| 摘要 |
PROBLEM TO BE SOLVED: To provide a laser driver which does not give an influence of noise to a differential signal to be input. SOLUTION: The laser driver 1 is provided with an input buffer 10 to which a differential signal is input; a differential amplifier 20 which amplifies a difference of a differential signal output from the input buffer 10 to convert the differential signal into a positive phase output signal and an opposite phase output signal by current; a modulation current source 30 which supplies constant current to the differential amplifier 20, and sets a differential element between the positive phase output signal and the opposite output signal of the differential amplifier 20; a vias current source 50 which supplies bias current to a semiconductor laser 99; and an input signal monitor circuit 60 which turns on current of the modulation current source 30 or the bias current source 50 when the differential signal is input, and turns off current of the modulation current source 30 or the bias current source 50 when the differential signal is not input. COPYRIGHT: (C)2008,JPO&INPIT
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