| 摘要 |
PURPOSE:To provide a current source type of semiconductor light emitting drive circuit capable of carring out high-speed operation. CONSTITUTION:A current 181 for operating a laser diode 1a is supplied from the power source 5 connected in series to a laser diode 1a. A differential switch circuit composed of a load resistor 4, transistors Q1 and Q2, and a current source 6 is connected in parallel with the laser diode 1a. The current flowing to the laser diode 1a is changed by turning on or turning off the transistor Q2 by the signal inputted from input terminals 2 and 3. Hereby, the transistor Q2 operates in the range narrow in active region, whereby the laser diode 1a can be driven at high speed. |
