Optimizing the antenna area and separators in layer assignment of multilayer global routing

Wen Hao Liu, Yih-Lang Li

Research output: Contribution to journalArticlepeer-review


Traditional solutions to antenna effect, such as jumper insertion and diode insertion performed at post-route stage may produce extra vias and degrade circuit performance. Previous work suggests combining layer assignment, jumper insertion, and diode insertion together to achieve a better design quality with less additional cost. Based on our observations on global and local antenna violations, this paper proposes an antenna-safe single-net layer assignment (AS-SLA), which first enumerates all antenna-safe layer assignment solutions of a net, and then extracts the minimum-cost one for the net. AS-SLA can minimize via count and separators as well. In addition, an antenna avoidance layer assignment flow (AALA) adopting AS-SLA as its kernel not only avoids global antenna violations, but also eliminates local antenna violations. Experimental results reveal that, in 16 benchmarks, AALA can yield ten antenna-violation-free assignments, while the algorithms of other works yield no antenna-violation- free assignment. However, AALA performs about seven times slower than other antenna-aware layer assignment algorithm. Accordingly, two acceleration techniques are proposed to reduce the runtime of AALA by 57.6%.

Original languageEnglish
Article number6774526
Pages (from-to)613-626
Number of pages14
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number4
StatePublished - 1 Jan 2014


  • Antenna effect
  • design for manufacturability
  • global routing
  • layer assignment
  • separator


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