| 摘要 |
PURPOSE:To ease the clamping function, by dividing the video signal of an output terminal in a video amplifying circuit with two resistances and applying the divided signals to the base of a transistor for feedback. CONSTITUTION:A video wave detecting circuit 1, a clamping circuit 2, a video circuit 3 and a vertical oscillating circuit 4 are used. The video signal of an output terminal 10 of a clamping video amplifying circuit 6 is divided by the resistances 21 and 22 and applied to the base of a feedback transistor 11. In such a way, the clamping function is eased. As a result, the change of the collector- emitter voltage can always be reduced within the division ratio of the resistances 21 and 22 for transistors 8 and 9. Thus the output video signal is never set lower than a prescribed level. Furthermore the base impedance is sufficiently high since the transistor 11 is equal to an emitter follower circuit, and as a result the high band properties of the output video signal are never disturbed. |
