Method for detecting frequency of digital phase locked loop

摘要

A method for detecting frequency of a digital phase locked loop in an optical disc is provided, which includes the steps of (a) detecting an edge point of an input signal, (b) sampling a previous and following input signal on the basis of the detected edge point into predetermined frequency, (c) counting the number of reference clock signals between the detected edge point and a sample which is positioned previously, adding a count value and an interval of time corresponding to the count value to obtain a frequency count value at the edge point, and (e) comparing the obtained frequency count value with a predetermined reference value, to enhance the frequency according to the comparison result. The method can detect frequency having high resolution with only reference clock frequency without heightening frequency of a reference clock signal, to thereby enhance quality of data. The frequency having high resolution with only reference clock frequency without heightening frequency of a reference clock signal is detected, to thereby enhance quality of data. <IMAGE>