Patent ID: 7463084
Filing Date: 2008-12-09
Classification: G11B

Abstract:
1. A signal filtering device for suppressing the variation of a DC level of an input signal to generate an output signal, the input signal being received from an optical data storage medium during three periods (t A ,t B ), (t B ,t C ), (t C ,t D ), the period (t A ,t B ) corresponding to a data field of a previous sector in the optical data storage medium, the period (t B , t C ) corresponding to a header field of a current sector in the optical data storage medium, the period (t C ,t D ) corresponding to a data field of a current sector in the optical data storage medium, the DC level of the input signal in the period (t A ,t B ) being substantially the same as that in the period (t C ,t D ), the DC level of the input signal in the period (t A ,t B ) being different from that of the input signal in the period (t B ,t C ), said signal filtering device comprising: a control signal generator for generating a first control signal and a second control signal, the first control signal and the second control signal corresponding to the period (t a high-pass filter module with a cutoff frequency for filtering the input signal to generate the output signal, the cutoff frequency being determined according to the first and second control signals, and the cutoff frequency for the control period (t