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Apache tool additions jazz up NSpice simulation

Posted: 03 Feb 2004 ?? ?Print Version ?Bookmark and Share

Keywords:apache design solutions? nspice simulator? nspice-pi? nspice-usb? blsn solver?

Physical-design-integrity startup Apache Design Solutions Inc. has introduced two new versions of its NSpice simulator: NSpice-PI, for power integrity, and NSpice-UBS, for ultrawide-broadband simulation of low-frequency effects on high-speed circuits.

Power and ground mesh extraction and simulation are becoming a necessity as process geometries shrink and chip performance rises, said Andrew Yang, president and CEO of Apache. Improper simulation of such effects is becoming a more common cause for chip failures, he said.

Traditional Spice simulators lack either the ability to simulate power and ground mesh accurately or the memory to do so, Yang said. He included Apache's standard version of NSpice in that characterization.

"Fast Spice simulators that use lumped RLC [resistance, inductance, capacitance] can handle the memory requirements, but they can't accurately simulate a mesh network," he said. "In a mesh network, every node affects every other node, and accurate modeling of inductance can't be done with RLC fast Spice engines."

To address power and ground mesh, Apache has added what it calls the BLSN (big linear, small nonlinear) Solver on top of the C++ modern data structure of the NSpice engine to create NSpice-PI.

The company claims the BLSN Solver can simulate mesh networks, Vdd and N-port, S-parameter elements. When running on a workstation with 16GB of RAM, the tool can handle netlists containing more than 5 million nodes, with over 25 million RLC elements, multiple S-parameter elements and more than 100,000 transistors, the company said. Each of the S-parameter elements can have several hundred ports and each of the ports its own reference, Apache said.

The other new tool, NSpice-UBS, is designed for simulating very high-speed circuits over relatively long time spans to capture lower-frequency effects such as ripple or modulation. Such effects are common in high-speed serializer-deserializer circuits and phase-locked loops, the company said.

Keith Mueller, VP of worldwide sales and marketing at Apache, cited the analysis of a high-performance multigigabit/second transceiver as an example. Designers need to analyze the impact of power ground noise as well as crossover modulation on the multigigahertz data transmitted in the channel, he said. Because of the intrinsically large size of the power-ground structure, the spectrum of power-ground noise is in the lower tens of megahertz, while the data signal may be in the tens of gigahertz, Mueller said. The analysis must therefore cover a broad spectrum, he said.

NSpice-UBS addresses that requirement by reading accurate S-parameter data directly and then calculating in picoseconds the precise time step needed to replicate the accurate high-frequency signal, Mueller said. The simulator runs fast enough to cover the microsecond-long simulation duration required to analyze the modulation.

Both NSpice-PI and NSpice-UBS are available immediately on 32-bit Linux and 32-bit or 64-bit Solaris platforms. A 64-bit Linux version will be available soon, according to Apache.

The list price for a one-year time-based floating license for NSpice-PI is $60,000 on any platform. A one-year floating license for NSpice-UBS is priced at $35,000.

Apache added the BLSN (biglinear, small nonlinear) Solver atop the C++ data structure of the NSpice engine to create NSpice-PI, for power integrity.

- Mike Santarini

EE Times

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