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Premier Planar EM Tool Integrated into Budget-conscious RF EDA Environment

September 18, 2007
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As traditional RF and microwave component designs move higher in frequency, the accuracy of physical design verification is a key enabling factor. EM solvers play an important role in the accuracy that drives high performance, small size and faster time to market for today’s designs.


The Agilent Genesys environment now has this EM accuracy built into the platform, delivering a powerful combination of a compact, general-purpose EDA environment, with the performance needed to achieve first-pass success at traditional high frequency design. The innovation is that first-pass success in a proven RF design can be obtained for around $15K US, including the industry’s premier planar EM tool, as well as a full environment with linear, layout, Yield/Optimization, SMT libraries and more (see Figure 1).

While the majority of RF EDA environments have been racing to embrace IC and multi-technology corporate design, they have left behind individuals and self-directed workgroups who work in smaller budgets, and support themselves without the benefit of corporate staffing and infrastructure for sophisticated design flows. Genesys, formerly of Eagleware-Elanix, satisfies this need. It integrates linear, layout, harmonic balance, Spice, RF system and synthesis into a multi-lingual environment, but does so in an affordable platform.

Now with an accurate planar EM tool tightly integrated inside, the Genesys environment has been re-energized for microwave component and subsystem design up to 100 GHz, and can do so at a price that enables the whole RF community, not just major companies.

This article explores some of the possibilities enabled by having Momentum within the Genesys platform. The Genesys 2007.08 release delivers other capabilities that are also of interest to self-supporting designers:

• New histograms and additional statistical capability for design-for-yield techniques
• Enhanced vendor parts libraries, now exceeding 30,000 parts
• Quick-start licensing, allowing users to be enabled worldwide, in minutes
• User Interface available in six languages (English, Russian, Japanese, Korean, and both Traditional and Simplified Chinese). Genesys is fast becoming the personal choice of RF designers worldwide (see Figure 2)

Applications

Genesys has a long tradition in the Eagleware-Elanix company for linear circuit synthesis and design. Genesys then added nonlinear simulation, transient, RF system simulation and more. With highly accurate planar EM, Genesys is now an attractive platform for a wider variety of design endeavors, such as:

• High performance passive structures
• Active physical designs with SMT commercial parts
• RF system design, incorporating layout-oriented parasitics
• Planar antennas

Proven Method of Moments Engine

Genesys Momentum GX is based on the Agilent Momentum planar EM engine, proven over a decade of use by thousands of engineers using MDS, Series IV, ADS, RFDE and now GoldenGate platforms. While there are a variety of planar EM simulators on the market, each has its advantages and disadvantages. Whereas these standalone planar EM solutions optimize either performance, price, or integration, only Momentum GX simultaneously leads in all three categories, and it does this by targeting specific RF and microwave applications. Momentum GX packages the accuracy of the finest EM techniques and makes them financially and functionally accessible to a wide audience of designers in a personal design package.

Passive Structures

Like all major RF EDA platforms, Genesys includes physical transmission line models with discontinuities, end effects and dispersion. These circuit models may be adequate for many circuit and IC designs, but even EM-based discontinuity models do not couple to each other, nor do they allow for novel structures and high performance component design.

A literature search of high performance design techniques reveals structures for which there are no models, which leads to intensive use of EM field solvers. Momentum GX with its conformal mesh, variety of boundary conditions, and unlimited number of layers and vias allows for creative approaches to high performance, high quality passive structures (see Figure 3).

Examples of such passive structures are filters, diplexers, resonators, launches, transitions, interstage matching networks, baluns, couplers, splitters and many more.

Genesys provides inexpensive synthesis modules that automate the creation of such structures, and these become a great starting point for more unique designs, if desired. Using the schematic, layout and linear simulation needed for a physical design, passive structures can then be optimized, tuned and statistical techniques applied, even with high performance EM (see Figure 4).

The Momentum GX planar EM solver gives passive physical designers confidence that the result will be accurate, even though the Genesys platform may operate more intuitively than IC design platforms.

Active Circuit Designs

Designers of multi-stage amplifiers, RF transceivers, and other components and subsystems also benefit from the accuracy and convenience of the Momentum GX simulator. For many years, Genesys users have had access to a Method of Lines planar EM solver called “Empower”.

As a square-grid mesh EM solver, Empower is less suited for complex designs, that is, designs with curved structures, open boundaries, and designs needing a critical accuracy for DC bias and skin effect loss than EM solvers with more sophisticated meshing technology.

Despite these limitations, the Genesys Empower module allows a seamless co-simulation between the electrical design with many surface-mount parts and the EM simulation of the passive metal interconnects. It does not require the placement of dozens of internal ports in the layout and handles the connection of the underlying S-parameter data automatically. Momentum GX continues this attractive Use Model (see Figure 5).

Users of Empower and similar industry EM simulators will benefit in a number of ways from adopting Momentum GX. Momentum GX preserves Empower’s seamless co-simulation model and extends performance to new levels. Momentum GX is nearly an order of magnitude faster than Empower, and uses far less memory for realistically-sized RF designs, allowing for greater complexity. It provides a direct DC solution for highly accurate bias, and superior loss prediction for thick metal and vias, which are needed by active circuits such as power amps. The “Automatic Frequency Sweep” (AFS) function and the RF (quasi-static) mode allow for even faster simulations relative to Empower.

Finally, the ability to interact with external RF Board drafting systems allows drawings to be imported and schematic parts with electrical connectivity to be placed on top of the artwork to be co-simulated with EM parasitics. This verifies critical areas of the final board layout and maintains closure of the RF design process with a minimum of organizational investment. While some RF EDA systems highlight a real-time 1:1 mapping between schematic and IC layout elements in the RF environment, this is impractical for designers constrained by real-world mechanical design flows, as well as design teams without the admin, library and integration support staff needed to maintain high levels of automation. Having a premier planar EM simulator and several input/output graphics translators, Genesys supports a variety of planar “back-ends” tying its schematic environment with verification and manufacturing. This also includes a direct path to rapid-prototyping machines. The Genesys environment provides a solid foundation for self-supporting, independent RF designers to create working design flows within a minimum cost envelope. Momentum GX further minimizes prototyping within those design flows.

The net benefit of having accurate physical simulations for arbitrary planar structures is creative confidence. Designers using Genesys can enjoy many of the same benefits for medium-sized RF component design as users of larger IC design systems, but because of its moderate cost, Genesys pays for itself in a matter of months, not years, without compromising the performance of the RF designs.

Physical RF System Design

Genesys is somewhat unique in that it allows the filters and passive structures of an RF system block diagram to be synthesized in place at the RF system level. Those filters and interconnect parasitics can now be rolled up to the RF system level with EM accuracy. Momentum GX will co-simulate with the Genesys Spectrasys and the Genesys linear simulator, allowing RF system architects to see the effects of physical design on spurs, mismatch, imperfect filtering and more, right at the RF system level (see Figure 6).

Planar Antennas

Antenna designers also benefit from Momentum GX by creating matching networks and feed structures to their planar designs, as well as identifying higher order resonances and radiation efficiency. The next release of Genesys will include additional capability for planar antenna design.

Conclusion

Agilent Genesys has always had a reputation for fast, easy circuit synthesis and linear design. With this sixth Agilent release within 25 months, Agilent is investing in Genesys to be the design platform of choice for self-supporting designers and small workgroups doing traditional RF and microwave design. With local language support in six different languages, and a full physical environment complete with a premier planar EM simulator under $15K (US list), Genesys opens a set of new possibilities for the entire RF design community.

Agilent EEsof,
Santa Rosa, CA (800) 829-4444,
www.agilent.com.

RS No. 300

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