News and New Products

AWR's new EM simulator touts flexibility

By Michael Santarini, Senior Editor -- EDN, 9/11/2007

You don’t usually associate the word “flexibility” with an EM (electromagnetic)-analysis tool but the folks at AWR (Applied Wave Research) want to change that conception with the introduction of the Axiem EM-analysis tool. Axiem targets designers doing 3-D planar applications, such as RF PCBs (printed-circuit boards) and modules, LTCC (low-temperature-cofired-ceramic) packages, MMICs (monolithic-microwave integrated circuits), and RF-IC designs. The tool will compete with EM solvers from Ansoft, Eesof from Agilent, and others.

According to Sherry Hess, product-marketing manager at AWR, EM-analysis tools, even AWR’s own legacy EM simulator, EMSpice, which the company continues to support, have traditionally fallen into one of two bins: either accurate but slow or inaccurate but speedy and with low dynamic range. Most designers encounter design projects that require the positive attributes of both types of EM analyzers. Because no EM tool until now was both blazingly fast and accurate, these designers often had to buy both types of tools. Axiem eliminates this need because it allows users to tune its runtimes and accuracy to their suit their needs. The speedup is so significant, Hess claims, that users will find it useful for both design and postdesign analysis.

 To suit the tool for growing design complexities, AWR outfitted it with a new hybrid-meshing solver technology and built the tool from the ground up to run on multicore processing platforms. “Axiem is ‘open-boundary,’” says Hess. “It has hybrid meshing, is extremely flexible, and will grow and expand as changes in IC and PCB modules take place. The more complicated designs get, the more designers will need the technology.”

Traditionally, fast EM-analysis tools employ solvers based on a Sommerfeld integral equation to speed analysis, but the speed increase often comes at the expense of accuracy and dynamic range, scaling up runtimes by a factor of three as design complexity increases. Axiem’s solver employs a fast multipole method that the company has tweaked for full-wave analysis. This approach essentially allows the tool to scale runtimes even faster as design complexity increases, maintaining accuracy, and running analysis faster than older tools.

To perform EM analysis, tools traditionally divide a structure into smaller areas with meshes of rectilinear shapes and then analyze those shapes and their relationship. But microwave and RF designs often include nonrectilinear structures, such as spiral inductors that are difficult to mesh and analyze. To combat this problem, EM-tool vendors have introduced tools that use a triangular mesh, which increases accuracy but lengthens runtimes. To get the best of both worlds, AWR gave Axiem a hybrid-mesh system that automatically assigns rectilinear mesh to regular structures or regular parts of an irregular design feature and triangular mesh to any unique features, thus optimizing the runtime and accuracy of a simulation run. The tool automatically tweaks which features receive a rectilinear mesh and which receive a triangular mesh. The tool’s meshing can also handle the increasing thickness and the width-to-height ratio of conductors in newer process geometries, accounting for silicon irregularities on the X, Y, and Z axes.

“With high-frequency effects, you typically have a lot of the information you have to capture before you can do additional circuit simulation and harmonic-balance simulation, and it has to be accurate down to dc,” says Hess. “Our simulator spans dc. You don’t have to do a dc simulation, then do high-frequency analysis, and then mathematically stitch these two together. The solver spans the full range.”

The tool takes advantage of computer systems employing multicore-processing technology, optimizing the system for quad-core processors. It also ties into AWR’s Ace technology, in which all AWR tools run from a single data model, allowing all the tools in the AWR lineup to share design data. The tool links through Ace into OpenAccess so that it can share data with other third-party tools using OpenAccess. The company has not released any metrics of runtime because the tool is still in beta production, but the company expects to have more data on the tool’s performance in the coming months. AWR plans to release the tool for mass distribution by the first quarter of next year. The price for a single-user, node-locked, perpetual license, running on Microsoft operating systems, starts at $30,000.