| 摘要 |
<p>A Wallace-type binary tree multiplier (Fig. 3) in which the partial products (Fig. 2) of a multiplicand and a multiplier are produced and then successively reduced using a plurality of adder levels (L1, L2, L3, L4, Fig. 3) comprised of full and half adders (FA, HA, Fig. 3). This reduction continues until a final set of inputs (Level L4, Fig. 3) is produced wherein no more than two inputs remain to be added in any column. This final set is then added using a serial adder (20) and a carry lookahead adder (21) to produce the desired product (po-p15). The additions at leach level are performed in accordance with prescribed rules to provide for fastest overall operating speed and minimum required chip area. In addition, the lengths of the serial adder (20) and carry lookahead adder (21) are chosen to further enhance speed while reducing required chip area. A still further enhancement in multiplier operating speed is achieved by providing connections to adders (Fig. 3) so as to take advantage of the different times of arrival of the inputs to each level (levels L1, L2, L3, L4 in Fig. 3) along with different adder input-to-output delays.</p> |
