the gain of the amplifying part 12 is reduced, whereas if it is small, the gain is increased, so that the range of the input signal amplified almost equals the dynamic range of the ADC at any time. |
