Abstract—A low-energy successive approximation analog-todigital converter (ADC) targeted for use in distributed sensor networks is presented. The individual nodes combine sensing, computation, communications, and power into a tiny volume. Energy is extremely limited, forcing the nodes to operate with very low duty cycles. This paper describes the design and implementation of an ADC to meet the unique requirements of sensor networks. The ADC reported here consumes 31 pJ/8-bit sample at 1-V supply and 100 kS/s, with a standby power consumption of 70 pW. This energy consumption is one of the lowest ever reported. Index Terms—Analog-to-digital converter (ADC), charge redistribution, CMOS, energy, low power, sensor networks, Smart Dust, successive approximation.

Date Approved: August 23, 2011Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius-- and a lot of courage-- to move in the opposite direction.-- Albert EinsteinTo all my sweet family and my beloved wife with the most gratitude that I feel stuck that I cannot show it enoughACKNOWLEDGEMENTS I would first like to express the most gratitude to my advisor, Prof. John Barry, for his encouragement and support during my time at Georgia Tech. He not only has brightened the way when I was totally lost in finding a lighthouse for my research, but also has continuously inspired me with the guidance for my life. I deeply appreciate every opportunity I had to speak with him and learn from him in person. I learned a lot from his rigorous thought process in defining problems, modeling systems, and solving the problems, which will affect me in one way or another throughout the rest of my research activities. I am also indebted to my co-advisor, Prof. Paul Hasler, who has guided me with his invaluable insights on circuit implementation aspects. Being able to be involved in actual circuit implementation was a great advantage for me to maintain a close distance from practical issues. His advice and directions meant a lot to me whenever I was struggling with