•  
• EDN Europe MAGAZINE
•  
• Free SUBSCRIPTION
• Subscription Renewal
• View Media Kit

• EDN
• EDN Australia
• EDN Asia
• EDN China
• EDN Japan

Software turbocharges IC-logic simulation

With ICs becoming ever more complex and larger in gate counts, an ongoing demand exists for faster and higher capacity verification tools. EDA start-up Liga Systems addresses that need with its new NitroSim hardware-accelerated simulation environment. The company claims that the tool improves simulation performance from 10 to 100 times over single-CPU simulation and can handle designs with as many as 300 million gates.

Most of Liga’s creators were previously with Aptix. That company, which Mentor Graphics (www.mentor.com) purchased last year, mainly focused on prototyping boxes. Liga’s NitroSim is instead selling “turbocharged software simulation”, according to Chief Executive Officer Henry Verheyen.

NitroSim comprises three pieces of software and a custom PC board that users plug into their PCs. The NitroSim PCI, essentially an acceleration card, includes a custom VLIW (very-long-instruction-word) processor and lots of onboard memory with slots for expansion. The software includes the NitroSIM CC RTL (registertransfer- level) and gate-level netlist compiler for running designs on the NitroSIM PCI card; the NitroSIM TB compiler upgrade for running behavioral RTL netlists on NitroSIM PCI; and the NitroSIM RT runtime technology, which allows the NitroSIM to communicate with other simulation and test environments. The RT software also configures the PCI card.

Unlike accelerators, the NitroSim doesn’t map the design into an FPGA or a custom processor. Instead, the software compiles the code into memory instructions for execution by the VLIW processor. This approach allows the device to quickly run the design, says Verheyen, and avoids the problem of cache misses that limit the capacity scalability of pure-software simulators. “Software simulators run so slowly mainly because the amount of data the instructions are processing is many times larger than the on-chip cache,” says Verheyen. “The simulator is constantly running into cache misses, which means that the processor must stop every time and then go to memory to access the new data and instructions.”

A Virtex-4 holds the VLIWprocessor grid, which memory surrounds. The system feeds instructions into the grid from all memories in parallel, providing much higher bandwidth than a normal CPU, according to Verheyen. Because the system doesn’t rely on a logicsynthesis tool to compile the design under test into an FPGA or a custom processor, users can program behavioral RTL code into a NitroSIM system. NitroSIM supports testbenches, four-state handling, behavioral checks, and assertions. A NitroSIM for a 300 million-gate configuration sells for $50,000. —by Michael Santarini , Liga Systems, www.ligasystems.com.