| 摘要 |
An improved delay chain for use in a delay locked loop which provides smooth phase adjustment and high resolution. In a delay chain having a series of cascaded unit delay elements, the outputs of a pair of contiguous delay elements (N, N+1) are selected for input to a phase blender. A coarse delay adjustment is carried out by selecting the outputs of the next pair of contiguous delay elements (N+1, N+2) and thus affects only one of the phase blender inputs. The phase blender provides a fine delay adjustment by generating an output whose phase is a weighted combination of the inputs, the weights having an inverse relationship. A coarse delay adjustment which affects an input of the phase blender is carried out when the weighting of that input is zero. Fine-to-coarse hand-over problems which characterize known delay locked loops are thus avoided.
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