Apparatus and method of correcting offset

Abstract

An apparatus for correcting offset includes an optical pickup converting data recorded on an optical disc to an electrical signal; an AD converter quantizing a reproduction signal for each clock in synchronization with a bit period of the reproduction signal and sequentially outputting the signal as a quantized data column for each clock; an adder adding an offset adjustment amount to the quantized data column serving as an input signal; a Viterbi decoder performing Viterbi decoding on the signal after offset adjustment for binarization; and an offset correction value operating unit calculating the offset adjustment amount so that a value obtained by dividing a standard deviation of path metric difference between a survivor path and another path merged into the survivor path in the Viterbi decoder by an average of the path metric difference is minimized.