| 摘要 |
Disclosed is a delay locked loop (DLL) for use in a semiconductor memory device, which has the ability to reduce or eliminate a power supply noise, a random noise or other irregular noise. The DLL includes a controllable delay modification unit for delaying a clock signal fed thereto to produce a time-delayed signal, a comparator for comparing the time-delayed signal from the modification block and a reference signal, and determining an addition or subtraction of the time delay according to the compared result to produce a corresponding output signal, and a delay control unit for counting the number that the corresponding output signal is activated, and producing a signal for controlling the addition or the subtraction of the time delay to the modification unit, if the counted value satisfies a predetermined condition.
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