| 摘要 |
PURPOSE:To dispense with a sample and hold circuit, and to reduce the number of capacitors and to stabilize a system by inputting the signal of a signal source to a signal processing circuit through a clamp capacitor, and making its output coincide with a reference signal. CONSTITUTION:The signal of the signal source 5 is inputted to the signal processing circuit 6 through the clamp capacitor 1. The output signal of the circuit 6 and the reference voltage E of a reference voltage source 4 are inputted to a current output relational amplifier 2 including a current stopping means. For instance, when the black level potential of the output signal of the circuit 4 is higher than the reference voltage E, the relational amplifier 2 absorbs the current and makes the capacitor 1 be discharged, during the period of a clamp pulse inputted from the terminal 3, and lowers the potential of the circuit 6 side, and corrects the output potential of the circuit 6. The output signal of the circuit 6 is obtained as a waveform, to which a video signal is superposed, while regarding the black level potential in the clamp period as the reference.
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