Driver circuit and optical-transmission module

摘要

A driver circuit comprises a first differential-amplifier circuit having a pair of first transistors with emitters thereof connected to each other and a first resistor provided between an emitter connection point of the first transistors and a first power supply. Different electric potentials are applied to the bases of the pair of the first transistors to set a ratio of a current flowing through one of the pair of the first transistors to a current flowing through the other first transistor at about 1/100 or smaller. An amplitude of an output current is controlled by the higher of the electric potentials applied to the base of one of the first transistors.