Benton H. Calhoun elected IEEE Fellow for pioneering design of ultra-low-power circuits
Three generations of battery-less sensor nodes harvest energy from their environment
The Institute of Electrical and Electronics Engineers has elected Benton H. Calhoun as a fellow for original and fundamental contributions in integrated circuit design. Calhoun, professor of electrical and computer engineering at the University of Virginia, specializes in energy-efficient, sub-threshold circuit design and applications that enable self-powered wireless sensing systems. These wireless sensing nodes are so low power that they no longer need to use batteries. Instead, they operate on power harvested from their environment.
Calhoun debuted a fully integrated self-powered wireless sensor node in 2012, in collaboration with Brian Otis, associate professor of electrical engineering at the University of Washington. Their wearable bioelectric monitor runs exclusively on energy harvested from body heat, consuming only 19 microwatts to keep itself running while taking an EKG and sending the results over a radio.
Calhoun’s and Otis’ self-powered system-on-chip kickstarted both a commercial venture and a national effort to innovate energy harvesting systems. Calhoun co-founded Everactive, Inc., initially named PsiKick, with David Wentzloff, University of Michigan associate professor of electrical engineering and computer science, and Brendan Richardson, a venture capital specialist and faculty member of the UVA McIntire School of Commerce. Everactive’s first product is a full-stack remote monitoring solution for industrial “internet of things” applications, composed of self-powered wireless sensors streaming data to the cloud for analysis and decision making. Released in December 2018, the platform reaches thousands of battery-less nodes deployed across multiple Fortune 100 customers.
Pursuing a community-wide research endeavor to enable self-powered wearable sensors and drawing heavily from Calhoun’s breakthrough circuit design, the National Science Foundation chartered a new program in 2012 to establish a multi-university Nanosystems Engineering Research Center for Advanced Self-Powered Systems of Integrated Sensors and Technologies. Calhoun serves as technical thrust leader for low-power systems-on-chip and UVA’s campus director.
Calhoun’s research contributions have produced tangible evidence of impact academically as well as commercially. He has successfully graduated 20 doctoral students from the University of Virginia and has over 220 peer-reviewed publications; he is quick to credit his many talented students as fundamental contributors to all of these innovations for sub-threshold circuits and self-powered wireless sensors.
Sub-threshold design refers to operating CMOS transistors with a supply voltage lower than their threshold voltage. In this state, the transistor is “off,” but continues to enable digital operation using leakage current, which Calhoun describes as analogous to doing useful work with drips of water from a leaking faucet. The design reduces energy consumption by over ten times and shows how memory and digital circuits can overcome variations in process parameters, voltage, and temperature to ensure reliable operation.
Calhoun’s successful demonstration of sub-threshold static random access memory launched a rich sub-field and resulted in the invention of numerous new bitcell topologies and low-power memory design incorporated in today’s academic and commercial chips.
The Institute of Electronics and Electrical Engineers is a leading professional association for advancing technology for humanity. Through its 400,000 plus members in 160 countries, the association is a leading authority on a wide variety of areas ranging from aerospace systems, computers, and telecommunications to biomedical engineering, electric power, and consumer electronics.
The board of directors confers the grade of fellow on members with an outstanding record of accomplishment in a field of interest. The total number of fellows elected in any one year cannot exceed one-tenth of one-percent of the Institute’s total voting membership. The technical community recognizes this highest grade of membership as a prestigious honor and an important career achievement.