| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the influence of other powered-off driving circuits when operating one driving circuit and to secure pressure resistance of the powered-off driving circuits by connecting the outputs of a plurality of driving circuits in common. SOLUTION: A signal driving device is provided with: a first buffer circuit 12 which converts an optical signal input from a first photodetector into an electric signal and amplifies the converted signal; a second buffer circuit 14 which converts an optical signal input from a second photodetector into an electric signal and amplifies the converted signal; and a control circuit which activates either the first or second buffer circuits while the output stage of the other buffer circuit is stopped at high impedance. The influence of the stopped buffer circuit on the operating buffer circuit is eliminated, and the destruction of the output transistor in the buffer circuit of the stopped state is prevented. COPYRIGHT: (C)2007,JPO&INPIT
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