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  • Foolproof Your IP before it Stumbles in Higher-up Design

    SoC designs are increasingly becoming assemblies of a large number of IP blocks. A well integrated assembly can lead to a successful PPA (Power, Performance and Area) optimized design. However, it is equally important that each IP block is optimized, robust, and integrable in the design. The complexity of an IP and its integration can be so high that any kind of re-work can prove to be very costly. This issue has been recognized by the SoC design industry; otherwise we wouldn’t have seen the emergence of IP cataloging for choosing the best IP for a particular function in an SoC. A semiconductor services company, eSilicon has gone much beyond cataloging by providing “Try IP Before You Buy” kind of services where you can check whether your chosen IP fits well in your SoC environment or not.

    Article: 20nm IC Design at IBM using Cadence Tools-repair_sch.jpgThe point is, in the current IP and SoC market one cannot afford to lose on design time and miss occasionally available, small time-to-market window. Before using an IP for integration, a quick check on its quality and suitability for integration can save a substantial amount of rework down the SoC integration and verification flow. This can also enable you to better predict your SoC design and verification schedule. This is explained very well in a graph provided by Fractal Technologies which depicts how repair time during SoC integration after IP shipment starts increasing exponentially, thus destabilizing overall design schedule.

    Fractal’s Crossfire has more than 200 checks to assess the quality and suitability of an IP for integration into an SoC. It has automated and integrated viewing, debugging, and reporting capability. Also, it provides user-induced waiving for particular rules to prevent unwanted checks, thus accelerating the consistency validation of an IP. The Crossfire also provides APIs for users to create their own custom checks for particular IPs.

    Checking IPs is not as simple as it appears to be. A typical problem faced by designers is to maintain consistency among various formats encompassing different IPs and their integration into an SoC. The complexity of SoCs, IPs in various forms from third party suppliers across the world, and different levels of design abstractions and validations have led to significant increase in the number of formats to be supported at each level in the design flow. It’s essential that the consistency between these formats is maintained to avoid unnecessary iterations in the design flows. Consider the diagram below which represents several aspects of an IP, each represented in multiple formats and databases.

    Article: 20nm IC Design at IBM using Cadence Tools-format_support.jpg

    The Crossfire supports each of these formats and checks for consistency between different aspects of an IP to ensure its integrity at all levels. The sheer number of views including functional representation, netlist, timing, power, reliability, layout, and test makes it really a difficult task to check the consistency at each level. It needs automated tool like Crossfire. The deep sub-micron processes have introduced another level of complexity to manage manufacturing variability at the design level, adding a few more formats to represent variability in the design flow.

    The Crossfire ensures that the information represented across these views is consistent and does not contain any anomaly. In case of any mismatches or even modeling errors, Crossfire promptly reports it. A timely correction of such errors saves a lot of debugging and rework later during SoC integration. The Crossfire has a very easy-to-use GUI with graphical debugging, filtering, viewing and several other features for quick investigation into a design. There is automatic setup for batch runs as well. The existing customer scripts can be easily integrated into Crossfire environment. Also, there are APIs for creating database independent checks.

    As it is evident, in today’s SoC and IP environment new formats keep evolving. The Crossfire has a robust methodology for adding new format support in its IP validation scheme. The detail about this methodology is given in a whitepaper at Fractal website. In the first half of this year, Fractal had added support for several new formats including APL, UPF, CTL, and AOCVM into Crossfire for IP validation. Most recently, it has added support for Spice v2lvs variant.

    Along with the new format addition, Crossfire keeps adding a number of new rule checks with respect to the new format as well as existing formats as the checks are discovered internally at Fractal or during various IP checks at customer sites.

    A tool like Crossfire can be relied upon for checking the quality and consistency of an IP before its integration into an SoC, thus shortening the overall SoC design schedule. Also, by using this tool the SoC integration schedule can be made more predictable.


    Pawan Kumar Fangaria
    Founder & President at www.fangarias.com