ENCODING OF DATA WORDS USING THREE OR MORE SIGNAL LEVELS

摘要

A data processing circuit comprises an encoder circuit for encoding a data word, wherein each digit may have any one of three or more digit values. The data word is encoded so that digit counts in the data word satisfy predetermined criteria (the digit counts are counts of the numbers of the digits in the encoded data word that assume respective digit values). The encoder defines at least two digit maps, each digit map defining assignments of each of the available digit values to a respective different output digit value. The encoder selects at least two groups of digits within the input data word. Each group is associated with a respective one of the digit maps, the groups being selected so that when each digit map has been applied selectively to the digits from its associated group, digit counts of the number of times respective digit values occur in the data word will satisfy predetermined criteria. A data signal is generated that represents the input data word by information that identifies the selected groups and an output data word obtained by mapping the digits of each group in the input data word according to the digit map for that group.