LIGHT EMITTING ELEMENT DRIVING CIRCUIT AND OPTICAL TRANSMITTER

摘要

PROBLEM TO BE SOLVED: To provide a peak-detecting light emitting element driving circuit which can stably control signal light intensity and extinction ratio for either AC coupling or DC coupling, and to provide an optical transmitter.

SOLUTION: A light emitting element driving circuit 1 has a peak detector 61a for detecting a peak level of a voltage signal Smon corresponding to a low level of a signal light P and a bottom detector 62a for detecting a bottom level of a voltage signal Smon corresponding to the high level of the signal light P. A bias current source 4 adjusts a bias current Ibias in accordance with a difference between the peak level of the voltage signal Smon and a peak level reference voltage Vpk. A modulation current generator 3 adjusts a modulation current Imod in accordance with a difference between the bottom level of the voltage signal Smon and a bottom level reference voltage Vbt. In a bias current source 4, the modulation current generator 3 starts supply of the modulation current Imod in a prescribed time after supply of the bias current Ibias is started.

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