It is always a pleasure to chat with Dr. Wally (Walden C.) Rhines, chairman and CEO, of Mentor Graphics. I chatted with him, trying to understand gigascale design, verification trends, strategy for power-aware verification, SERDES design challenges, migrating to 3D FinFET transistors, and Moore's Law getting to be "Moore Stress"!
Chip design in gigascale, hertz, complex
First, I asked him to elaborate on how implementation of chip design will evolve, with respect to gigascale design, gigahertz and gigacomplex geometries.
He said: "Thanks to close co-operation among members of the foundry ecosystem, as well as cooperation between IDMs and their suppliers, serious development of design methods and software tools is running two to three generations ahead of volume manufacturing capability. For most applications, “Gigascale” power dissipation is a bigger challenge than managing the complexity but “system-level” power optimization tools will continue to allow rapid progress. Thermal analysis is becoming part of the designer’s toolkit."
Functional verification is continually challenged by complexity but there have been, and continue to be, many orders of magnitude improvement in performance just from adoption of emulation, intelligent test benches and formal methods so this will not be a major limitation.
The complexity of new physical design problems will, however, be very challenging. Design problems ranging from basic ESD analysis, made more complex due to multiple power domains, to EMI, electromigration and intra-die variability are now being addressed with new design approaches. Fortunately, programmable electrical rule checking is being widely adopted and will help to minimize the impact of these physical effects.
Is verification keeping up?
How is the innovation in verification keeping up with trends?
Dr. Rhines added that over the past decade, microprocessor clock speeds have leveled out at 3 to 4 GHz and server performance improvement has come mostly from multi-core architectures. Although some innovative approaches have allowed simulators to gain some advantage from multi-core architectures, the speed of simulators hasn’t kept up with the growing complexity of leading edge chips.
Emulators have more than made up the difference. Emulators offer more than four orders of magnitude faster performance than simulators and emulators do so at about 0.005X the cost per cycle of simulation. The cost of power per year is more than one third the cost of hardware in a large simulation farm today, while emulation offers a 12X savings in power per verification clock cycle. For those who design really complex chips, a combination of emulation and simulation, along with formal methods and intelligent test benches, has become standard.
At the block and subsystem level, high level synthesis is enabling the next move up in design and verification abstraction. Since verification complexity grows at about the square of component count, we have plenty of room to handle larger chips by taking advantage of the four orders of magnitude improvement through emulation plus another three or four orders of magnitude through formal verification techniques, two to three orders of magnitude from intelligent test benches and three orders of magnitude from higher levels of abstraction.
By applying multiple engines and multiple abstraction levels to the challenge of verifying chips, the pressure is on to integrate the flow. Easily transitioning and reusing verification efforts from every level—including tests and coverage models, from high level models to RTL and from simulation to emulation—is being enabled through more powerful and adaptable verification IP and high level, graph-based test specification capabilities. These are keys to driving verification reuse to match the level of design reuse.
Powerful verification management solutions enable the collection of coverage information from all engines and abstraction levels, tracking progress against functional specifications and verification plans. Combining verification cycle productivity growth from emulation, formal, simulation and intelligent testing with higher verification abstraction, re-use and process management provides a path forward to economically verifying even the largest, most complex chips on time and within budget.
Good power-aware verification strategy for SoCs
What should be a good power-aware verification strategy for SoCs
According to him, the most important guideline is to start power-aware design at the highest possible level of system description. The opportunity to reduce system power is typically an order of magnitude greater at the system level than at the RTL level. For most chips today, that means at least the transaction level when the design is still described in C++ or SystemC.
Significant experience and effort should then be invested at the RTL level using synthesis and UPF-enabled simulation. Verification solutions typically automate the generation of correctness checks for power-control sequences and power-state coverage metrics. As SoC power is typically managed by software, the value of a hardware/software co-verification and co-debug solution in simulation and emulation becomes apparent in power-management verification at this level.
As designers proceed to the gate and transistor level, accuracy of power estimation improves. That is why gate level analysis and verification of the fully implemented power management architecture is important. Finally, at the physical layout, designers traditionally were stuck with whatever power budget was passed down to them. Now,they increasingly have power goals that can be achieved using dozens of physical design techniques that are built into the place and route tools.
According to Malcolm Penn, CEO, Future Horizons, the outlook for the global semiconductor industry in 2013 is likely to be +7.9 percent. This means, the global semiconductor industry will likely grow to $315.4 billion in 2013.
