| 摘要 |
PROBLEM TO BE SOLVED: To provide a light-receiving amplifier circuit which does not prevent a high-speed response of an AC characteristic of a light-receiving element, and an optical pickup element provided with the same. SOLUTION: This light-receiving amplifier circuit consists of a first stage amplifier comprising an amplifier A1 for converting a current signal input from a photodiode PD into a voltage, and an amplifier A2 for reference; a differential amplifier A3 for amplifying the output difference of the first stage amplifier, and outputting two currents; a logarithmic conversion circuit A4 for applying logarithmic compression to the two currents outputted from this A3 and outputting two voltage signals; and a differential amplifier A5 for applying inverse logarithmic conversion to the two voltage signals output from this A4, and further outputting two voltage signals. A ratio of currents applied to each of the differential amplifiers A3 and A5 is varied by changing an externally attached resistor REXT, thereby adjusting sensitivity. COPYRIGHT: (C)2005,JPO&NCIPI
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