| 摘要 |
PROBLEM TO BE SOLVED: To operate an optical semiconductor element stably even at a slightly higher power source voltage than a forward direction operating voltage thereof, and output a switching current and voltage enough to drive the optical semiconductor element, by a method wherein a voltage pulse output from a predriver circuit is inputted to a base of a first transistor. SOLUTION: A pulse amplified by a predriver circuit 100 is inputted to an output circuit 200. The output circuit 200 is structured similarly to a Schmitt circuit. Specifically, an output pules signal voltage from the predriver circuit 100 is inputted to a base of a transistor Q6 connected to a resistor R1 as a collector load. A resistor Rf and a resistor Rb are connected in series to a contact of a collector of Q6 and the load resistor R1, and in order to input a signal to a base of a transistor Q7, the base of Q7 is connected to a node of the resistors Rf, Rb. Furthermore, in order to transmit a high frequency to the base of Q7, a capacity Cf is installed parallel to the resistor Rf.
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