FREQUENCY DETECTOR IN PHASE-LOCKED LOOP CIRCUIT, AND METHOD OF DETECTING FREQUENCY ERRORS

PROBLEM TO BE SOLVED: To provide a frequency detector which can detect frequency errors at a high speed in a phase-locked loop circuit, and to provide a method of detecting frequency errors. SOLUTION: The frequency detector comprises a runlength signal detecting unit which detects runlength signals from a sampled RF signal during a frequency detection cycle, based on the predicted distribution of predicted runlength signals; a counter unit, having at least one counter which counts the detected runlength signals during the frequency detection cycle; an edge counter which counts the passing edges of the sampled RF signal and controls the frequency detection cycle; and a frequency error generating unit which generates frequency errors during the frequency detection cycle by using the value counted by a counter contained in the counter unit and a predetermined reference value. COPYRIGHT: (C)2007,JPO&INPIT