| 摘要 |
PURPOSE:To obtain a circuit which can prevent surge currents causing the breakdown of an element in a semiconductor laser by connecting an inductor to an input terminal for a constant-current circuit and connecting a capacitor between a control terminal and an output terminal. CONSTITUTION:A DC bypass circuit 5 is formed in constitution in which a capacitor 53 is connected between a base and an emitter of a transistor 51 constituting a constant-current circuit, an inductor 54 is connected to a collector and a control signal (s) from a comparison circuit 3 is inputted to the base of the transistor 51 through an operational amplifier 52. The capacitor 53 and the inductor 54 prevent a flowing of surge currents through a semiconductor laser 1 on the ON-OFF of a power supply at that time, and the breakdown of an element can be obviated by the operation of the prevention. Accordingly, the DC bias circuit is very effective when it is applied to an APC circuit. |
