Distributed sensor networks, human body implants, and hand-held electronics have tight energy budgets that necessitate low power circuits. Most of these devices include an analog-to-digital converter (ADC) to process analog signals from the physical world. We describe a new topology for an asynchronous analog-to-digital converter, dubbed LCF-ADC, that has several major advantages over previously-designed ADCs, including reduced energy consumption and/or a simplification of the analog circuits required for its implementation. In this paper we describe the design of the LCF-ADC architecture, and present simulation results that show low power consumption. We discuss both theoretical considerations that determine the performance of our ADC as well as a proposed implementation. Comparisons with previously designed asynchronous analog-to-digital converters show the benefits of the LCF-ADC architecture. In 180 nm CMOS, our ADC is expected to consume 43 ?W at 160 kHz, and 438 ?W at 5 MHz.