Typical STD Cell Library Errors Fractal Technologies Typical STD Cell Library Errors 1/11/2019 Fractal Technologies Confidential

Typical Cell Presence Errors Obsolete Cells Cadence DFII has many times hierarchical cells that are not used anymore. (Artefacts) Double cell entries Cells removed from Cadence DB still remain in other formats. (Verilog, MilkyWay, Liberty, etc...) Missing Cells Wrong database in cds.lib included. Hierarchical cells are missing. Cells in the CDB do not exist in the other formats due to later added cells not all Databases are updated or an older database is delivered Documentation many times misses a cell Due to no formal checking method Filler and alignment cells not consistent for the various DB’s 1/11/2019 Quality in Design Formats

Typical Terminals & Pins Errors Direction of the pins does not match Input,Output, Bidirectional Pins are in the wrong layer Uses busses instead of single pins 1/11/2019 Quality in Design Formats

Quality in Design Formats Typical Label Errors Missing labels Simply missing Typing errors Uppor vs lower case errors Labels in the wrong layer 1/11/2019 Quality in Design Formats

Quality in Design Formats Typical Net Errors Missing net information Due to copy actions in the Cadence Database Net information may be lost. Database corrupt… Busses used instead of single pins 1/11/2019 Quality in Design Formats

Typical Layout vs. layout Errors Modifications in the master Cadence Database not copied to GDSII or LEF 45 degrees not accurately enough in LEF Abstract not generated correctly Shifted polygons  1/11/2019 Quality in Design Formats

Typical Abutment Errors 1 grid shift  Missing boundary layer Layers do not touch the outline 1/11/2019 Quality in Design Formats

Typical Routability Errors Pins not on grid Wrongly coded off-set 1/11/2019 Quality in Design Formats

Typical Functional Equivalence Errors Both active PRESET and SET yield different result over the various formats Priority definitions wrong Mismatch between asynchronous and synchronous descriptions Missing functional description Short circuit detection Cont… 1/11/2019 Quality in Design Formats

Typical Functional Equivalence Errors Documentation errors Due to missing formal checking. (Depends on human reading) pin(OA1) { direction : output ; function : "(!M2|(M1&M0))" ; pin(OA2) { direction : output ; function : "(M2|(!M1&!M0))" ; pin(Z) { direction : output ; function : "!(M1^M0)" ; .lib  Datasheet  1/11/2019 Quality in Design Formats

Typical Characterization Errors Last characterization entries all 0. Delay decreases with increasing output load Conditional vs non-conditional descriptions Back-annotation errors Conditions don’t match string based Obsolete default conditions Non-paired setup and hold times Swapping of Liberty file names ff, tt, vs ss 1/11/2019 Quality in Design Formats

Typical CCS Characterization Errors Cells do not have a single peak current Current curves have a “correction current” at the tail 1/11/2019 Quality in Design Formats

Typical ECSM Characterization Errors ECSM-curves have large deviations (20-300%) between ECSM and NLDM delay values 1/11/2019 Quality in Design Formats

Quality in Design Formats Conclusions It’s better to check the STD Cell Library before using it 1/11/2019 Quality in Design Formats