by Debra Vogler, Senior Technical Editor, Solid State Technology
Targeting 45nm design, Cadence announced several new design flows that will be part of the 7.1 release of its Encounter digital IC platform in October.
Described by the acronym WYDIWYG (“what you design is what you get”), the flows leverage products from the acquisition of Praesagus (CMP Predictor) and ClearShape Technologies (InShape and OutPerform, for physical and electrical variability analysis). A new NanoRoute fast litho approximation tool integrated into the routing stage is aimed at preventing the inclusion of risky/sensitive structures that could become problematic litho hot spots later if left “as is.”
Statistical timing analysis is enabled with a new Encounter Timing System GXL capability. This addition is significant, because “The more of the variation you can model deterministically the better, and any variation you can’t model deterministically, you have to clean up with statistical timing,” explained Eric Filseth, Cadence’s VP of Encounter marketing.
The company is pushing the ability of its new statistical timing analysis models to recapture design margins that are lost by multi-corner/worst-case timing analysis scenarios. Adding the capabilities to capture lithography and CMP effects can be significant (see figures above and below) — Cadence partners found cases where as much as a 22% difference in circuit timing and 300% in leakage power could occur if the models were not used.
Cadence’s “pyramid” strategy for tackling DFM at 45nm begins with the acknowledgment that the router has to do most of the critical baseline work — the more problems that can be caught early and removed from a design, the better. Next in line is performing systematic variation analysis, which is what the litho, CMP and other models do. These tools are followed by the finer-grained optimization that goes beyond grid and track-based layout. The top two layers of the pyramid are analyzing whatever random variation remains and analyzing temperature effects. It appears that Cadence will have more announcements going forward that address the top layers of their pyramid strategy. — D.V.