No time for boredom now. Three times a year, Ritchey takes a leave of absence from 3Com to teach a popular course on high-speed design at the PCB Design
Conferences in California, Massachusetts, and Asia. He also teaches University of California (U.C.) at Berkeley extension classes in various cities. Ritchey has written around 100 articles for trade publications and is
trying to finish a textbook.Every once in a while, Ritchey manages to get far away from it all, by backpacking in a favorite place such as the Grand Canyon or sailing around San Francisco Bay. But he's a long way
from the retirement he envisioned in 1992.
One reason for all the activity is that Ritchey is in exactly the right place at the right time. Fast IC edge rates and wide data buses are bringing with them a host of
signal-integrity problems, forcing board designers to understand issues such as crosstalk and reflections. And this year, Ritchey said, ground bounce related to IC packages has become a serious problem.
Designers thus
need to get up to speed quickly on electrical issues and learn to run signal-integrity analysis tools. In many cases, that practically means going back to school. And it's not only board designers who need remedial
education, Ritchey said, but also many degreed engineers.
"We as an industry have spent the last 20 years graduating computer-science people where the focus was on logical design," Ritchey said. "That was possible
because we had slow logic, and it was basically connect the dots. We really do have a generation of engineers who have not taken such courses as fields and waves, and who don't even know how an electromagnetic wave
behaves."
Ritchey's classes are a "leading draw" at the PCB Design Conferences, said Pete Waddell, conference chairman. "Designers have to get more into theory, and Lee is good at teaching them in a language they can
understand," he said.
"Lee is seen as an expert in his field," said Dave Kohlmeier, president of signal-integrity tool provider HyperLynx (Redmond, Wash.). "He teaches a lot of classes at trade shows. We routinely
give him early views of our products so he can get our feedback, and he's really good about that."
A lot of on-the-job teaching takes place at 3Com, where Ritchey serves as "corporate trainer" and consultant on
high-speed design. "I drive some of the simulation tools, but I spend more time teaching design teams how to figure out the design process and the design rules," he said. I'm working my way around, division by division,
to set up groups to do things like signal-integrity analysis."
3Com has several different groups doing board design, in such locations as Boston, Israel, and the United Kingdom, in addition to Santa Clara. In some,
Ritchey said, there's a clear separation between engineers and layout designers; in those that tend to ward high-speed design, that distinction is becoming less clear. There's a specialized group in Boston that runs
most of the ingnal-integrity tools.
With its work in Gigabit Ethernet and ATM switching, 3Com designs some demanding boards. How fast does it get? "Data rates on a single wire are 600 Mbits per second, buses are 5
Gbits per second, and some boards are switching at 24 Gbits per second," said Ritchey. "Outrageous stuff -- and this is not considered fast enough. It's crazy!"
Until recently, he said, cross-coupling and reflections
were the two primary problems, but two new ones have arisen this year. First, Ritchey said, "we are dying from ground bounce and Vcc problems related to the package." Second, Ritchey said, 3Com is "struggling" with
power-supply bypassing, which is important in electromagnetic interference avoidance.
The new problems force Ritchey to get more involved with IC-package analysis. That may or may not be a big challenge, depending on
who's providing the parts.
"We fit quite a few ASICs from IBM, we can usually count on them to have pre-done all the signal-integrity work around the package choice," said Ritchey. "The prblem is places that don't
have that level of technical skill -- and that's just about everyone else."
While Ansoft (Pittsburg) and others provide tools that can analyze ground bounce in packaging, Ritchey currently subcontracts this kind of
analysis, because it's so specialized. The subcontractors run 3-D field analyses to calculate parasitic inductances of packages, and provide data that 3Com designers can use to modify board layouts.
Ritchey handles
the power-supply-by-passing problem himself. He determines the frquency that the circuit is going to demand from the power subsystem, uses MathCAD or Spice to model capacitance in the power supply, and considers the use
of decoupling capacitors. "I'm pretty much the only ne doing it, but I'm teaching the other engineers. We're getting pretty good correlation," he said.
Ritchey has a broad suite of tools for his other signal-integrity
analysis work. He uses HyperLynx tools for transient analysis, Ansoft's 2-D field solver, and CAD-Migos (Redwood City, Calif.) analog simulation tools, among others. He doesn't run board-layout tools himself, but noted
that most 3Com designers are using Allegro from Cadence Design Systems (San Jose, Calif.).
One very significant development this year, said Ritchey, is that the tools have gotten easier to use. Decisions by vendors
such as Ansoft to provide PC-based tools has been a major part of that development.
"Basically we had all the characteristics one sees in that kind of tool," Ritchey said. "A poor GUI, and it takes forever to learn
which button to push." Further, he siad, UNIX price tags pushed tools out of the reach of the average designer.
Ritchey had been telling his classes that a 2-D field solver was the right way to go, but the tools just
aren't accessible. Suddenly this spring, he said, he heard from four suppliers who said their tools now run on PCs and who wanted to show him their wares. "These vendors don't want me to say in my class their tools
don't work, so they're bending over backwards to make sure I know what they do," Ritchey said. "I'm not trying to put anything down -- I just have to tell it like it is. Maybe the best thing I've got going in these
classes is influencing improvement in tools."
HyperLynx has long specialized in easy-to-use, PC-based signal-integrity tools. But Kohlmeier acknowledged that most of HyperLynx' tools are still used by signal-integrity
experts. The company has done a lot of work with "wizards" that help simplify the process -- but even so, Kohlmeier noted, "we still have a long ways to go."
Educating the designer
Getting signal-integrity
tools into the hands of the average board designer will require the very kind of educational mission that Ritchey is pursuing. "Getting them to use the tools doesn't take very long," he said. "The problem is having the
techinical skill to realize what the feed the tool, and recognize whether the tool is making logical sense. That requires some understanding of the physics of what's happening."
What board designers need, Ritchey
said, is a clear understanding of the electrical engineering that's going on, especially the behavior of components. There are two distinct reactions, he said. "One group is not going to learn this new stuff, and they
become realtors. The other group sees it as a challenge and wants to know where they can get classes."
Ritchey's classes at the PCB Design Conferences are aimed at board designers, and provide a day of intense
instruction on the fundamentals of electronics, the behavior of components, and board layout and fabrication. Students rate the classes on a scale from zero to five. Ritchey received cumulative ratings of 4.9 or 5.0 for
two recent classes. "I can't believe how good the feedback is," he said.
For U.C. Berkeley classes, however, Ritchey is mostly teaching engineers. He finds that they, too, need instruction on such topics as how
transmission lines operate, and how problems such as coupling, reflections and ground bounce occur. He also gives them an introduction to the board-design process.
Ritchey's teaching career actually started at Shared
Resources, where he found himself conducting half-day and one-day classes on electronic fundamentals for board-design clients. Shared Resources was a Silicon Valley company that offered design services to minicomputer
companies, and sold a pc-board CAD system for high-speed design called Crystal. The company no longer exists, but Ritchey said Crystal is still in use at a few companies.
Ritchey received his BSEE from Sacramento
State. He went on to U.C. Berkeley in 1957 but, ironically, was kicked out of the school he now teaches for. "They apparently didn't see the humor in water fighting," Ritchey said. "It was a real water fight."
After
designing satellites for Ford Aerospace, and working for a half-dozen startups including Amdahl Computer, Ritchey first got into board design at Magnuson Computer in 1978. That was when the young company discovered its
survival depended on getting some boards developed in a hurry.
"Right now, there's a lot of startup fever," Ritchey noted. "Everyone is trying to be the next Apple or 3Com or Cisco or Intel. I enjoyed it all -- but
boy, I wouldn't do it again!"
Back to Top
