Jitter tolerance improvement by phase filtration in feed-foward data recovery systems

摘要

Over-sampled timing signal jitter tolerance is improved in a q-times over-sampled architecture by phase-sampling the timing signal to produce a plurality of input phase samples &phgr;_in, where &phgr;_in&egr;{&phgr;₁, &phgr;₂, . . . , &phgr;_q}. An output phase value &phgr;_out=&phgr;_in is initialized for each input sample &phgr;_in. A difference vector d_i is derived for each input sample &phgr;_in, where d_i=F_j(n,k). F denotes a vector operation, n is the number of input samples, k is a pre-defined threshold value, and j represents a filter order value. A predefined scaling coefficient a_i is applied to each difference vector d_i to produce a corresponding set of scaled difference vectors a_i d_i. The scaled difference vectors are summed: $\mathop{\mathrm{image}}$ d_j=\underset{i=1}{\overset{n}{\∑}}\⁢a_i\⁢d_i.$$;The output value &phgr;_out is incremented by 1 if d_jk; decremented by 1 if d_j−k; and maintained unchanged if −k≦d_j≦k. Finally, the output value &phgr;_out is selected to represent the input sample &phgr;_in.