Register controlled delay locked loop with reduced delay locking time

摘要

A register controlled delay locked loop includes a clock generation unit which receives an external clock signal for generating a source clock signal by buffering the external clock signal and for generating a delay monitoring clock signal and a reference clock signal by diving the source clock signal by a natural number; a delay line control unit which receives the reference clock signal and a feed-backed clock signal for generating a normal shift control signal and an acceleration shift control signal based on a result of a comparison between phases of the reference clock signal and the feed-backed clock signal; a delay line unit which receives the source clock signal for generating a delay locked clock signal by delaying the source clock signal according to a delay amount of the delay line unit determined by the normal shift control signal and the acceleration shift control signal; and a delay model unit for estimating a delay amount generated while the external clock signal is passed to a data output pin to generate the feed-backed clock signal, wherein an absolute delay amount based on the acceleration shift control signal is larger than that based on the normal shift control signal.