US Patent 7148733 Variable delay circuit with faster delay data update

Delays induced to leading and trailing edges of an input pulse train are updated faster than before. First and second delay paths receive delay data for inducing delays to leading edges and/or trailing edges of an input pulse train. An OR circuit combines the outputs of the delay paths. First and second gates receive the input pulse train and selectively provide the input pulse train to the first and second delay paths independent of the edge position of the input pulse train. A delay time setup circuit generates a CTRL signal for controlling the first and second gates and the loading of the delay data to the first and second delay path. The CTRL signal causes the gates to selectively switch the input pulse train from one delay path to another while the delay data is selectively loaded in the delay path not receiving the input pulse train.