| 摘要 |
A clipper includes an amplifier having a non-inverting input node (11), an inverting input node (13), and an output node (57). A feedback transistor (Q3) has its base connected to the amplifier output node and its collector connected to the non-inverting input node (11) for providing unilaterally conductive degenerative current feedback between the output node (57) and the non-inverting input node (11). A resistor (R1) is connected between the non-inverting input node and an input terminal for conducting a current supplied via the collector-to-emitter path of the feedback transistor (Q3) which is proportional to the amplitude of an unclipped portion of the signal applied between the input terminal and the inverting input node (11). When a reference potential is applied to the inverting input node (13) and an AC input signal varying about the reference potential is applied to the input terminal, the stage functions as a negative half-wave rectifier. When the reference potential is applied to the input terminal and the AC input signal is applied to the inverting input node (13), the stage functions as a positive half-wave rectifier. Two rectifying stages can be interconnected with the collectors of the feedback transistors connected in common to form a full-wave rectifier. The output of the full-wave rectifier can be used to control the gain of an amplifying means producing the AC signal being detected. |
