| 摘要 |
PROBLEM TO BE SOLVED: To provide a video preamplifier, which is composed of unit integrated circuits and can be commonly used for a cutoff control circuit in both systems of DC and AC coupling modes, and a cutoff control circuit for decreasing the number of external components except for the chip of a video preamplifier. SOLUTION: A switching part 304 is provided for accepting control data from the outside and generating a bus control signal toward an internal circuit or an external circuit corresponding to these control data. When operating a video amplifier 300 inside the cutoff control circuit in the DC coupling mode, the switching part 304 generates the bus control signal toward the internal circuit. When operating the video preamplifier 300 inside the cutoff control circuit in the AC coupling mode, on the other hand, the switching part 304 generates the bus control signal toward the external circuit. |
