| 摘要 |
PROBLEM TO BE SOLVED: To optimize the gain of a transimpedance type amplifier for a corresponding laser wavelength and the power of respective laser beams during recording and during reproduction while sharing a poststage amplifier. SOLUTION: The light receiver for an optical pickup comprises: two light receiving parts (photodetectors A and (a)) provided corresponding to two kinds of wavelengths; preamplifiers 22 and 32 for which the corresponding one of the light receiving parts is connected to a feedback input part; an output buffer 23 for amplifying voltage signals V1 outputted from the preamplifiers 22 and 32; resistors 24a-35b for feedback connectable between the feedback input part of the preamplifiers 22 and 32 and the output part of the output buffer; and switching parts 26 and 36 for switching and connecting one of the resistors 24a-35b for the feedback between the preamplifier 22 in an ON state between the preamplifiers 22 and 32 and the output buffer. The output current of the light receiving part connected to the preamplifier 22 in the ON state is converted to a voltage and amplified, and outputted as voltage signals V3. COPYRIGHT: (C)2008,JPO&INPIT
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