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

摘要

lock detection method of the 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 comprises a lock detection circuit and the entry window lock detecting signal generating circuit. Window lock detection circuit enters phase / frequency of the up signal or down signal generated by the detector at the front end of the delayed signal by a window and detects the state of the lock-up signal or down signal, and generates a lock detection signal entry window. Rock enable status is the detection signal generation circuit counts the input signal of the phase lock loop lock detection signal to generate an entry window lock detecting signal when continued for a predetermined time. After the phase locked loop circuit using the characteristics of the operation area of the phase-locked loop circuit consisting of phase synchronization is sufficiently lock may output a detection signal.