US Patent 7123552 Wobble signal detecting circuit for optical disc system

A wobble signal detecting circuit for optical disc system includes at least a sample-and-hold circuit for carrying out sample-holding steps on each of first and second photoelectric signals, and a high range frequency limiting circuit for removing frequency components equal to, or higher than, a predetermined cut-off frequency from the first and second photoelectric signals. By selectively enabling either the sample-and-hold circuit or high range frequency limiting circuit, depending on recording conditions during the period of recording information into an optical information recording medium, noise components which may unduly affect wobble signals can be removed efficiently, irrespective of recording conditions.