| 摘要 |
PURPOSE:To adjust DC level without increasing power loss in a circuit and to operate the amplifying part of a video signal at the optimum operating point by providing to constitute a power source voltage control part, a voltage setting part and a clamping part. CONSTITUTION:A video output circuit 31R, having an amplifying part 15R in which an input terminal 12R and two transistors 13 and 14 ar formed in cascade-connection and an output terminal 16R, is equipped with a power source voltage control part 33R which controls the supplying of power voltage to the amplifying part 15R and a clamping part 34R arranged between the output terminal of the amplifying part 15R and an output terminal 16R with accompanying a control input terminal 32R. The power source voltage control part 33R is connected between a power source line 17 and a load resistor 22, formed including a diode 35 which supplies a power source voltage Vcc obtained at the power source line 17 to the amplifying part 15R through the load resistor 22, a switch 37 and a diode 38, and the control terminal of the switch 37 is connected to the control input terminal 32R.
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