Mark Baker, Atrenta
EETimes (6/8/2015 07:09 PM EDT)
Higher quality of RTL delivered to the physical design team will have an impact on tge physical design team's ability to achieve design closure.
The quality of RTL delivered to the physical design team will have a major impact on design convergence, or more explicitly, the ability of the physical design team to achieve design closure.
Quality, in this case, refers to metrics used to assess the physical complexity of logic structures in the design. Design closure for completeness refers to closing timing, routability and area through physical design.
Typically, the analysis of physical feasibility (Figure 1) starts in the latter stages of physical synthesis and often carries through several cycles of physical design (place & route). Design teams will acknowledge that these iterations can be reduced if logic changes are made along critical design paths, however, back-end engineers generally lack insight into the design functionality, making changes impractical at this stage of the flow. Therefore, the investigation to narrow down and resolve the design issues often remains with the physical design team through a series of iterations that rely on floorplan changes, physical constraints, or high effort design optimization techniques. It’s not until these methods are exhausted that the issue will be passed back to the front-end designers. Once the relevant changes are made the entire cycle starts again. It is now easy to see why design schedules are so unpredictable.
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