| 摘要 |
PURPOSE:To vary the amplitude limiting characteristic by providing an operational amplifier which amplifies the difference between a comparison input and a reference input which is set variably by a reference input circuit. CONSTITUTION:An operational amplifier 15 is provided which amplifies the difference between the comparison input and the reference input set variably by a reference input circuit 14. Since the comparison input of the operational amplifier 15 whose reference input can be variably set is supplied from a signal input terminal 12 to a limiter circuit 11 through a switching transistor (TR) Q whose bias voltage is set variably by a bias circuit 13, the input applied to the signal input terminal 12 is amplified with a degree of amplification peculiar to the operational amplifier 15 when the switching TR Q is made conductive. An output corresponding to the reference input of the operational amplifier 15 is obtained when the TR Q is cut off; and thus, the switching TR Q and the operational amplifier 15 are combined simply to obtain the amplitude limiting characteristic of optional left drop for the signal input.
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