| 摘要 |
<P>PROBLEM TO BE SOLVED: To remarkably improve the measuring accuracy of an oscillation frequency by converting the oscillation frequency of several hundreds of MHz or more into frequency dividing output of several MHz or less at a product testing time of a laser drive LSI and measuring the frequency, and to prevent a yield from being lowered. <P>SOLUTION: A semiconductor laser driving device includes an output current source, a control circuit for controlling the output current source in response to a voltage or current set from an exterior, a switching circuit for opening/closing the output of an output current source, an oscillation circuit 57a for generating a high-frequency signal for suppressing the noise of the output light of a semiconductor laser 15, a high-frequency signal superposing circuit 57b for superposing the output signal of the oscillation circuit on control current for controlling the amount of the output light of the semiconductor laser to the drive current, and test control circuits 73, 74, 75 for sensing that a superposing frequency set terminal 62 becomes a special input state (power source voltage input state) at testing time by frequency dividing the output signal of the oscillation circuit to output the frequency dividing signal to a superposing amplitude setting terminal 60. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
