Method and apparatus for output data synchronization with system clock in DDR

摘要

A method and apparatus are provided for substantially reducing or eliminating the timing skew caused by delay elements in a delay locked loop. A method and apparatus are disclosed wherein a rising edge of a local timing signal is established and phase-locked to a rising edge of a system clock signal by delaying the system clock signal. A falling edge of the local timing signal is established and phase-locked to a falling edge of the system clock signal by further delaying only a portion of a signal representative of the delayed clock signal. By separately delaying different portions of the system clock signal and using the separately delayed portions to establish a local timing signal, a local timing signal may be established which is compensated for the varied effects of delay elements in a delay locked loop.