Every spring, people in the US microwave industry eagerly anticipate the major product announcements that will be unveiled at the IEEE Microwave Theory & Techniques Symposium (MTT-S) International Microwave Symposium (IMS). This year's show in Honolulu, Hawaii, did not disappoint them. As always, the exhibition floor teemed with the latest RF components, materials, and product innovations. In addition, test and measurement advances were highly visible. Yet the show floor also reflected a growing trend: the increasing importance of software tools in the microwave industry. It used to be that only the large design houses could afford to use such tools. Over the last decade or so, the increasing affordability of these software tools has combined with their ability to ease bottlenecks at a variety of design stages. As a result, software design tools are now utilized by the majority of RF engineers. The software market has bloomed with this success, offering designers a wide variety of software products and companies from which they can choose.

In the area of three-dimensional (3D) electromagnetic (EM) simulation for high-frequency and high-speed components, for example, Ansoft (Pittsburgh, PA) just debuted HFSS v11 (Fig. 1). This version promises to enable users to perform immense simulations of structures that were previously just too large to solve. Essentially, HFSS v11 combines new higher-order, hierarchical basis functions with an iterative solver. That solver provides accurate fields using smaller meshes, which results in more efficient solutions for large, multi-wavelength structures. In addition, a fault-tolerant, high-quality, finite-element meshing algorithm allows HFSS to simulate very complex models two-to-five-times faster than previous versions while using half of the memory. Among the software's other new features are the following: an enhanced port solver, Floquet ports, a genetic algorithm to expand optimization choices, auto-assign capability for terminals, and Automatic Distributed Solve of discrete and interpolating frequency sweeps. This version also provides Distributed Solve for parametric sweeps, sensitivity, and statistical analysis. For an EM-based design flow, Ansoft dynamically links HFSS to Ansoft's combined frequency- and time-domain circuit simulator, Nexxim, and the company's integrated schematic and design-management front end, Ansoft Designer.

Another popular EM simulator vows to solve the current distribution on 3D and multilayer structures of general shape. Dubbed IE3D, it is a full-wave, method-of-moments (MoM)-based simulator from Zeland Software (Fremont, CA). In mid-March, IE3D 12.12 was released. This version introduced and implemented Conjugate Match Factor (CMF). As long as the chip impedance and basic configuration are provided, CMF allows the designer to judge the quality of an RFID antenna. In addition, the FastEM Design Kit for real-time, full-wave EM design allows engineers to parameterize both planar and 3D structures. They can perform high-accuracy and efficiency IE3D simulations on the structure and extract the FastEM signature from the simulation results. That signature allows the user to perform real-time EM tuning, optimization, and synthesis.

This version of Zeland's IE3D also includes network-distributed EM simulation and optimizations on IE3D, ZDS, and ZDM 12.1. The new implementation of ZDS and ZDM promises to help distributed and multi-license IE3D users to improve simulation efficiency by a factor of 10. In addition, IE3D Version 12.12 significantly improves the speed of the IE3D engine—even without multi-CPU support. An equation-based, schematic-layout editor with Boolean operations permits the engineer to create complicated layouts with parameterized objects in a schematic way. Because all object dimensions are equation-based, users can create structures beyond the coverage of the limited object types available in the library. IE3D 12 simulations automatically yield frequency-dependent, lumped-element, equivalent-circuit models.

Like IE3D, Sonnet Suites from Sonnet Software (Syracuse, NY) can be used in the design of monolithic microwave integrated circuits (MMICs), radio-frequency integrated circuits (RF ICs), planar antennas, and more. Yet the Sonnet Suites develop precise RF models (S-, Y-, Z-parameters or extracted SPICE model) for planar circuits and antennas. The software requires a physical description of a circuit, which comprises the arbitrary layout and material properties for metal and dielectrics. It then employs a method-of-moments (MoM) EM analysis based on Maxwell's equations, which includes all parasitic, cross-coupling, enclosure, and package-resonance effects.

In Sonnet Suites Release 11, which became available in March, co-calibrated internal ports introduce perfectly calibrated connections on the interior of a circuit layout. As a result, models may be connected in the user’s preferred frequency- or time-domain simulator. To remove cross-coupling between ports in the group, the co-calibrated ports are combined in Calibration Groups and simultaneously de-embedded. In addition, Release 11 uses a component to include an electrical- or circuit-theory model into an EM simulation. This component can calibrate the connection with respect to the terminal width of the connecting device. As a result, the discontinuity between a surface-mount pad and the component's terminal width is accurately characterized in Sonnet. It also is included in the EM analysis.

The Sonnet EM Analysis Engine, dubbed em, has now been enhanced for 64-b Windows and Linux platforms. Problem size is therefore limited only by the amount of random-access memory (RAM) on a user's computer. In addition, Release 11 of Sonnet Suites offers a redesigned and re-written Agilent ADS interface, called ebridge. It also simplifies Sonnet's well-known cluster-computing capability, which allows the designer to use many computers to solve large EM analysis. The analysis frequencies are divided between CPUs, which translates into a very sizable time savings. This cluster computing capability can be implemented on an existing computer network without third-party software.

Four separate 3D EM simulation tools comprise the CST Studio Suite from Computer Simulation Technology (CST) GmbH (Darmstadt, Germany): CST Microwave Studio for high-frequency applications, CST EM Studio for low-frequency and statics, CST Particle Studio for charged-particle dynamics, and CST Design Studio for synthesis and circuit simulation. These programs can all be accessed through the CST Design Environment. The latest version, CST Studio Suite 2008, is expected to become available in the fourth quarter of this year. Among this version's enhancements are two new interfaces that streamline the design workflow—especially for engineers involved in signal integrity. The native interface to Mentor Graphics—Expedition uses COM/COM to exchange data of entire layouts, areas, or nets. The second one, which is an ODB++ interface, enables access to layouts from a variety of tools like Mentor Graphics—Board Station and Zuken CR5000. In addition, users of CST Microwave Studio will be able to utilize Sigrity current distributions as field sources and export HSPICE models.

In terms of performance, this new version vows to improve the parallelization of transient and frequency-domain solvers. Plus, ongoing code-optimization projects with Intel guarantee that the latest and upcoming processor generations are fully leveraged. Dedicated hardware-acceleration boards are available for the transient solver. For the direct frequency-domain solver on tetrahedral grids, both memory-usage and speed improvements have been made. CST Design Studio 2008 also allows layouts to be created from schematic blocks for use directly in CWT MWS (Fig. 2). For the benefit of signal-integrity designers, IBIS and Berkeley Spice models can be included in CST DS simulations. Plus, a particle-in-cell (PIC) solver in CST Particle Studio 2008 can deliver the fully consistent simulation of charged particle dynamics in the presence of external and space-charge fields.