| 摘要 |
PROBLEM TO BE SOLVED: To prevent reflection of high frequency by constituting a transmission line for high frequency signal to a light-emitting element to be formed from a microstrip line of a given characteristic impedance and impedance-matched at its termination. SOLUTION: A transmission line to a semiconductor laser in a wiring metal layer 16 is made a microstrip line 18, and it is connected to a microstrip line 5 of a circuit board 2 through a side surface electrode 7. Here, the microstirp line 18 is so designed that its characteristic impedance is equal to that of the microstrip line 5 on the circuit board, for impedance matching. By making the transmission lines 5 and 18 to the semiconductor laser LD microstrip lines, and further obtaining impedance matching at its termination with a chip resistance, impedance matching is obtained at the middle or the termination of a wiring, so that reflection of high frequency is prevented. |
