Patent ID: 6317472
Filing Date: 2001-11-13
Classification: H03M

Abstract:
A Viterbi decoder comprising:a branch metric calculator for calculating a similarity between an input codeword and a predetermined codeword which can be output from an encoder and outputting 2N branch metrics where N is the number of states;an add-compare-select (ACS) portion for performing an add-compare operation by receiving 2N branch metrics and N previous state metrics provided from the branch metric calculator, selecting a survival path showing an encoding sequence closest to that of the received codeword, and calculating N current state metrics;and a state metric memory for providing the N previous state metrics to the ACS unit or storing the N current state metrics generated by the ACS unit; whereinsaid ACS unit comprises M ACS units each of which perform N/M operations during N/M cycles whenever a codeword is input; andsaid state metric memory comprises:a memory including a memory bank for reading and writing a state metric of the first half among the N state metrics generated in said ACS unit, and two memory banks for alternately reading and writing the state metrics of the second half whenever a codeword is input;a counter for counting a preceding sequence of said cycles;a write address generator for generating a write address of said memory based on the count result of said counter; anda read address generator for generating a read address of said memory based on the count result of said counter.