| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a laser diode drive circuit which can stabilize the operation by preventing breakdown of a transistor at the output stage. <P>SOLUTION: The laser diode drive circuit 1 comprises an offset addition circuit 5 which receives data signals D<SB POS="POST">1+</SB>, D<SB POS="POST">1-</SB>of positive phase and reverse phase and adds an offset voltage Vx between data signals D<SB POS="POST">2+</SB>, D<SB POS="POST">2-</SB>, a signal level determination circuit 7 which determines whether or not there is data based on the levels of the data signals D<SB POS="POST">1+</SB>, D<SB POS="POST">1-</SB>, a control circuit which controls the offset voltage Vx to change greatly when the determination is made that there is data by the signal level determination circuit 7 otherwise change the offset voltage Vx a little, a preamplifier 13 which performs differential amplification of the data signals D<SB POS="POST">2+</SB>, D<SB POS="POST">2-</SB>of positive phase and reverse phase, and a differential amplifier 15 which drives a LD 31 by receiving the output from the preamplifier 13 by differential pair transistors 23A and 23B. <P>COPYRIGHT: (C)2012,JPO&INPIT |
