| 摘要 |
PURPOSE:To eliminate noise produced in a back porch period by selecting an output signal of a sample holding circuit for prescribed periods in the clamp pulse period of the back porch period and periods before and after the period. CONSTITUTION:The sample holding circuit 4 stores pedestal levels V41, V42... of an output video signal D at each time in the timing of a sample holding pulse P1 generated from a 1st pulse generator 7 in preceding over a clamp pulse C. A switch circuit 5 supply the pedestal levels V41, V42... stored in advance in the sample holding circuit 4 to an output terminal 6. Thus, a clean output video signal D not including noise E in a clamp pulse C in the back porch F is obtained at the output terminal 6.
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