The Design of an Asynchronous Carry-Lookahead Adder Based on Data Characteristics

  • Yijun Liu
  • Steve Furber
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3728)

Abstract

Addition is the most important operation in data processing and its speed has a significant impact on the overall performance of digital circuits. Therefore, many techniques have been proposed for fast adder design. An asynchronous ripple-carry adder is claimed to use a simple circuit implementation to gain a fast average performance as long as the worst cases input patterns rarely happen. However, based on the input vectors from a number of benchmarks, we observe that the worst cases are not exceptional but commonly exist. A simple carry-lookahead scheme is proposed in the paper to speed up the worst-case delay of a ripple-carry adder. The experiment result shows the proposed adder is about 25% faster than an asynchronous ripple-carry adder with only small area and power overheads.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Yijun Liu
    • 1
  • Steve Furber
    • 1
  1. 1.APT Group, School of Computer ScienceUniversity of ManchesterManchesterUK

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