摘要:
Method and apparatus for recovering a clock and/or data from a serial data stream. A snapshot register and decoder using ring decoding decodes an N-bit data sample generated from an N-phase clock to determine a clock phase for extracting data. The ring decoding involves creating a first ring from the oversampled data by cyclically arranging the N-bit data sample in angle positions corresponding to clock phases. A second ring around the first one is calculated by EXNORing the samples of the first ring, subsequent rings are formed by ANDing the samples of the previous rings. The procedure stops when a 0-1-0 sequence appears on a ring. The optimum phase is determined as the phase of the 0-1-0 plus the ring index divided by two.