AXIEM software gains speed through its use of a hybrid meshing technology that uses both triangular and rectangular elements to create a mesh around a circuit or structure. The fully automated process is designed to apply the mixture of meshing elements that provides the highest accuracy with the minimal number of unknowns, thus keeping the computer memory and processing requirements to a minimum for a given simulation. Even for structures with curved forms or extruded planar geometries, AXIEM's hybrid meshing technology creates a true 3D mesh and provides a final solution that includes all X, Y, and Z currents on all surfaces.

The adaptive hybrid meshing technology will mix triangular and rectangular elements if the combination results in a more efficient and accurate mesh and simulation. It seeks the best combination of elements for the least amount of processing time needed to reach the highestaccuracy results.

As an example of the hybrid meshing technology at work, a 1000-mil-diameter microstrip structure fabricated on 32- mil Duroid 5870 substrate material was meshed and simulated within EMSight and AXIEM, respectively. When this structure was meshed with rectangular elements alone, it required a total of 3299 unknowns (rectangular elements) for full meshing and more than 40 s per frequency to simulate within EMSight. Employing AXIEM's hybrid meshing approach on this same structure required a combination of only 630 rectangular and triangular elements to fully mesh it and consequently resulted in considerably faster simulation time of only a few seconds per frequency.

This efficient meshing approach supports the analysis of circuits and structures with relatively thick metal conductors, providing accurate current flow simulations and solutions for thick conductors, even when the thickness of the conductor is greater than the width of the line. This thick-metal capability is essential for analyzing designs fabricated with 90- and 65-nm RF complementary metal oxide semiconductor (CMOS) processes. In these processes, the line thickness is often equal or even greater than the width of the line. The thick metal support is also useful when characterizing such structures as silicon spiral conductors or complete GaAs MMIC devices.

As a performance comparison, AXIEM and the company's closed-boundary EM simulation tool, EMSight, were both used to simulate the performance of a quarter- wavelength, 50O stripline conductor. In reviewing the results of the percent error as a function of analysis time, the new AXIEM simulator offers accuracy that is remarkably close to EMSight (Fig. 3).

AXIEM software was created for tight integration in the AWR design environment consisting of the Microwave Office, Analog Office^®, Visual System Simulator (VSS^TM), and Signal Integrity^TM software tools. It is seamlessly tied to the circuit and system simulation, layout, and verification functions of these various programs through a proprietary AWR unified data model (UDM). The UDM provides features such as extraction directly from circuit simulation without the need to perform explicit layout and EM setup steps. In addition, when used in conjunction with AWR's Automated Circuit Extraction (ACE^TM) technology, AXIEM provides fast, automatic interconnect model extraction, allowing EM structures to be modified and redesigned quickly.

Automated extraction flow allows seamless inclusion of EM results in any of the circuit simulations that are supported by the AWR design environment. It enables an operator to select the interconnects that are to be EM simulated and associate them with an extraction block. Any selected interconnections are automatically sent to the AXIEM simulator. AXIEM results are automatically merged back into the circuit description for simulation with any supported circuit simulator.

The AXIEM product is presently undergoing beta testing with select existing customers. In addition, AWR will send a free copy of AXIEM to all customers for an extended evaluation period (about 90 days). The software is geared for computers based on dual-core or quadcore microprocessors with at least 4 GB of random-access memory (RAM). It supports the latest Microsoft^TM operating systems, including Windows 2000, Windows XP, and Vista.

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