DIGITAL HORIZONTAL SYNCHRONIZATION RECOVERY CIRCUIT

摘要

PURPOSE:To obtain a horizontal synchronizing recovery signal with less jitter by using phase information finner than the unit of a sampling clock as a phase correction signal so as to detect the horizontal synchronizing signal with high accuracy in forming the horizontal synchronizing recovery signal synchronously with the horizontal synchronizing detection signal. CONSTITUTION:A digital video signal DVS is fed to a synchronizing separator circuit 12 and an inter sampling clock phase detection circuit 13. The synchronizing separator circuit 12 separates a synchronizing signal to obtain a composite synchronizing signal CS. A horizontal synchronizing detection circuit 14 obtains a horizontal synchronizing detection signal HS from the signal CS. The phase detection circuit 13 detects the phase difference between the sampling clock phiS and the leading edge of the HS to obtain a phase correction signal CSDELTAtau. The signals HS and CSDELTAtau are fed to a horizon tal phase error detection circuit 15. The detection circuit 15 forms a phase locked loop together with a horizontal loop filter 16 and a digital controlled oscillator 17 so as to detect the oscillated output phase (prescribed phase of horizontal counter output) of the oscillator 17 and the phase of the horizontal synchronizing signal in the video signal with high accuracy thereby operating the prescribed phase of the horizontal synchronizing recovery signal to be locked accurately.