Apsim and NEC announce new power and ground modeling software for LSI design noise analysis (ApSim)

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San Jose, California - January 29, 2001 - Applied Simulation Technology announced ApsimLPG, a new software tool aimed at predicting high frequency currents in LSI designs. The tool was co-developed with NEC Corporation (Tokyo, Japan). The target application is to analyze internal current flow in large IC ’s for the purpose of predicting EMI. The software works in conjunction with an extracted net list, which can contain millions of transistors and the parasitic interconnect information. The net list is reduced and simplified to a very small number of SPICE transistors or IBIS description plus the interconnect system using proprietary techniques. The electrical characteristics of the resulting circuitry must closely match those of the original large net list in order to achieve reliable accurate results. ApsimLPG has shown good agreement with measurement waveforms within 3dBuA for a wide frequency range in a 32 bit micro controller LSI.

Accurate current and power prediction in LSI designs has become an issue partly due to the rapid growth in the portable, wireless, consumer and automobile industries. This fact coupled with continued sub-micron shrinkage, operating frequencies in the GHz range and a much higher level of integration has produced a real need for such tools. Using SPICE transistor level net lists for LSI noise analysis is not practical, thus simplification and use of higher-level tools has become more popular. ApsimLPG effectively reduces these large net lists into more manageable sizes and then performs time domain and frequency domain analysis to predict the currents. The resulting model consists of clock and non-clock nets. The major dynamic currents flow from clock nets, which consist of approximately 10% of the total circuit size. The model for the clock nets is described in a condensed fashion and includes pre-driver, drivers and flip-flop circuits. The remaining 90% of the design consisting of non-clock nets is modeled as static filters or de-coupling capacitors.

Three different model types are supported, traditional SPICE transistors, IMIC Table SPICE format, and IBIS. Users can choose the model level and type used. This can range from a few hundred transistors too as little as 16 or 4. In the IBIS case 8 or 2 inverting output stages can be used in the simplest case. There is a tradeoff between accuracy and simplification. Industry standard IBIS EBD (Electronic Board Description) format is also available. The IBIS model is described by a circuit consisting of two or eight output inverters with the associated interconnect system. The IC interconnect system consists of RC components in series and forks representing EBD so that existing IBIS Simulators or IBIS Translators can use this model with no change.

ApsimLPG is integrated with the company’s EMI/SI prediction software and device modeling tools such as ApsimIBIS_Toolkit, ApsimTranslator, ApsimIBIS_LCR and ApsimTSG. ApsimLPG can be used to predict an LSI’s emitted radiation due to it’s internal transistors and interconnects as well as its packaging interconnect system. Conventional software systems predict EMI from an IC’s I/O cells only, neglecting core logic. The currents from core logic are much larger and their operating frequency is much faster than the I/O. With today’s designs this leads to inaccuracies since the core logic and associated interconnects can play a significant part of the power consumption. ApsimLPG is designed to overcome this problem as well as giving designers better understanding of the power consumption issues.

ApsimLPG pricing in the USA starts at $20K for the basic package. ApsimLPG also needs other related tools such as ApsimIBIS_Toolkit, which extracts IBIS data from various SPICE programs.

Applied Simulation Technology provides modeling and simulation software for the CAE EDA market. The company is a leader in providing solutions for Signal Integrity and EMI issues.

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