Physical Synthesis - Place & Route

Physical synthesis is the process of converting a gate-level netlist into a physical chip layout which satisfies certain constraints. The layouts of the gates and their timing behaviour must be already given in a library. Usually the layouts are stored in a LEF library or separate GDS/OASIS files. The behaviour (logical and timing) is often described in 'liberty' files.

The following sections will cover the most important place & route steps and relate them to the relevant parts of the LibrEDA framework.

General idea of LibrEDA

The LibrEDA framework does not implement any place & route algorithms. But it provides fundamental data structures and interfaces. Place & route algorithms are developed as separate projects. As long as they follow the core ideas of LibrEDA they can easily be integrated with each other.

Example place & route flow

  • libreda-examples implements an example place & route flow. The program assembles parts of the LibrEDA framework into a stand-alone tool.


  • Electronic Design Automation: Synthesis, Verification, and Test (ISBN 9780123743640)
    • Some chapters can be found online:
    • Electronic Design Automation, Synthesis of clock and power/ground networks, (DOI: 10.1016/b978-0-12-374364-0.50020-5)