| 摘要 |
PURPOSE:To set a maximum electric current which can flow to a semiconductor laser by a method wherein a resistor is inserted between the collector of a first transistor constituting a V-I conversion circuit and the base of a second transistor constituting a current mirror circuit. CONSTITUTION:A resistor R6 is inserted between the collector of a first transistor Q1 constituting a V-I conversion circuit and the base of d second transistor Q2 constituting a current mirror circuit 3. The inserted resistor R6 limits a collector current when the first transistor Q1 has been saturated, and limits a maximum current value to drive a semiconductor laser 4. Because the maximum current value which can flow to the semiconductor laser 4 can be set in this manner, the V-I conversion efficiency is not changed. |
