Delay Optimization of Carry-Skip Adders and Block Carry-Lookahead Adders Using Multidimensional Dynamic Programming

  • Authors:
  • Pak K. Chan;Martine D. F. Schlag;Clark D. Thomborson;Vojin G. Oklobdzija

  • Affiliations:
  • Univ. of California, Santa Cruz;Univ. of California, Santa Cruz;Univ. of Minnesota, Duluth;Univ. of California, Davis

  • Venue:
  • IEEE Transactions on Computers - Special issue on computer arithmetic
  • Year:
  • 1992

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Abstract

The worst-case carry propagation delays in carry-skip adders and block carry-lookahead adders depend on how the full adders are grouped structurally together into blocks as well as the number of levels. The authors report on a multidimensional dynamic programming paradigm for configuring these two adders to attain minimum latency. Previous methods are applicable only to very limited delay models that do not guarantee a minimum latency configuration. Under the delay model, critical path delay is calculated not only taking into account the intrinsic gate delays, but also the fanin and fanout contributions.