| 摘要 |
PURPOSE:To lighten the burden of the Zener diode of a constant-voltage circuit, by connecting a compensating circuit for loaded fluctuating current to a generating circuit for laser diode bias current. CONSTITUTION:A laser diode 5 oscillates lights based on a signal current which arrives at a terminal (d), and a generating circuit 6 for laser diode bias current supplies a bias current IB to the laser diode 5. A bias current controlling voltage is impressed from a terminal (f). A controlling circuit 7 for loaded current compensation is provided in parallel to the generating circuit 6 for laser diode bias current. This controlling circuit 7 for loaded current compensation uses bias currents which are the same level as a DC-DC converter in the bias current generating circuit 6 and which have inversional characteristics. When the bias current IB changes as the threshold of the laser diode 5 changes due to temperature change, an electric current IX which compensates the changed quantity flows from the controlling circuit 7 for loaded current sompensation. |
