A Mind for All Seasons

It is always fascinating to follow (and learn from) the scientific contributions of an accomplished researcher, particularly so when one works in the same area. Over four decades, Yannis Tsividis has made substantial contributions to circuits and systems at several levels: device modeling, circuit simulation methods, integrated circuit design, and signal processing techniques?each one an area on which an entire academic career could possibly be spent. During his PhD and for several years thereafter, he contributed to several IC designs, starting from the first integrated MOS opamp. Then, while investigating bandgap references and starting to write a book on circuits, he made his foray into device modeling, mainly of the MOS transistor. This work, spanning seven years culminated in the famous book, Operation and Modeling of the MOS Transistor, now in its third edition. Around the late seventies, switched-capacitor filters began finding widespread use in the telecom industry. Yannis started investigating analysis methods for switched-capacitor networks which eventually resulted in SWITCAP, a popular and highly efficient tool for simulating switched capacitor circuits. In the early 1980s, he began working on continuous-time filters?an area that received bulk of his attention for the next two decades. In the last decade, he has been investigating continuous-time digital signal processing, wherein analog signals are quantized and processed without being sampled. This has led to a number of techniques and offshoots into other areas of electronics.