| 摘要 |
PURPOSE:To suppress saturation of the 1st part of a waveform by connecting an additional circuit comprising a diode and a variable resistor to a charge/ discharge circuit having a proper time constant and giving a constant voltage level set by the variable resistor via the diode when a hold voltage is a prescribed level or below so as not to bring the gain of an amplifier to a value or over. CONSTITUTION:A control voltage VC fed to a gain control terminal of an amplifier 1 is a larger voltage between a hold voltage VH of an output waveform and a constant voltage by a variable resistor VR and the control voltage VC fed to the amplifier 1 is held to a proper voltage or over by setting the variable resistor VR to a proper value. Thus, the gain of the amplifier 1 is suppressed to a proper value or below. Further, when a signal input is small, the controlvoltage VC of the amplifier 1 is made constant by the additional circuit 3 and the gain is constant until the constant voltage by the variable resistor VR shown in figure is exceeded. Thus, the gain of a small input is set optionally by adjusting the VR. |
