US Patent 7913153 Arithmetic circuit

An arithmetic circuit includes a NOR circuit for outputting 1-bit inverted logical OR sf from all of a first bit group x(6) to x(10) containing 0 or more high-order bit of a path metric value composed of a plurality of bits, an inverter for inverting each bit of a second bit group x(2) to x(5) and outputting a third bit group rs(0) to rs(3), an AND circuit for outputting a fourth bit group ns(0) to ns(3) that contain results of calculating a logical AND of sf and rs(0) to rs(3), and a CF output section for outputting a correction factor CF based on ns(0) to ns(3).