A radix-4 soft-output Viterbi architecture

A new radix-4 soft-output Viterbi architecture is presented, which achieves higher data rates than prior radix-2 SOVA designs. The proposed architecture is also more hardware-efficient than a previously reported radix-4 SOVA architecture. New circuits are presented for the generation of path metric differences, the path comparison unit, and reliability update unit. The presented architecture is suitable for highspeed applications such as magnetic recording, where data rates are currently approaching 3 Gb/s.