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This article mainly introduces the example analysis of Innovus input in PR, which has a certain reference value, and interested friends can refer to it. I hope you can learn a lot after reading this article.

Starting from innovus's user guide, I will find a medium-sized design exercise and send my study notes to the donkey account. This part of the content is too rudimentary and suitable for children and donkeys who don't understand from scratch.

The above figure is the flow chart in Innovus foundation flow user guide, which covers the entire PR process. Today, starting from the input requirements of PR, the input data requirements of PR are more or less the same as those of synthesis. The key parts are:

Timing libraries: Innovus supports three library formats: NLDM, ECSM and CCS. It is best to use ECSM or CCS after 65nm. The model is more accurate and less pessimistic than NLDM, and pessimism can be reduced by 5% to 10%. Usually, PR needs to be optimized by Multi mode Multi corner at the same time to ensure the consistency of libraries among different view.

Physical libraries: Innovus supports two physical information description formats, LEF and OA. So far, the old donkey has only used LEF but has not been exposed to OA. PR tools have more stringent requirements on physical libraries than integrated tools. In Genus, if a logic library unit does not have a corresponding physical library unit, the tool will automatically set the corresponding logic library unit to dont use, and an error will be reported if a physical library unit tool is missing in Innovus. At the same time, to define Non-Default Rules for Routing, NDR can be defined in LEF or in the process using the command add_ndr of Innovus. Like synthesis, when reading LEF, you need to read technology lef before other LEF. Make sure with library vendor or foundry that the LEF you get is up-to-date. In Tech-lef, you need to have the definition of all the VIA used by routing. If not, you can use the command setGenerateViaMode of innovus to generate it.

Netlist: Innovus requires that the input netlist is uniquified. If netlist does not do uniquify, you can set the variable "init_design_uniquify" to 1 before reading netlist, and the tool will automatically do uniquify when parsing netlist. Special treatment is required for master/clone partitioning. Some customers require that the netlist entered based on their special needs cannot have assign statements. You can use the command in Genus: remove_assign_without_optimization plus the corresponding option to delete the assign. If the assign in the netlist has not been deleted, you can delete it in the innovus with the command remove_assigns. By default, this command will replace the assign with a net, but some assign are directly connected to two port. If you do not add buffer, you cannot delete it. In this case, it is recommended to replace it with buffer with "remove_assigns-buffering". In fact, a new assign will also be introduced in the process of Innouvs optimization. If innovus is not added to the new assign, a variable can be added: set init_remove_assigns 1.

Constraints: including the constraints of SDC and users on the design. If you use the SDC written by synthesis and have made an appointment during synthesis, you need to modify the estimated value before reading SDC, and you also need to modify the ideal network and dont touch network in SDC. For example, some DFT or reset signals may not be modified during synthesis, but when you need to buffering these signals in PR, you need to remove the corresponding ideal or dont touch attributes. If you add additional constraints after init_design, you need to execute set_interactive_constraint_modes [all_constraint_modes-active] and then add the corresponding command. In addition to the SDC command, there are some constraints such as dont use and dont touch. These commands are not SDC commands but are commands set for object in design, and you don't need to set interactive_constraint_modes when adding.

Extraction: QRC file is used for RC extraction. The process before 65nm can be done with Captable file, but after 65nm, the accuracy of Captable is not enough, so it is highly recommended to use QRC file. In different stages of Innovus, different RC extraction engines will be used to extract RC such as TQuantus, IQuantus and so on.

Signal Intergrity Libs: in the process of innovus optimization, delay and glitch caused by SI need to be analyzed and optimized, which requires reading Noise Models, such as ECSMN and CCSN library, or reading cdB library.

ViewDefinition: define multi-Mode Multi-corner. You need to define library_set, operation condition, timing condition, rc_corner, delay_corner, constraint_mode, analysis_view, as shown in the following figure:

Innovus inputs the required files, and the settings on the input side can be summarized as follows:

Thank you for reading this article carefully. I hope the article "sample Analysis of Innovus input in PR" shared by the editor will be helpful to you. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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