AMPLIFIER CIRCUIT, LASER DRIVE CIRCUIT AND SEMICONDUCTOR LASER DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an amplifier circuit, a laser drive circuit and a laser drive device in which increase in the Gd of a transistor can be compensated. SOLUTION: An amplifier circuit 40 is provided with an input 6, a circuit stage 40a and a circuit stage 40b. The circuit stage 40a generates mutually different common mode signals in nodes 14a and 14b from a signal received from the input 6. The circuit stage 40b is provided with serial transistors 50a and 50b for receiving the respective common mode signals from the circuit stage 40a, and a current source 52 connected to these transistors. The common mode signal from the stage 50a is applied to the serially connected transistors 50a and 50b of the circuit stage 40b. Therefore, the voltage applied between a source and drain per transistor can be reduced, and these transistors respond to the respective common mode signals received by gates. Thus, circuit operation is realized within a comparatively small voltage range of Gd.