| 摘要 |
PURPOSE:To eliminate a noise even if the amplitude of an input signal is increased by decreasing or increasing an amplification factor depending whether an output signal level of a variable amplifier circuit is lower or higher than a lower limit reference level and transmitting the result to a noise removing circuit. CONSTITUTION:The variable amplifier circuit 1 decreases the amplification when an upper limit comparison signal VUC reaches a 1st level and increases the amplification factor when a lower limit comparison signal VLC reaches a 2nd level to output an input signal V1 as an amplified signal VA. When the signal VA exceeds the holding signal level of a prescribed level characteristic, the noise removing circuit 2 transmits the result to the output terminal and when lower, the circuit 2 stops the transmission to remove noise. An upper limit comparator 4 compares the signal VA with the upper limit reference level and when the signal VA is higher than the upper limit reference level, the signal VUC is outputted. Moreover, a lower limit comparator 5 compares the signal VA with the lower limit reference level and when lower than the lower limit reference level, the circuit 5 outputs the signal VLC. As a result, the peak clamping characteristic acts on the noise at all times, the noise is removed, only the real signal component can be detected. |
