PHASE LOCK LOOP CIRCUIT HAVING PHASE LOCK DETECTING FUNCTION AND METHOD FOR DETECTING PHASE LOCK THEREFOR

摘要

The lock detecting method for a phase-locked loop circuit and a phase locked loop circuit having a lock detecting function is disclosed. A phase-locked loop circuit comprises a lock detection circuit. Lock detecting circuit has a lock detecting the start signal generating circuit, a lock detection clock generation circuit, and the lock detection signal generation circuit. Receiving the lock detecting start signal generating circuit and generating an up signal, respectively by the phase / frequency detector and the down signal, when the pulse widths of the up signal or down signal reaches a predetermined value and generates a lock detecting start signal. Rock receives the detection signal and the up-down clock generation circuit receives a latch signal and generates a lock detecting signal based on the clock signal and the up-down signal. Lock detecting signal generating circuit generates a counting the number of receiving the lock detection starting signal from the lock detecting the start signal generation circuit receives a clock detection signal from the lock detecting lock clock generation circuit and a clock signal lock detecting lock detecting signal. ; A phase-locked loop circuit to determine the operating region of a phase locked loop circuit, may output a lock detecting signal after phase synchronization is made fully by using the characteristics of the operating area.