Expert Advice: The Real Power of Microwave CAE Software
During a CAE seminar in the late 1990’s, I asked a large group of RF and microwave engineers about the software that they actually use for design.
Overwhelmingly, these engineers responded that they use schematic entry and linear simulation but little else. When asked specifically about nonlinear and electromagnetic simulation, only about ten percent were actually using these tools. The rest of the engineers described these simulators as expert tools that were difficult to use. Probing more deeply, I discovered that many of these same engineers were having problems with excessive design turns, even though simulation technology which would have prevented these turns was available to them.
What has changed over the past ten years in microwave CAE software? All of the vendors, Agilent included, regularly work on improving usability, each in its own way. Vendors and customers will argue over which is better, but all have made progress. Although these advances have given us usability improvements, we have not seen the kinds of revolutionary improvements enjoyed by other software industries. We have all witnessed attempts by smaller companies to bring usability to the forefront   . We have seen their products settle into mature software platforms, complete with their own legacy issues.
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During this same 10 years, Linux has gone from an obscure, text only operating system to a major platform, complete with a modern user interface. Windows has proceeded through Windows 98, NT, 2000, ME, XP, and Vista. Microsoft Office 97 (7.0/8.0) was brand new and was the first Office version to not require floppy disk installation. Virtually all web-enabled applications have been completely developed in this time. In contrast, RF and microwave software, by and large, looks like it did at the turn of the millennium.
The Case for Change
While user interfaces in microwave CAE software have remained relatively stable, important strides have been made in simulation technology. Today, more designs incorporate integrated chip, package, module and board systems which are more difficult to design, analyze, debug and deliver in high-volume than the typical design of 10 years ago. At the same time, due market & economic pressures, designers are expected to deliver product with first-pass success in less time.
In recent visits to companies facing these challenges, I regularly see the elaborate tool design flows and processes these companies have established to try to keep ahead of these pressures. Even though these customers have access to tools from all major vendors that contain all the simulation power they need to help them achieve first-pass success, they still resort to error-prone manual processes for much of their flow.
One challenge that many designers face is in the area of signal integrity. Engineers need to analyze complex signal paths including such features as chip landings, bond wires, solder balls and traces. Electromagnetic simulators have made dramatic increases in capacity and performance and are now capable of handling immensely complex circuits, yet these simulators are underutilized. Often the EM analysis is performed by a senior EM modeling expert. This type of work flow can make it ineffective for circuit designers to combine the expert’s electromagnetic results with their existing circuit simulations to characterize a complete system.
An even bigger challenge is multi-chip and multi-module design. Designers want to bring together IC’s using different technologies onto a single module. However, a lack of interoperability between products creates a gap: Chip, module, and interconnect layouts are often completed using different CAE tools, all with their own database. Even when a single environment is used, the best platforms still require some manual processes to combine electromagnetic, circuit, and system data into a meaningful complete simulation when analyzing complex, multi-technology designs.
Microwave CAE vendors are all working provide interface and interoperability features that match the sophistication of today’s simulators. Foundries are beginning to embrace standards . Most importantly, engineers are excited about the extra power that these new interfaces and standards will bring to their design flow.
The Future of Microwave CAE Software
CAE software has always followed the lead of the general consumer software market for usability improvements. The current generation of consumer software is adaptive, uses sophisticated visual effects, and aims for zero learning curve. Software giants have long realized that the key to their growth is expanding the size of the market by making their software usable by everyone.
One of the latest trends in user interface design is adaptability. Today’s consumer software interfaces anticipate what users might want to do and present options automatically. Some software even goes further and actually performs actions that it “thinks” the users will want to do. Automatic spelling or grammar correction is a simple example. By combining adaptability with nonstop visual feedback, today’s interfaces allow children to run game software that is more complex and has more functionality than any CAD program.
Similarly, today’s users of consumer software expect to move data from one application to another seamlessly. Documents which in the 1980s had to be transferred using finicky import/export processes are now available with a simple copy/paste or email attachment. Open standards are commonplace: HTML, PDF, MPEG, MIME, XML, SQL—the list goes on. Consumer software that is not compatible with standards does not do well in the marketplace. On the other hand, CAE software vendors tend to focus on raw technology and performance as a first priority, putting user experience second. This tendency goes well beyond just microwave CAE software and into the industry as a whole.
The lack of interoperability in PDK’s compounds this problem, forcing engineers to decide between using a single tool and risking difficulties during data transfer. As a result simulator technology still remains relatively underutilized despite all of the advances and technological breakthroughs, contributing to many of the manual processes that consume engineering time.
Now instead, picture a microwave CAE environment which uses an adaptive interface. This software would anticipate the next commands you might want and put them at your fingertips. When you are ready to simulate your design, you may discover that the software has already tried a few simulations (maybe a lot as parallel computing becomes mainstream) with combined EM, circuit, and system simulations just a mouse click away. The software works automatically with measurement hardware to verify overall design performance as you develop prototypes. Since this environment uses a common database with interoperable libraries, this interface continues seamlessly throughout your flow as you move IP from one vendor’s tool to another.
Fortunately, from my perspective, our CAE industry appears poised for some major advances in the next few years. Many companies, such my employer Agilent, are enhancing their products with these goals in mind. I encourage readers help shape these products by talking to their existing CAE vendor about their particular needs for interoperability and usability.
 "Non-Linear Simulation on Every Desktop," Microwave Journal, August 2000.
 "Integrated Software for Electromagnetic Simulation," Rob Lefebvre, Microwave Journal, November 1998, pp. 136-140.
 "The Current State of CAD - A Users' Perspective," Microwave Engineering Europe, November 1999.
 “Group’s ‘interoperable’ analog flow turns up heat on Cadence,” Mark LaPedus, EE Times, June 16, 2008.