Electronic Design

Carver Mead: A Trip Through Four Eras Of Innovation

Mead (2004)

Largely due to a little boy's trips with his dad to a power plant, today we can enjoy digital cameras with high-quality photos, touchpad screens, fast and clear telecommunications, video recorders, the Internet, and tons of other technological inventions based on affordable, integrated-circuit chip designs and neural circuitry.

That little boy was Carver Mead. He now holds more than 50 U.S. patents, has authored 100-plus scientific papers, and is a pioneer in solid-state electronics, a revolutionary in the design of very large-scale integrated (VLSI) circuits, and a teacher to many creators of today's high-tech tools, systems, and gadgets. In 2003, Mead received the National Medal of Technology Award and the National Academy of Engineering Founders Award for visionary contributions to the field of microelectronics.

Now 70, Carver looks back on his life and identifies four eras of significant contribution. The first involves "device physics." This included his work on "the guts of what makes transistors work." In 1965, he built the first gallium-arsenide (GaAs) MESFET, now a mainstay of wireless electronics. The metal-semiconductor field-effect transistor (MESFET) uses a conducting channel positioned between a source and drain contact region.

This GaAs transistor developed into the HEMT, a high electron mobility transistor. The universal amplifying device is used in microwave transmitters and receivers for cell phones as well as telecommunication systems, and it's an integral component of the Internet.

He and his students predicted in 1972 that transistors could be made as small as 0.15 microns—much, much smaller than the existing 10 microns. The prediction, based on physics-based analysis, drove the industry to submicron technology. In 2000, when that prediction came true, the transistor that emerged was nearly identical to the one Mead described nearly 30 years earlier.

The next stage, the VLSI era, emerged in the 1970s. What resulted was a new view of the microchip computer-aided design. In 1980, Mead and Lynn Conway co-authored Introduction to VLSI Systems, which quickly became the leading engineering textbook in the design of complex circuitry at the microscopic level. Classes in VLSI design sprung up in most leading universities, and, in turn, a whole wave of new "fabless semiconductor" companies emerged. This new industry segment designs complex, special-purpose chips that are fabricated in silicon foundries.

Then Mead changed directions and teamed with Professor John Hopfield and Nobelist Richard Feynman to pioneer work in neural networks, neuromorphic engineering, and physics of computation. Mead examined the nervous system, how animal brains compute, and how we hear, see, and learn. His laboratory showed that analog circuits could emulate the basic operations of the human nervous system. That led to the neuromorphic systems stage of his life and the creation of the first neurally inspired chips.

"These systems take their inspiration from the way portions of the brain work," says Carver. "For example, there are a lot of things going on in a retina. It's not just a passive sensor."

From this research came active pixel imaging chips, the cochlear chip modeled after human hearing, and chips that learn from experience as we do. Today's digital hearing aids are one of the products to result from Mead's neuromorphic work. From this work, Mead co-founded Synaptics, the leading manufacturer of touchpad systems; Sonic Innovations, the leading provider of digital hearing aids; and in 1997, founded Foveon, producer of high-fidelity digital imaging systems.

In the fourth era, Mead spent his time writing his book Collective Electrodynamics. Mead views that work as "By far the best science (he has) ever done. It shows how all the laws of electromagnetism arise naturally from the quantum nature of the electron."

Mead is now on "permanent sabbatical" from teaching at Caltech, where he is still the Gordon and Betty Moore Professor of Engineering and Applied Science, Emeritus. He's not on a sabbatical from learning, though. One could say he has entered a fifth era. "Electricity is the enabling technology of modern civilization," he says. "My wife and I are very interested in how the world became electrified. It's a great story that has not been told."

Together they're researching its technical history. "That's a lot of fun," says Mead. "We read the old journal articles, visit old power plants, trace abandoned power lines, and track down people's grandchildren, because they may have the last remaining hints as to how things happened. It's all about people. It's people who have the insights, and until you chase that down, you don't have the story."

Mead's passion has always been to inspire and excite students about technology. He shared his excitement with students since receiving his MSEE in 1957 from the California Institute of Technology. "Technology is exciting. It's fascinating. I spent my whole career trying to open the world of technology to students," says Mead. Among his students were the founders of more than 100 high-tech companies.

Looking back on his times of going to the power plant with his Dad, Mead says, "I wish the same for every child. I wish that they could get close to something technological. Once you get a true intuitive understanding versus a surface explanation, it is exciting.I spent my whole career trying to open the world of technology to students. I would love to leave the world with a more intuitive understanding of science and technology. It is wonderful when students get it. We owe our modern civilization to the ones who do get it."

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