| 摘要 |
PROBLEM TO BE SOLVED: To provide a stable optical output control voltage with respect to power source voltage fluctuation without using any electric signal having the same mark rate as that of an input optical signal in a conventional manner. SOLUTION: The light/current and current/voltage conversion of an optical signal inputted to a photo-diode 109 is carried out, and a DC voltage in proportion to an amplitude of an optical signal is acquired by a peak detection circuit 101. An output voltage of the peak detection circuit 101 is compared with a collector voltage of a transistor 104 by a differential amplifier 102, and the difference voltage is amplified. The difference voltage is turned to zero when the amplitude of the optical signal reaches a desired value by controlling a resistance value of a resistance 108. Thus, it is possible to acquire an optical output control voltage in reverse proportion to an amplitude value of the optical signal at an output terminal voltage 110. COPYRIGHT: (C)2009,JPO&INPIT
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