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.

A successive approximation ADC targeted for use in distributed sensor networks is presented. The individual nodes in these sensor networks are very energy constrained. Typical use of the individual nodes will include long periods of idle time in a low power standby mode followed by a period of activity that may include sampling of the sensors, computation, and communication. The ADC reported here consumes only 3.1 µW, resulting in 31 pJ/8-bit sample at 1V supply with a maximum sampling rate slightly over 100 kS/s. The standby power consumption at 1 V supply is 41 pW. The µ-power consumption makes this one of the lowest power ADCs ever reported. 1.