Delay abstraction in combinational logic circuits

Noriya Kobayashi, Sharad Malik

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


In this paper we propose a data structure for abstracting the delay information of a combinatorial circuit. The particular abstraction that we are interested in is one that preserves the delays between all pairs of inputs and outputs in the circuit. Such abstractions are useful when considering the delay of cascaded circuits in high-level synthesis and other such applications in synthesis. The proposed graphical data structure is called the concise delay network, and is of size proportional to (m + n) in best case, where m and n refer to the number of inputs and outputs of the circuit. In comparison, a delay matrix that stores the maximum delay between each input-output pair has size proportional to m x n. For circuits with hundreds of inputs and outputs, this storage and the associated computations become quite expensive, especially when they need to be done repeatedly during synthesis. We present heuristic algorithms for deriving these concise delay networks. Experimental results shows that, in practice, we can obtain concise delay network with the number of edges being a small multiple of (m+ra).

Original languageEnglish (US)
Pages (from-to)1205-1212
Number of pages8
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number10
StatePublished - 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Software
  • Computer Graphics and Computer-Aided Design
  • Electrical and Electronic Engineering


  • Combinational logic circuits
  • data structures
  • delay estimation
  • directed graphs


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