Carver Mead | |
|---|---|
 Mead in 2002 | |
| Born | Carver Andress Mead (1934-05-01)May 1, 1934 (age 90) Bakersfield, California, U.S. |
| Awards | Kyoto Prize (2022) National Medal of Technology 2011BBVA Foundation Frontiers of Knowledge Award Computer History Museum Fellow (2002) |
| Scientific career | |
| Thesis | Transistor Switching Analysis (1960) |
| Doctoral advisor | R. D. Middlebrook Robert V. Langmuir |
| Doctoral students | Kwabena Boahen |
| External videos | |
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 | |
 Carver Mead, Winner of 1999 Lemelson-MIT Prize,Lemelson Foundation | |
| Carver Mead – Semiconductors, April 17, 2014, The Official ACM | |
| Carver Mead presents The Universe and Us: An Integrated Theory of Electromagnetics and Gravitation, TTI/Vanguard |
Carver Andress Mead (born 1 May 1934) is an American scientist and engineer. He currently holds the position of Gordon and Betty Moore Professor Emeritus of Engineering and Applied Science at theCalifornia Institute of Technology (Caltech), having taught there for over 40 years.[1]
A pioneer of modernmicroelectronics, Mead has made contributions to the development and design ofsemiconductors, digital chips, andsilicon compilers, technologies which form the foundations of modernvery-large-scale integration chip design. Mead has also been involved in the founding of more than 20 companies.[2]
In the 1980s, Mead focused on electronic modeling of human neurology and biology, creating "neuromorphic electronic systems."[3][4][5] Most recently, he has called for the reconceptualization of modern physics, revisiting the theoretical debates ofNiels Bohr,Albert Einstein and others in light of later experiments and developments in instrumentation.[6]
Mead's contributions as a teacher include the classic textbookIntroduction to VLSI Systems (1980), which he coauthored withLynn Conway. He also taughtDeborah Chung, the first female engineering graduate of Caltech,[7] and advised Louise Kirkbride, the school's first female electrical engineering student.[8][9]
Carver Andress Mead was born inBakersfield, California, and grew up inKernville, California. His father worked in a power plant at theBig Creek Hydroelectric Project, owned bySouthern California Edison Company.[6] Carver attended a tiny local school for some years, then moved toFresno, California to live with his grandmother so that he could attend a larger high school.[8] He became interested in electricity and electronics while very young, seeing the work at the power plant, experimenting with electrical equipment, qualifying for anamateur radio license and in high school working at local radio stations.[10]
Mead studiedelectrical engineering at Caltech, getting his BS in 1956, his MS in 1957, and his PhD degree in 1960.[11][12]
Mead's contributions have arisen from the application of basic physics to the development of electronic devices, often in novel ways. During the 1960s, he carried out systematic investigations into the energy behavior of electrons in insulators and semiconductors, developing a deep understanding ofelectron tunneling, barrier behavior andhot electron transport.[13] In 1960, he was the first person to describe and demonstrate a three-terminal solid-state device based on the operating principles of electron tunneling and hot-electron transport.[14] In 1962 he demonstrated that using tunnel emission, hot electrons retained energy when traveling nanometer distances in gold.[15] His studies ofIII-V compounds (with W. G. Spitzer) established the importance of interface states, laying the groundwork forband-gap engineering and the development ofheterojunction devices.[13][16][17][18]
In 1966, Mead designed the firstgallium arsenide gatefield-effect transistor using aSchottky barrier diode to isolate the gate from the channel.[19] As a material, GaAs offers much higherelectron mobility and highersaturation velocity than silicon.[20] TheGaAsMESFET became the dominant microwave semiconductor device, used in a variety of high-frequencywireless electronics, including microwave communication systems inradio telescopes, satellite dishes and cellular phones. Carver's work on MESFETs also became the basis for the later development ofHEMTs by Fujitsu in 1980. HEMTs, like MESFETs, are accumulation-mode devices used in microwave receivers and telecommunication systems.[20]
Mead is credited byGordon Moore with coining the termMoore's law,[21] to denote the prediction Moore made in 1965 about the growth rate of the component count, "a component being a transistor, resistor, diode or capacitor,"[22] fitting on a single integrated circuit. Moore and Mead began collaborating around 1959 when Moore gave Mead "cosmetic reject" transistors fromFairchild Semiconductor for his students to use in his classes. During the 1960s Mead made weekly visits to Fairchild, visiting the research and development labs and discussing their work with Moore. During one of their discussions, Moore asked Mead whether electron tunneling might limit the size of a workable transistor. When told that it would, he asked what the limit would be.[23]
Stimulated by Moore's question, Mead and his students began a physics-based analysis of possible materials, trying to determine a lower bound for Moore's Law. In 1968, Mead demonstrated, contrary to common assumptions, that as transistors decreased in size, they would not become more fragile or hotter or more expensive or slower. Rather, he argued that transistors would get faster, better, cooler and cheaper as they were miniaturized.[24] His results were initially met with considerable skepticism, but as designers experimented, results supported his assertion.[23] In 1972, Mead and graduate student Bruce Hoeneisen predicted that transistors could be made as small as 0.15 microns. This lower limit to transistor size was considerably smaller than had been generally expected.[24] Despite initial doubts, Mead's prediction influenced the computer industry's development of submicron technology.[23] When Mead's predicted target was achieved in actual transistor development in 2000, the transistor was highly similar to the one Mead had originally described.[25]
Mead was the first to predict the possibility of creating millions of transistors on a chip. His prediction implied that substantial changes in technology would have to occur to achieve such scalability. Mead was one of the first researchers to investigate techniques for very-large-scale integration, designing and creating high-complexity microchips.[26]
He taught the world's firstLSI design course, at Caltech in 1970. Throughout the 1970s, with involvement and feedback from a succession of classes, Mead developed his ideas of integrated circuit and system design. He worked withIvan Sutherland andFrederick B. Thompson to establish computer science as a department at Caltech, which formally occurred in 1976.[27][28] Also in 1976, Mead co-authored a DARPA report with Ivan Sutherland andThomas Eugene Everhart, assessing the limitations of current microelectronics fabrication and recommending research into the system design implications of "very-large-scale integrated circuits".[29]
Beginning in 1975, Carver Mead collaborated withLynn Conway fromXerox PARC.[26] They developed the landmark textIntroduction to VLSI systems, published in 1979, an important spearhead of theMead and Conway revolution.[30] A pioneering textbook, it has been used in VLSI integrated circuit education all over the world for decades.[31] The circulation of early preprint chapters in classes and among other researchers attracted widespread interest and created a community of people interested in the approach.[32] They also demonstrated the feasibility of multi-project shared-wafer methodology, creating chips for students in their classes.[33][34][35][36]
Their work caused aparadigm shift,[36] a "fundamental reassessment" of the development of integrated circuits,[26] and "revolutionized the world of computers".[37] In 1981, Mead and Conway received the Award for Achievement fromElectronics Magazine in recognition of their contributions.[26] More than 30 years later, the impact of their work is still being assessed.[38]
Building on the ideas of VLSI design, Mead and his PhD student David L. Johannsen created the firstsilicon compiler, capable of taking a user's specifications and automatically generating an integrated circuit.[39][40] Mead, Johannsen, Edmund K. Cheng and others formed Silicon Compilers Inc. (SCI) in 1981. SCI designed one of the key chips forDigital Equipment Corporation'sMicroVAX minicomputer.[40][41]
Mead and Conway laid the groundwork for the development of theMOSIS (Metal Oxide Semiconductor Implementation Service) and the fabrication of the firstCMOS chip.[38] Mead advocated for the idea offabless manufacturing in which customers specify their design needs to fabless semiconductor companies. The companies then design special-purpose chips and outsource the chip fabrication to less expensive overseassemiconductor foundries.[42]
Next Mead began to explore the potential for modelling biological systems of computation: animal and human brains. His interest in biological models dated back at least to 1967, when he met biophysicistMax Delbrück. Delbrück had stimulated Mead's interest intransducer physiology, the transformations that occur between the physical input initiating a perceptual process and eventual perceptual phenomena.[43]
Observing graded synaptic transmission in the retina, Mead became interested in the potential to treat transistors as analog devices rather than digital switches.[44] He noted parallels between charges moving in MOS transistors operated in weak inversion and charges flowing across the membranes of neurons.[45] He worked with NobelistJohn Hopfield and NobelistRichard Feynman, helping to create three new fields:neural networks,neuromorphic engineering, and thephysics of computation.[12] Mead, considered a founder of neuromorphic engineering, is credited with coining the term "neuromorphic processors".[3][5][46]
Mead was then successful in findingventure capital funding to support the start of a number of companies, in part due to an early connection withArnold Beckman, chairman of the Caltech Board of Trustees.[12] Mead has said that his preferred approach to development is "technology push", exploring something interesting and then developing useful applications for it.[47]
In 1986, Mead andFederico Faggin foundedSynaptics Inc. to develop analog circuits based in neural networking theories, suitable for use in vision and speech recognition. The first product Synaptics brought to market was a pressure-sensitive computertouchpad, a form of sensing technology that rapidly replaced the trackball and mouse in laptop computers.[48][49] The Synaptics touchpad was extremely successful, at one point capturing 70% of the touchpad market.[24]
In 1988,Richard F. Lyon and Carver Mead described the creation of an analogcochlea, modelling the fluid-dynamic traveling-wave system of the auditory portion of the inner ear.[50] Lyon had previously described a computational model for the work of the cochlea.[51] Such technology had potential applications in hearing aids, cochlear implants, and a variety of speech-recognition devices. Their work has inspired ongoing research attempting to create a silicon analog that can emulate the signal processing capacities of a biological cochlea.[52][53]
In 1991, Mead helped to form Sonix Technologies, Inc. (later Sonic Innovations Inc.). Mead designed the computer chip for their hearing aids. In addition to being small, the chip was said to be the most powerful used in a hearing aid. Release of the company's first product, the Natura hearing aid, took place in September 1998.[54]
In the late 1980s, Mead advisedMisha Mahowald, a PhD student in computation and neural systems, to develop thesilicon retina, using analog electrical circuits to mimic the biological functions ofrod cells,cone cells, and otherexcitable cells in the retina of the eye.[55] Mahowald's 1992 thesis received Caltech's Milton and Francis Clauser Doctoral Prize for its originality and "potential for opening up new avenues of human thought and endeavor".[56] As of 2001[update] her work was considered "the best attempt to date" to develop a stereoscopic vision system.[57] Mead went on to describe an adaptive silicon retina, using a two-dimensionalresistive network to model the first layer of visual processing in the outer plexiform layer of the retina.[58]
Around 1999, Mead and others establishedFoveon, Inc. inSanta Clara, California to develop new digital camera technology based on neurally-inspiredCMOS imagesensor/processing chips.[24] The image sensors in the Foveon X3 digital camera captured multiple colors for each pixel, detecting red, green and blue at different levels in the silicon sensor. This provided more complete information and better quality photos compared to standard cameras, which detect one color per pixel.[59] It has been hailed as revolutionary.[24] In 2005, Carver Mead,Richard B. Merrill andRichard Lyon of Foveon were awarded theProgress Medal of theRoyal Photographic Society, for the development of theFoveon X3 sensor.[60]
Mead's work underlies the development of computer processors whose electronic components are connected in ways that resemble biologicalsynapses.[46]In 1995 and 1996 Mead, Hasler, Diorio, and Minch presented single-transistor silicon synapses capable of analog learning applications[61] andlong-term memory storage.[62] Mead pioneered the use offloating-gate transistors as a means ofnon-volatile storage forneuromorphic and other analog circuits.[63][64][65][66]
Mead and Diorio went on to found the radio-frequency identification (RFID) providerImpinj, based on their work withfloating-gate transistors (FGMOS)s. Using low-power methods of storing charges on FGMOSs, Impinj developed applications forflash memory storage andradio frequency identity tags.[47][67]
Carver Mead has developed an approach he callsCollective Electrodynamics, in which electromagnetic effects, including quantized energy transfer, are derived from the interactions of the wavefunctions of electrons behaving collectively.[68] In this formulation, the photon is a non-entity, and Planck's energy–frequency relationship comes from the interactions of electroneigenstates. The approach is related toJohn Cramer'stransactional interpretation of quantum mechanics, to theWheeler–Feynman absorber theory of electrodynamics, and toGilbert N. Lewis's early description of electromagnetic energy exchange at zero interval[clarification needed] inspacetime.
Although this reconceptualization does not pertain to gravitation, a gravitational extension of it makes predictions that differ from general relativity.[69] For instance,gravitational waves should have a different polarization under "G4v", the name given to this new theory of gravity. Moreover, this difference in polarization can be detected by advancedLIGO.[70]
Mead has been involved in the founding of at least 20 companies. The following list indicates some of the most significant, and their main contributions.
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