A 54×54-b regularly structured tree multiplier

A 54-b×54-b parallel multiplier was implemented in 0.88-μm CMOS using the new, regularly structured tree (RST) design approach. The circuit is basically a Wallace tree, but the tree and the set of partial-product-bit generators are combined into a recurring block which generates seven partial-product bits and compresses them to a pair of bits for the sum and carry signals. This block is used repeatedly to construct an RST block in which even wiring among blocks included in wire shifters is designed as recurring units. By using recurring wire shifters, the authors can expand the level of repeated blocks to cover the entire adder tree, which simplifies the complicated Wallace tree wiring scheme. In addition, to design time savings, layout density is increased by 70% to 6400 transistors/mm², and the multiplication time is decreased by 30% to 13 ns