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Figure 6: Comparison of delay results from K-factor and nonlinear modelsNote the more accurate IR drop-on-delay results with the SignalStorm NDC nonlinear model in cell 1,compared to K-factor derating.3.5SignalStorm NDC in the design flowAny new delay calculator must be integrated easily into existing STA flows. SignalStorm NDC is compatiblewith industry-standard libraries and accepts both .lib files and the new nonlinear current source libraries.SignalStorm NDC can read parasitic information in standard DSPF or SPEF formats. SignalStorm NDC alsoaccepts instance-based IR drop data from the Cadence VoltageStorm®power analyzer to account for theimpact of IR drop on path delays (see Figure 7). Figure 7: SignalStorm NDC interaction with other toolsOutput is produced in familiar formats for popular static timing analysis tools—standard delay format(SDF) files, for example. Reports also are available. Other features include automatic library characterizationand job management. 4REAL-WORLD SUCCESSESSignalStorm NDC has been used with dozens of commercial designs. In the first case study described here,several designs were analyzed using SignalStorm NDC. The results demonstrate its capabilities in providingmaximum speed with decreased memory use, independent of hardware performance. In the second casestudy discussed, a design that passed traditional delay calculation but failed in silicon was analyzed againusing SignalStorm NDC, which accounted for IR drop. The new analysis pinpointed the cause of the failure. 6IR drop/EMVoltageStormEncounter platform or third-party SP&RDelay calculationSignalStorm NDCEncounter platform or third-party STACrosstalk analysis CeltIC.lib or ECSMRepairsSDFIR dropSPEFExtractionFire & Ice QXC or third-partyK-factor (derate) for cell1Accurate modeling by SignalStorm NDCDelayVoltage0.0E+000.70.80.91.01.11.21.32.0E-094.0E-096.0E-098.0E-091.0E-081.2E-08cell1cell2cell3cell4