Patent ID: 7571376

Claim:
A Viterbi decoder comprising: a branch metric calculator which calculates a branch metric from a branch code passing each state on a trellis diagram and a predetermined input code; at least one adder/comparator/selector which adds the branch metric to a path metric of a previous state, detects a minimum value of result values from the addition as a path metric of a current state, and detects state transition values corresponding to a path from which the minimum value has been detected; a path metric memory which stores the path metric detected by the at least one adder/comparator/selector; a plurality of trace-back memories which sequentially store the state transition values detected by the at least one adder/comparator/selector; and a trace-back controller which, if the plurality of trace-back memories store the state transition values by a preset trace-back depth, executes a trace-back work in parallel in each of the plurality of trace-back memories.