| 摘要 |
PURPOSE: To reduce a chip area and to speed up calculation speed by obtaining the difference of two constant values through the use of a subtracter and directly calculating an absolute value with the value of the difference. CONSTITUTION: The subtracter is composed of one exclusive OR gate (XOR), two inverters (IN) and NAND gates (NA). XOR 1 exclusively operates a minuend A and a subtrahend B and outputs a difference signal D0. IN1 inverts the output of the output D0 of XOR1 and outputs a difference signal D1. NA2 logic-combines the subtrahend B and the output of XOR1. IN2 inverts the output of NA2 and outputs a borrow value B0, NA1 logic-combines the minuend A and the output D0 of XOR1 and outputs a borrow value B1. Thus, absolute value calculation time reduces, the chip area can be reduced and the absolute value can be calculated at high speed. |
