VLSI circuits for low-power high-speed asynchronous addition

This paper presents a new low-power high-speed fully static CMOS variable-time adder. The VLSI implementation proposed here is based on the statistical carry look-ahead addition technique. The new circuit takes advantage of an innovative way of using a composition of propagate signals and of appropriately designed overlapped execution modules to reduce average addition time, layout area, and power dissipation. A 56-bit adder designed as described here and realized using AMS 0.35-/spl mu/m CMOS standard cells at 3.3V supply voltage shows an average addition time of about 4.3 ns and a maximum power dissipation of only 50 mW at 200-MHz repetitive frequency using a silicon area of less than 0.23 mm/sup 2/.