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Representative of Graduate Studies
, 2005
"... The continued drive toward technology scaling in VLSI design has provided greater integration levels in silicon chips. Thanks to the reduction in minimum feature size and the corresponding decrease in power supply voltage, digital circuits have bene-fited from savings in area and power consumption. ..."
Abstract
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The continued drive toward technology scaling in VLSI design has provided greater integration levels in silicon chips. Thanks to the reduction in minimum feature size and the corresponding decrease in power supply voltage, digital circuits have bene-fited from savings in area and power consumption. This approach presents a number of challenges in Complementary Metal-Oxide Semiconductor (CMOS) analog circuit design. As the gate oxide of transistors becomes thinner and power consumption increases, a lower supply voltage must be used, even though it results in performance degradation of analog circuits. This must be done in order to avoid silicon punch-through. In applications requiring low power consumption and moderate conversion speed, one of the most frequently used analog-to-digital converter (ADC) architec-tures is the successive approximation. As data converters are mixed-signal circuits, containing both analog and digital circuits, they suffer from the same problems just described. This thesis presents the design of a low-voltage successive approximation ADC based on a Switched Opamp comparator. The proposed comparator archi-
MEMS sensors and wireless telemetry for distributed systems
, 1998
"... Further author information -- C. L. B. for the collaboration (correspondence) Email: brittoncl@ornl.gov, Telephone: (423) 574-1878. Selectively coated cantilevers are being developed at ORNL for chemical and biological sensing. The sensitivity can exceed that of other electro-mechanical devices as ..."
Abstract
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Further author information -- C. L. B. for the collaboration (correspondence) Email: brittoncl@ornl.gov, Telephone: (423) 574-1878. Selectively coated cantilevers are being developed at ORNL for chemical and biological sensing. The sensitivity can exceed that of other electro-mechanical devices as parts-per-trillion detection can be demonstrated for certain species. We are now proceeding to develop systems that employ electrically readable microcantilevers in a standard MEMS process and standard CMOS processes. One of our primary areas of interest is chemical sensing for environmental applications. Towards this end, we are presently developing electronic readout of a mercury-sensitive coated cantilever. In order to field arrays of distributed sensors, a wireless network for data reporting is needed. For this, we are developing on-chip spread-spectrum encoding and modulation circuitry to improve the robustness and security of sensor data in typical interference- and multipath-impaired...

