Wobble signal extracting circuit, method for extracting wobble signal, and optical disk unit

摘要

A wobble signal extracting circuit includes: a readout signal generating circuit generating an RF signal by adding first and second detection signals corresponding to reflected light from inside and outside a recording track; a first subtractor generating a push-pull signal by subtracting the first and second detection signals, respectively; a first analog-to-digital converter (ADC) converting the RF signal to digital; a second ADC converting the push-pull signal to digital; a residual RF component generating circuit generating a residual RF signal component equivalent to the RF signal component remaining in the digitized push-pull signal; and a second subtractor generating the wobble signal by subtracting the residual RF signal component from the digitized push-pull signal. The residual RF component generating circuit generates the residual RF signal component so that it may approach the remaining RF signal component based on correlation between the wobble signal and the digitized RF signal.