| 摘要 |
PURPOSE:To decrease the deterioration of a waveform and the potential fluctuation of an output signal in a transient state by limiting the potential fluctuation in a clamping means by providing a potential limiting means to a required minimum value with respect to an output dynamic range. CONSTITUTION:A potential limiting means 22 consists of a transistor (TR) 10 and a constant voltage source 11 so as to limit the transient potential raising in the input signal to a prescribed voltage. That is, when the base potential of the TR 4 is going to be lower than a prescribed voltage V1', a charging current flows from the emitter of the TR 3 of the clamping means 21 to the capacitor 2 rapidly and the base voltage of the TR 4 is kept to V1'. When the base potential of the TR 4 is going to be higher than the potential V3' decided by the TR 10 and the constant current source 11 forming the means 22, the discharge current from the capacitor 2 flows quickly to the emitter of the TR 10 and the voltage does not reach higher than the V3'. Thus, the low potential side among the input signal is matched to the voltage V1', the transient raising of the potential is limited to the voltage V1' and the potential fluctuation of the output signal and waveform deterioration are reduced.
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