| 摘要 |
For the purpose of achieving reproduction of data recorded in an optical disc, or the like, with high accuracy and hence increasing the recording density, a digital filter is provided at a position between an A/D converter and an adaptive equalizing filter and between the A/D converter and a PLL circuit. Basically, an analog filter has only a low pass function. In a learning period prior to reproduction, a controller section sets various tap coefficients in the digital filter to determine a tap coefficient such that a jitter value detected in the PLL circuit is minimum. In a reproduction operation, the determined tap coefficient is set in the digital filter to perform optimum pre-equalization, and as a result, reproduction of data is performed with high accuracy.
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