| 摘要 |
PURPOSE:To stabilize the conductive current to a semiconductor laser by a method wherein a semiconductor laser is connected to one collector terminal of a differential circuit; another collector terminal of a transistor for constant current supply is connected to a common emitter terminal; and a resistor is further series-connected to a base terminal of the transistor for constant current supply. CONSTITUTION:When a transistor 1 is made conductive by inputting a differential signal to a differential circuit comprising a pair of transistors 1, 2, a semiconductor layer 3 is supplied with power to emit light. The current flowing between collector and emitter of another transistor 5 is specified by base bias. A base current stabilizing resistor 10 is connected to a circuit between the connection of potential dividing resistor 8, 9 making base bias and a base terminal so that the base current of transistor 5 may be hardly fluctuated regardless of any fluctuation in the voltage impressed upon the potential dividing resistors 8, 9. Through these procedures, the collector-emitter current can be held at almost constant level to hold the current flowing in the semiconductor layer 3 at almost constant level. |
