Although the basic concept of switched-capacitor circuits was envisioned by James Clerk Maxwell in 1873 in his A Treatise on Electricity and Magnetism, it lay dormant for nearly a century until David L. Fried’s 1972 IEEE JSSC paper: Analog Sampled-data Filters. The techniques were introduced to the semiconductor industry in 1976 owing to the visionary research of Profs. David A. Hodges, Paul R. Gray and Robert W. Brodersen at UC Berkeley and their identification of the killer “app”—the conversion of the telephone system from analog to digital. Consequently, the switched-capacitor technique has been used in high-volume data converters and signal processing ICs for nearly four decades. It is also critical to RF transceiver circuits and future killer applications including massive MIMO radios, biomedical circuits and systems, brain-machine interfaces, etc.
Despite its middle age, the field of CMOS analog and RF integrated circuits is entering a new era of energy-efficient/energy-harvested swarms of sensors, hundreds of communication devices per human, etc., associated with the Internet-of-Things vision. Future mixed-signal systems will be designed using advanced FINFET or SOI processes in addition to conventional CMOS technologies. Switched-capacitor circuits along with the emerging ring amplifier techniques are critical to implementing this vision. Some examples relating to the IOT vision will be described in this talk including efficient data compression and power transmission as well as advanced signal processing techniques using n-path techniques along with ring-amplifier structures.