Vittoz Recognized for Pioneering Contributions to Low-Power Device Modeling and CMOS Circuit Design

The 2004 IEEE Solid-State Circuits Technical Field Award will be awarded to Eric Vittoz for “for pioneering contributions to low-power device modeling and CMOS circuit design.”

VIttoz, a Chief Scientist with CSEM(Centre Suisse d Électronique et de Microtechnique SA), has made important contributions to the low-power, low-voltage CMOS analog design field and to the modeling of CMOS devices for a wide range of applications. In the early part of his work, Vittoz developed circuits for low-power signal processing in digital watches. This work included both analog and digital circuits required to perform the watch function. Because of the expected higher yield of MOS technology, CMOS was chosen for these chips. For very low power operation, the circuits were going to operate at very low voltages, where the MOS transistors never completely turned on. To evaluate these circuits, new MOS device models had to be constructed that described the sub-threshold “bipolar-like” behavior of the MOS device. His work in modeling sub-threshold CMOS operation for analog applications led to many fundamental, widely referenced papers on this subject. Together with Christian Enz and François Krummenacher, he created the EKV CMOS device model that is widely used today. This model is extremely accurate over the whole operation range of the MOS transistor.

In addition to his device modeling work, he has made numerous contributions to low-power circuits. For example, in watches, extremely accurate crystal oscillator circuits are needed. Vittoz made contributions to both the theory and application of these oscillators. As a result of his work, a tutorial paper was published paying particular attention to the phenomenon of phase jitter, which is important to the accuracy and stability of oscillators. In watches long-term stability is very important, unlike in sampling clock generation, where short-term jitter needs to be known.

Eric Vittoz also made significant contributions to microwatt switched capacitor circuits for applications in amplification and filtering functions. Many of his practical contributions in this field have been presented at workshops and conferences, including the modeling of switches and the charge feed through introduced by these devices.
Another example is his work on how to use a bipolar transistor in a CMOS process to create a stable bandgap reference. He introduced “lateral” bipolar transistors into CMOS technology to obtain bandgap voltage reference circuits with very good temperature stability. Matching performance of bipolar devices is much better than that of MOS devices, and the exponential character of the bipolar transistor is very suitable for the implementation of bandgap reference current sources.

“The modeling work Vittoz did was noteworthy,” recalls Jim McCreary of Xicor. “Although bandgap references in CMOS already existed at that time, Vittoz demonstrated that at low bias voltages the drain current was exponential with gate voltage much like a bipolar device. As a result they could be used to emulate a bandgap reference. But the KT/q dependence needed a slope modifier.” Although McCreary notes that CMOS bandgap references today do not use this technique,Vittoz did originate the bipolar bandgap reference on CMOS chips.

Yannis Tsividis of Columbia University writes, “Eric is a true pioneer. He has taken what used to be considered an undesirable, ‘leakage’ region of MOS transistor operation - weak inversion - and has turned it into a region in which more and more circuits are designed today. He has changed the face of low-power electronics, and he has done so in an unusually broad way, spanning the field from devices to circuits to systems and applications.”

Vittoz received his EE degree from Polytechnical School University of Lausanne in 1961 and his PhD from EPFL (Swiss Institute of Technology Lausanne) in 1969. He joined the Centre Electronique Horloger (CEH) in May 1962, became head of the Advanced Circuits Department at CEH in 1967 and was appointed Vice Director and head of the Applications Division of CEH in 1971. CSEM (Centre Suisse d Électronique et de Microtechnique SA) was founded in 1984 and Vittoz took over as the first Vice President and head of the ASIC design center until 1997 when he became Executive Vice President of the Microelectronics Division. In 1999 he partially retired from CSEM with the position of Chief Scientist. Since 1975, he has been lecturing and supervising undergraduate and graduate students who are working on projects in analog circuit design at EPFL. In 1982 he became a professor at EPFL.

Vittoz is a Fellow of the IEEE and served as an SSCS AdCom member from 1996 to 1999. Vittoz was involved in the formation of the one of the IEEE Solid-State Circuits Society. He also is a member of the steering committee of ESSCIRC, the European Solid-State Circuits Conference, for which the SSCS provides technical cosponsorship.

Vittoz holds more than 25 U.S. patents and has authored more than 36 IEEE publications. In 1994 he presented the plenary talk at the ISSCC titled “Low-power design: Ways to approach the limits.” He also also given numerous Short Courses at the conference over the years and is well known for his contributions to Analog Design Courses of MEAD, Eurochip, and Iberchip.