Patent ID: 7616726
Filing Date: 2009-11-10
Classification: G11B

Abstract:
1. An optical disk apparatus including an analog equalizer that receives a Radio Frequency (RF) signal from an optical head, and a Viterbi decoder that outputs a binary signal based on said RF signal, comprising: an Analog-to-Digital Converter (ADC) that converts said RF signal to a digital signal; a digital filter that receives said digital signal; and a digital Phase Locked Loop (PLL) circuit; wherein said PLL circuit comprising at least two phase detectors; a lock monitor; a selector connected to said at least two phase detectors and connected to said lock monitor, wherein said selector selects one of said at least two phase detectors according to an output of said lock monitor; a Low-Pass Filter (LPF) connected to said lock monitor and said selector; and a Voltage Controlled Oscillator (VCO) connected to said Low-Pass Filter (LPF); wherein one of said at least two phase detectors receives a signal that has passed through said digital filter, and another of said at least two phase detectors receives a signal that has not passed through said digital filter.