| 摘要 |
PURPOSE:To perform complete DC component reproduction, by sample-holding an input video signal with a clamp pulse to obtain, the output difference between the output and the input video signal, and fixing the input video signal to zero potential. CONSTITUTION:An output of a sample hold circuit 1 is applied to an inverting input terminal of an operational amplifier 2 via a resistor 3, an input video signal is voltage-divided with resistors 4 and 5, and applied to a non-inverting input terminal of the amplifier 2. Thus, even if a DC component is lost with a CR coupler or the like, a DC component differential voltage is outputted at the point of existing time of a clamp pulse at the circuit 1 and held until the next clamp pulse, and a signal fixing the input video signal to zero potential is outputted at a clamp pulse period with the difference voltage subtracted from the input video signal with a differential amplifier. |
