Optical transmission circuit controlling input voltage amplitude of optical transmission circuit drive stage according to pulse current

摘要

An optical transmission circuit operable with low voltage is disclosed, by which a stable waveform independent of the pulse current or the input signal pattern is output, and degradation of the waveform due to capacitance generated in a common emitter in the drive stage of the light emitting element is prevented. The optical transmission circuit comprises a light emitting element drive circuit (12) for driving a light emitting element (5); a previous-stage circuit (11a) for supplying a pulse current via a emitter-follower circuit; and a pulse current control circuit (2), connected to current sources (3, 4) of the light emitting element drive circuit and the previous-stage circuit, for controlling these current sources so as to fix the output of the light emitting element drive circuit and to control the amplitude of the output voltage from the previous-stage circuit according to the pulse current.