Patent ID: 7525898
Filing Date: 2009-04-28
Classification: G11B

Abstract:
1. An in-line circuit incorporated in an information playback apparatus, the in-line circuit canceling a difference between a DC offset of an RF signal that is reproduced from an address area of a track formed on an information storage medium, and a DC offset of an RF signal that is reproduced from a data area of the track, said in-line circuit comprising: a high-pass filter to which the RF signals reproduced from the information storage medium are input; a multi-bit AD converter which receives the output of the high-pass filter and has an output of at least 2 bits; and a lag lead filter to which the output of the AD converter is input, wherein said lag lead filter has a frequency characteristic of gain which changes from a lower-frequency-side flat characteristic to a primary integral characteristic at a first corner frequency, and changes from the primary integral characteristic to a higher-frequency-side flat characteristic at a second corner frequency, wherein said first corner frequency is a frequency at which a group delay characteristic of the signal after recovery of low-frequency components does not affect data reproduction, and wherein said second corner frequency is a frequency which is approximately equal to a cut-off frequency at which the frequency characteristic of the gain of the high-pass filter changes from the primary differential characteristic to the flat characteristic.