TIME-DISCRETE PHASE-LOCKED LOOP

摘要

A time-discrete phase-locked loop comprises a discrete time oscillator (DTO) which supplies a periodical oscillator signal (OS) representing oscillator values (OV) at corresponding clock instants (TC) of a clock signal (CLK). A position-determining circuit (P) generates a time-discrete synchronization instant (SI) representing a position of an analog synchronizing pulse (SP) of a video signal with sub-clock period accuracy. A phase detector (PD) determines a phase error (PE) between the discrete time oscillator signal (OS) and the synchronization instant (SI) by using the synchronization instant (SI), a value (OV1) of the discrete time oscillator signal (OS) at a clock instant (TC1) related to the synchronization instant (SI), and the slope of the oscillator signal (OS). A period of the oscillator signal (OS) depends on the phase error (PE). By using the slope of the oscillator signal (OS), the phase error (PE) is independent of this slope.