Method and a device for synchronizing a signal

摘要

A device synchronizes an internal signal with respect to a reference signal, each signal comprising pulses normally occurring at a rated frequency. The device uses a phase comparator to analyze the phase of the internal signal and the reference signal and produce one logic state if the phase of the internal signal is in advance of the phase of the reference signal and a second logic state otherwise. A programmable frequency divider divides an internal clock signal by a first number if the phase comparator signal produces the first logic state or by a second number if the phase comparator produces the second logic state. A multiplexer provides the programmable divider with either the first number or the second number depending on the logic state produced the phase comparator. The device also includes a storage element for sequentially storing a predetermined number of the latest logic states of the phase comparator. The device also includes circuitry for decrementing the first number when the latest stored logic states of the phase comparator have a single occurrence of the first logic state and for incrementing the second number when the latest stored logic states of the phase comparator have a single occurrence of the second state.