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)


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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