SoC design

Spend any time with Ansys’ John Lee, Rich Goldman or Marc Swinnen and you’ll hear plenty of optimism about the semiconductor industry even though they tick off a long list of looming design challenges. The need for reliable and effective electronic systems, they emphasize, is great and runs through high tech, aerospace and defense, automotive, IoT and 5G with communications being a common denominator. The three are especially bullish these days on changing market dynamics brought on by systems companies building company-specific bespoke, or custom, silicon. These systems companies are building chips with a different perspective and a fresh look at silicon design, a move away from the more traditional segment-specific silicon due to much more complexity. Ansys, a member of the ESD Alliance, a SEMI Technology Community, is a 4,100-employee company with a comprehensive portfolio of multiphysics engineering simulation software for product design, testing and operation products and services. John, Rich, Marc and I focused on Ansys’ semiconductor and electronics segment for our conversation. Smith: When did you notice the move by systems companies to build their own chips? What drives this trend? Lee: The inflection point was about three years ago when hyperscale data center and system companies recognized they needed an enterprise system design platform. They are designing bespoke silicon, driven to do this for cost efficiencies and to avoid relying on outside suppliers. They also want differentiation based on their specific platform needs so they can optimize compute power to their specific needs. Smith: What is driving the trend for multiphysics experience to ensure effective and reliable electronic systems? Lee: The increasing need for multiphysics analysis is acute. The physics of 3D IC, for example, brings in mechanical engineering with the convergence of mechanical and electrical as 3D emerges at the intersection of IC and System. As a result, physics becomes a necessity to analyze the stability of the chip in the package. Goldman: As well, the move to stacked chips, 3D IC and wafer-on-wafer requires thermal, electromagnetic and mechanical analysis in addition to the traditional analysis for function, performance and power. They all need to be analyzed together, not serially. It becomes multiphysics, not multiple physics. Smith: Two distinctly different disciplines – multiple physics and multiphysics – are needed for semiconductor design. How are they different? Why the need now? Swinnen: Multiple physics refers to the sheer breadth of physics that is now needed to analyze from the IC up to the largest system whereas multiphysics refers to the capability to analyze several physical effects concurrently, accounting for their impact on the design and interactions between various physics. Multiphysics are necessary to analyze the full context of the system environment – from nanometers to kilometers – for multi-chip packaging, chip-to-package-to-silicon and systems with multi-domain guidance. Goldman: A self-driving car, as an illustration, includes AI systems-on-chip, solid-state sensors, infotainment systems and radar/lidar detectors that must all work in the rain, the heat and the bitter cold. Smith: Why are design groups being reorganized to include expertise in mechanical and electromagnetic issues? Swinnen: Complexity has exploded, driven by a long list of technical requirements and, perhaps, mischaracterization. Goldman: Just consider the system on chip, mischaracterized by the semiconductor industry. The chip is never a system by itself. Rather, it is a complex component in a larger system and must be analyzed in that context. 3D IC is where this comes together and forces a recognition of physics outside the traditional scope of SoC design. 3D IC chips are much closer together on the board and it takes multiphysics embedded into the workflow of semiconductor design, packaging, system design and 3D IC to ensure they work reliably and efficiently. Smith: What is the solution? Goldman: It’s clear a specialized digital thread is necessary to move disparate groups with expertise in systems, physics and silicon together. Today, these groups or disciplines might not exist in the same company, whether it be a foundry, fabless or outsourced semiconductor assembly and test (OSAT) company. Lee: In order to unify the entire system design environment, a cloud-based, open and extensible heterogenous enterprise compute platform is required. It is similar to the SaaS-based business model and known as Simulation-as-a-Service (also SaaS). While vertical integration of design groups is already taking place at leading system design houses, there have also been advances in electronic design tools. These are starting to offer more comprehensive multiphysics capabilities including thermal, fluid dynamics (CFD), mechanical stress and reliability analysis in a single analysis cockpit. Today’s system designers face two platform challenges: First, they need an environment that is open enough to accept analysis results from multiple sources so that they can be overlapped and cross-analyzed. Second, the design platform must have the capacity to handle the enormous amounts of data generated by the latest 3-nanometer chips and 3D IC systems, and this implies an intimate coupling to elastic cloud computing. The days of an engineer writing Perl scripts and handing it off to someone else are gone. We believe that the industry is responding to this challenge with a new generation of design platforms that a cloud-native, open and extensible to allow heterogenous enterprise design. We are definitely at an inflection point in electronic design today, but the electronic industry has faced these before an we are confident it will master these challenges as well. About Rich Goldman Rich Goldman is director of marketing for the Electronics and Semiconductor Business Unit of Ansys. He holds a Bachelor of Science degree from Syracuse University and an MBA and Master of Science degree in Engineering Management. Moscow Institute of Electronic Technology (MIET)’s first honorary professor, he is also the recipient of honorary PhD degrees from Russian-Armenian (Slavnoic) University and State Engineering University of Armenia for contributions to the advancement of Armenia’s high-tech education and economic ecosystem. Rich served on EDAC’s board of directors. About John Lee John Lee is general manager and vice president of the Ansys Electronics and Semiconductor Business Unit. Lee co-founded and served as CEO of Gear Design Solutions (now Ansys), developer of the first purpose-built big data platform for integrated circuit design. He cofounded two other startups (Mojave Design and Performance Signal Integrity), which successfully exited into companies now part of Synopsys. He holds undergraduate and graduate degrees from Carnegie Mellon University. About Marc Swinnen Marc Swinnen is director of product marketing for the Electronics and Semiconductor Division of Ansys. He holds Master degrees in Electronic Engineering and Industrial Management from KU Leuven, Belgium, as well as an MBA from San Jose State University. About Bob Smith Robert (Bob) Smith is executive director of the ESD Alliance, a SEMI Technology Community. He is responsible for the management and operations of the ESD Alliance, an international association of companies providing goods and services throughout the semiconductor design ecosystem.

Adnan Hamid, CEO, founder and visionary of Breker Verification Systems, an ESD Alliance member based in San Jose, Calif., once described his job in chip design verification at AMD as “breaking things.” When it came to naming his startup, Breaker was a natural choice. After some consideration, the “a” was dropped and the company became Breker. Now Hamid is breaking the most complex semiconductor designs and Breker, moving from a startup to a scale-up company, is a noted part of the functional verification space. Smith: Why does verification continue to take the most amount of time in a project cycle? Hamid: The project cycle for semiconductor design has changed. Design abstraction has been raised to a much higher level than the days when developers were connecting logic gates. Today’s developers are typing functions that don’t include lower-level implementation details. Designs incorporate more blocks of reusable IP. Both reduce design time. Meanwhile, designs are getting bigger with more blocks of IP stitched together, all in need of testing. As design complexity grows, the amount of testing and verification increases as a square of design effort. One block requires one functional verification effort. Four blocks of IP mean up to 16 functional interactions require verification. While design is moving up the abstraction level, that’s not the case for verification, where plenty of detail must be reimplemented. Verification has certainly evolved, but engineers still think at the level of independent stimulus, response and coverage, driving the need to allocate so much time for verification. Smith: Are chips targeting artificial intelligence and machine learning applications more difficult to verify? If so, why? Hamid: Yes, absolutely and it’s an interesting challenge, especially given that machine learning is based on massively connected processing element arrays. Attempting to verify the individual processing elements and the critical interconnects is complex. AI device arrays and, interestingly, verification test content operation may both be thought of as a mathematical graph of processing elements and interconnect. Their operation involves walking through the graph form to generate a result. Finding the optimum path through these arrays is key. To understand how these systems may be effectively verified, it is worth investigating planning algorithms. Originally proposed by IBM, these hold the key to this type of verification process. The AI- style algorithm starts backward at the end of the processing element array and tracks down the most optimal and likely paths through it. At Breker, we have used these planning algorithms extensively to drive our graph-based test content synthesis process. Smith: Does system integration require verification? Hamid: Yes, it does. In the past, most functional verification has been performed at the block level. However, with the increase in more specialized SoCs, functionality is spread across multiple blocks, as well as the software running on the processors, driving full system-on-chip (SoC) functional verification. In addition, new requirements such as security and safety must be validated. A system-level infrastructure such as cache coherency and power domain execution has become more complex and these must also be tested. The new frontier in verification is ensuring a fully operational SoC. Of course, given the size of these SoCs, hardware-assisted verification such as emulation is essential, and porting tests from block simulations to SoC emulations has become a requirement. This porting process is problematic and this in turn has driven portable tests, giving rise to the idea behind Accellera’s Portable Stimulus Standard (PSS), of which Breker was a major participant. Indeed, some companies are taking this to the next level by composing their system-level testbench at the same time as they commence SoC architectural design, and then developing the hardware design, software design and test content all in parallel, in the so-called “shift-left” manner. Smith: Is “shift-left” a growing trend that are you seeing in verification? Hamid: Yes. Shift-left is taking hold in hardware and software design, giving way to an increase in early test content composition. Then as individual blocks are finished and connected, their verification is driven from this same test content, saving a significant amount of time and effort. This is a huge verification and test generation change that was inevitable given the increased time-to-market constraints and SoC complexity. Figure 1: Shift-left is ushering in the next generation of SoC verification. Source: Breker Smith: As an entrepreneur, what advice would you give someone founding a startup or thinking about starting one? Hamid: Do not take the attitude “Build it and they will come.” My best advice for an entrepreneur or fledgling entrepreneur is to solve a specific customer problem, however narrow it might seem. Including services as part of a product offering and developing partnerships with other vendors helps with this and turns your company into a solution provider not a product developer. This is essential for getting the right products to market on time and within budget, and then ultimately scaling them across the market. The ESD Alliance and Accellera are hosting a two-part webcast series on the work-from-home experience titled Remote Work, Remote Chip Design: Building Chips During a Pandemic. The first panel, Wednesday, June 9, at 9:00am PDT, will feature a discussion led by Tom Fitzpatrick, strategic verification architect from Siemens EDA verification engineers through their experiences converting their home offices into verification test labs. The second panel in July will explore how executives managed a remote workforce and explain how they plan to bring employees back to physical offices. About Bob Smith Robert (Bob) Smith is executive director of the ESD Alliance, a SEMI Technology Community. He is responsible for the management and operations of the ESD Alliance, an international association of companies providing goods and services throughout the semiconductor design ecosystem.