Patent ID: 6304071
Filing Date: 2001-10-16
Classification: G11B,H03L,H04L

Abstract:
A phase detector, for determining an error value dependent on a relative phase between a local oscillator signal and a read signal, the phase detector comprising:means for comparing a first, a second, and a third actual sample value of said read signal to a plurality of thresholds to provide a first, a second, and a third ideal sample value respectively, wherein said first, said second, and said third actual sample values are determined at a sampling time, a preceding sampling time, and a twice preceding sampling time respectively relative to said local oscillator signal;means for delaying said second actual sample value, said second ideal sample value, and said third ideal sample value until said first sampling time;means for calculating a difference value corresponding to a difference between said second ideal sample value and said second actual sample valuemeans for calculating a first sense of change to said first ideal sample value from said second ideal sample value;means for calculating a second sense of change to said second ideal sample value from said third ideal sample value;means for calculating a gradient responsive to said first sense of change and said second sense of change; andmeans for calculating said error value responsive to said gradient and said difference value.