| 摘要 |
<p>PURPOSE: A delay locked loop using a bi-directional oscillator and a counter is provided in which a time delay unit capable of controlling time delay bi-directionally is configured of a ring oscillator and a counter, to remarkably reduce layout area while maintaining merits of a conventional linear bi-directional time delay unit. CONSTITUTION: A delay locked loop includes an input part(400) for generating an inner clock, and a controller(410) for receiving the inner clock to generate the first forward signal and the second backward signal having a pulse width corresponding to one cycle of a clock signal, the first backward signal and the second forward signal having the phase opposite to that of the first forward signal and the second backward signal, and the first and second start signals having a pulse width as much as time delay to be compensated. The delay locked loop further has a bi-directional oscillator(421) which controls time delay while ring-oscillating in the first and second directions in response to the second forward signal, the second backward signal and the second start signal, and a counter for receiving a forward loop signal rotated in the first direction and a backward loop signal rotated in the second direction to count the number of rotations to compare the number of times of counting of the forward loop signal with that of the backward loop signal. The delay locked loop also has an output unit for adding up the outputs of the bi-directional oscillator and the counter to generate a final inner clock signal.</p> |
