Top 5 Latest Routing Interview Questions and Answers

Creating physical connections to all the logical connections present in the design with the help of metal layers is known as routing.

  • PG Route: Power/Ground physical routing is completed during floorplan. Secondary PG routing happens just after STD cell placement.
  • Clock Route: Clock physical routing is completed during CTS after clock buffer insertion.
  • Signal Route: All the signal routing are completed after all the cells are placed which is called as routing stage.
  • All the Physical cells and Standard cells should be placed properly inside the core area.
  • Clock cells should be placed and clock routing should be completed. Clock NDR should be applied for the required or all clock nets.
  • Acceptable congestion, Timing (Setup/Hold), Power and Logical DRCs.
  • We should fix all the assign statements where 1’b0 should be connected via TIE low and similarly 1’b1 should be connected to TIE high cell.
  • ATPG and scan coverage should be proper. The entire design should have testability.
  • PDN report (Low Power report) should be clean.
  • Logical Equivalence should be clean.
  • Max Tran, Max Cap, Max Load etc. violations should not be too high. Marginal can be handled during routing or ECO stage.
  • Route all the signal nets with minimal physical DRCs.
  • Optimize Data path logic for timing, DRCs and Power.
  • Quality of route in a way, post route CTO is optionally performed.
  • Global Routing
  • Track Assignment
  • Detail Routing

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