Patent ID: 7869327

Claim:
A phase error detecting device, comprising: a waveform shaping portion that receives a digital reproduced signal generated from an analog reproduced signal reproduced from an information recording medium and shapes a waveform of the digital reproduced signal; a maximum likelihood decoding portion that applies maximum likelihood decoding to the digital reproduced signal in the waveform shaped by the waveform shaping portion and generates a binarized signal indicating a result of the maximum likelihood decoding; a phase detection portion that detects a phase error on the basis of the digital reproduced signal in the waveform shaped by the waveform shaping portion and the binarized signal generated by the maximum likelihood decoding portion; and a synchronization detection portion that generates a reproduction clock signal using the phase error detected by the phase detection portion and brings the digital reproduced signal in synchronization with the reproduction clock signal that has been generated, wherein the phase detection portion extracts, during the maximum likelihood decoding, the phase error using state transition patterns having only a single zero cross point among differential metrics at a plurality of merging points at which a set of paths branched from a given state merges.