Error correction circuit and method

摘要

A circuit 202 for executing range shift-up/-down of pass metric values is provided as an additional circuit preceding to an ACS circuit 203 for adding and comparing branch metric computation values and preceding pass metric values and selecting the highest likelihood pass. It is thus possible to permit effective use of RAM bits by executing range shift-up and the accuracy of the effective bits of input data when it is necessary to expand the effective bits of the pass metric values, while executing range shift-down and increasing the accuracy of the input data when the effective bits of the pass metric values are not fully used.