| 摘要 |
PURPOSE:To constitute a synchronous separating circuit and a clamp pulse generating circuit as an LSI and to reduce the size of hardware by separating a synchronizing signal digitally from a PCM signal obtained by converting a television signal from analog to digital, and thus obtaining clamp pulses. CONSTITUTION:The television signal inputted to an input terminal (a) is inputted to an A/D converter 4 through a capacitor C1 and an amplifier 3 and converted into an (n)-bit PCM signal. A synchronous separating circuit 5 separates the synchronizing signal from the PCM signal through digital processing. The synchronizing signal separated by the synchronous separating circuit 5 is inputted to the clamp pulse generating circuit 6, which generates clamp pulses in synchronism with the synchronizing signal. When the clamp pulses are outputted from the clamp pulse generating circuit 6, a switch circuit 1 is closed only while the clamp pulses are outputted, so that the television signal inputted to the amplifier 3 is clamped to the potential of a clamp level V0 corresponding to the output voltage of a reference voltage circuit 2.
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