Electronic Design

Electromagnetic Analysis Moves To The Front End

Generally, electromagnetic (EM) analysis has been something that’s waited until the back end of the design cycle as a verification step. With so many end products now requiring some amount of EM analysis, it’s too often applied too late to catch fixable problems. Applied Wave Research’s Axiem EM design software brings EM analysis to the front end, where it can serve as a true diagnostic design tool that helps shorten the cycle. The Axiem product was developed specifically for 3D planar applications, such as RF printed-circuit boards (PCBs) and modules, low temperature co-fired ceramic (LTCC), monolithic microwave integrated circuit (MMIC), and RFIC designs.

The Axiem technology is an open-boundary, non-gridded, method-of-moments (MoM) solver that supports true thick metal in layered dielectric media. The tool is said to exploit recent advancements in EM solver and meshing algorithms, as well as computer architectures, to up the ante in terms of speed and accuracy.

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Overcoming Limitations

The solver algorithm within the Axiem technology is intended to overcome the limitations of existing 3D planar formulations that rely on the Sommerfeld (or similar) integral. Such formulations deliver simulation speed, but at the cost of accuracy and dynamic range. Axiem’s solver algorithm uses a proprietary technique that’s best described as similar to the fast multipole method, yet adapted for full-wave analysis. As such, the Axiem solver algorithm scales on the order of N log(N) as opposed to N3 (the case for most existing MoM products).

The Axiem product’s solver technology also lets users accurately and robustly simulate to dc, which is essential for obtaining the right bias conditions and setting the dc operating points for active structures. The integrity of these broadband results mitigate any design hiccups that may be associated with using the “dc-to-daylight” results in a subsequent harmonic balance or transient simulation, such as those integrated within AWR’s design environment.

In addition, the Axiem product includes autocalibrated internal ports, which maintain their own current return path with relatively low error. These ports eliminate the need for manual de-embedding or an explicit path to a sidewall (i.e., edge ports), and are the ideal excitation for complex structures such as PCBs with many surface-mount pads.

A hybrid meshing technology within Axiem automatically fractures structures with triangular and rectangular elements, and is optimized to maximize accuracy with minimal unknowns. This heuristic approach extends the capacity reach of Axiem above and beyond traditional single-element approaches. Consequently, it becomes a highly suitable EM tool for signal-integrity analysis of large RF PCB designs.

The Axiem technology’s meshing algorithm also supports "thick metal," in that it creates 3D meshes of extruded planar geometries, accounting for all x-, y-, and z-directed currents on all surfaces. This thick-metal capability is a prerequisite for successful design of 90- and 65-nm RF CMOS devices, where line thickness is often in parity (1:1 ratio) with line widths. Similarly, thick-metal support is further required to correctly characterize silicon spiral inductors, as well as very large designs like complete GaAs MMICs.

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Fitting Into Flows

The Axiem product functions as a standalone EM solver, but it also integrates well with the overall AWR design flow. The tool is closely tied to circuit and system simulation, layout, and verification through AWR’s unified data model (UDM). The UDM provides features such as extraction directly from simulation without having to perform explicit layout and EM setup steps, thereby incorporating EM directly into circuit simulation.

Furthermore, when the Axiem design tool is used with AWR's ACE technology, which performs fast, automatic interconnect-model extraction, the same EM structures can be modified and designed in seconds accordingly with ACE. Subsequently, they can be more accurately modeled or analyzed within the mainstream design flow using the Axiem tool.

Axiem is now in beta test with select existing customers. The commercial release is scheduled for the first quarter of 2008. The product is priced in the U.S. at $30,000 for locked licenses and supports Windows 2000, XP, and Vista. For international pricing or general availability information, contact AWR directly.

Applied Wave Research Inc.

http://www.axiem3d.com

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