A 2.6-ns 64-b Fast and Small CMOS Adder

Hiroyuki MORINAKA  Hiroshi MAKINO  Yasunobu NAKASE  Hiroaki SUZUKI  Koichiro MASHIKO  Tadashi SUMI  

IEICE TRANSACTIONS on Electronics   Vol.E79-C    No.4    pp.530-537
Publication Date: 1996/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Ultra-High-Speed LSIs)
addition,  carry look-ahead adder,  binary look-ahead adder,  carry select,  modified carry select,  CMOS,  VLSI,  

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We present a 64-b adder having a 2.6-ns delay time at 3.3 V power supply within 0.27 mm2 using 0.5-µm CMOS technology. We derived our adder design from architectural level considerations. The considerations include not only the gate intrinsic delay but also the wiring delay and the gate capacitance delay. As a result, a 64-b adder, (56-b Carry Look-ahead Adder(CLA) +8-b Carry Select Adder (CSA)), was designed. In this design, a new carry select scheme called Modified Carry Select (MCS) is also proposed.