| 摘要 |
PURPOSE:To contrive the improvement in yield by absorbing the variability included in an LD and an FET by introducing an FET for loop gain control in a light output stabilizing loop which forms an LD drive circuit, and modulating the operation characteristics by the output of an operation characteristic compensation circuit of said FET. CONSTITUTION:Adjustable resistors RV1 and RV2 commonly accept the level variation of the light output OUT sent from a light output stabilizing control part 14. Meanwhile, a resistor R2 accepts first offset voltage Vof1 and a resistor R5 accepts a second offset voltage Vof2. By presetting these offset voltages properly, the unevenness of the pinch-off voltages of an FET1 and an FET2 can be uniformed. Also, as those adjustable resistors RV1 and RV2 exist directly in a loop of a light output stabilizing loop, they modulate not only the unevenness of characteristics of the FETs, but also the comprehensive loop gain including the unevenness of threshold value or differential quantum efficiency of an LD itself. |
