Delay locked loop circuit

摘要

A delay locked loop circuit, comprising: first delay means for receiving an external clock signal to generate a delay clock signal; first oscillation means for generating a first pulse signal; second oscillation means for generating a second pulse signal; phase detection means for receiving the external clock signal and an internal clock signal and generating a phase detection signal; second delay means for delaying the delay clock signal by one period of the first pulse signal of the first oscillation means to generate a first plurality of clock signals; third delay means for delaying the delay clock signal by one period of the second pulse signal of the second oscillation means to generate a second plurality of clock signals; selection means for selecting a pair of clock signals having the same delay time from the first plurality of clock signals and the second plurality of clock signals; logic means for combining the pair of clock signals selected from the selection means to generate the internal clock signal; and control means for generating control signals for controlling the first delay means, the first and second oscillation means and the selection means and a reset signal for resetting the first and second delay means in accordance with the phase detection signal from the detection means.