| 摘要 |
PROBLEM TO BE SOLVED: To improve the quality of a digital signal without causing the increase of development cost and power consumption.SOLUTION: An ADC 230 included in a signal conversion circuit 20 samples an analog signal 303 which represents the intensity of a laser beam 302 emitted from a laser source 110 driven by a current superimposed with a high-frequency signal 305, and reflected by an optical disk 2 by means of a clock signal 306 whose frequency is substantially the same as that of the high-frequency signal 305 and converts the sampled analog signal into a digital signal 304. An LPF 220 provided in a stage preceding the ADC 230 passes a band component of not higher than a predetermined frequency of the analog signal 303. At this time, the frequency of the clock signal 306 is set to be higher than the predetermined frequency. |
