CONSTANT MULTIPLIER, DIGITAL CONSTANT ARITHMETIC UNIT USING CONSTANT MULTIPLIER AND DIGITAL FILTER DEVICE

摘要

PROBLEM TO BE SOLVED: To contrive miniaturization, reduction of power consumption and speed up of an arithmetic operation by reducing the number and scale of adders in the constant multiplier. SOLUTION: In the constant multiplier 1 to perform multiplication between a definite multiplier 'M' and an indefinite multiplier 'X', when plural multiplication term groups 'β3j' (j is a positive integer) consisting of three power terms of 2 exist in a formula of power of 2 developed from definite multiplier 'M', a multiplication formula 'α1' is calculated from a multiplication formula 'α0' so that the group of multiplication terms are replaced with the multiplication formula 'α1' formed by multiplying the indefinite multiplier 'X' by a formula replaced with a multiplication term group 'γ3j' as a common term and a multiplication term group 'δ3j' left by binding the multiplication term group 'γ3j' and the constant multiplier 1 is constituted so as to perform multiplication of the multiplication formula 'α1'. The constant multiplier 1 is constituted by arranging an addition sign by making it correspond to the adder and arranging a multiplication sign by making it correspond to a shift circuit and a code converting part 105 to match the sign of the definite multiplier 'M' is provided at the last stage.