ABSTRACT
Fixed-point addition is undoubtedly the easiest arithmetic operation to implement in any number representation. In fixed-point operations, the radix point is in a fixed location in the operand. The radix point is to the immediate right of the low-order bit for integers, or to the immediate left of the high-order bit for fractions. A ripple-carry adder is not considered a high-speed adder, but requires less logic than a high-speed adder using the carry lookahead technique. An n-stage ripple adder requires n full adders. A full adder can be implemented using two half adders. A half adder is a combinational circuit that adds two operand bits and produces two outputs: sum and carry-out. Carry-save adders save the carry from propagating to the next higher-order stage in an n-bit adder. They can be used to add multiple bits of the same weight from multiple operands or to add multiple n-bit operands.
