| 摘要 |
PURPOSE: To obtain a drive circuit which prevents overshoot or the like of an optical output waveform at an LC resonance frequency based on parasitic inductance and on parasitic capacitance by a method wherein a parallel resonant circuit which is composed of the parasitic inductance and the parasitic capacitance is connected to a laser diode to limit a current. CONSTITUTION: A laser diode LD comprises parasitic inductance L, and it is connected to.a coupling capacitor 3 and to a constant-current source CS. An FET Q2 comprises parasitic capacitance C, its drain is connected to an output- stage bias coil 2, and an FET Q4 as an amplification element whose impedance is changed by a control voltage β is connected. The parasitic inductance L and the parasitic capacitance C form an LC parallel resonance circuit. When the impedance of a power supply is disregarded, the LC parallel resonance circuit and the FET Q4 form a parallel connection. Thereby, when the resistance value of the FET Q4 is adjusted, it is possible to limit a current at an LC resonance frequency. |
