| 摘要 |
PROBLEM TO BE SOLVED: To obtain an excellent reproduction characteristics even for a low reflection disk while dealing with high speed writing with large power in a light receiving amplifier circuit 20 of an optical disk recording and reproducing device. SOLUTION: The light receiving amplifier circuit 20 is composed of 2 stages, an initial stage amplifier and a subsequent stage amplifier. At the side of the initial stage amplifier 21, switching of a write mode and a reproduction mode is carried out by switching a parallel circuit having feedback capacitor Cf1w and a feedback resistor Rf1w, and a parallel circuit having feedback capacitor Cf1r and a feedback resistor Rf1r. At the side of the subsequent stage amplifier 23, parallel feedback resistors, Rf22, Rf23 are set, and the feedback resistor Rf23 is made to intervene in a feedback loop only when a regeneration of a high reflection disk reproduction by a switch transistor QSW. Thus, amplifier- gains adapting to each of writing, low reflection disk reproduction, and the high reflection disk reproduction can be set, and the excellent reproduction characteristics can be obtained even for the low reflection disk while dealing with the high speed writing with the large laser power. COPYRIGHT: (C)2003,JPO
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