Zero-Crossing-Based Ultra-Low-Power A/D Converters |
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Authors: | Lee H-S Brooks L Sodini C G |
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Affiliation: | Massachusetts Institute of Technology, Cambridge, United States; |
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Abstract: | Since the first demonstration of a comparator-based switched-capacitor circuit, analog-to-digital (A/D) converters based on virtual ground detection have made steady and significant progress. Comparators have been replaced by zero-crossing detectors, leading to the development of zero-crossing based circuits for faster speed and lower power. All facets of performance including the sampling rate, effective number of bits, noise floor, and figure-of-merit have improved substantially. This paper focuses on recent implementations of zero-crossing based A/D converters and discusses the technical issues unique to these A/D converters as well as solutions that have been developed to improve their performance and practicality. A series of prototype designs whose performance ranges from 8 bit, 200 MS/s to 12 bit, 50 MS/s are described. The ultimate low power potentials of these A/D converters are compared with various different types of complementary metal–oxide–semiconductor A/D converters from a fundamental thermal noise standpoint. |
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