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dc.contributor.advisorLeón-Salas, Walter D. (Walter Daniel)eng
dc.contributor.authorGhosh, Suvradipeng
dc.date.issued2013eng
dc.date.submitted2013 Falleng
dc.descriptionTitle from PDF of title page, viewed on April 2, 2014eng
dc.descriptionDissertation advisor: Walter D. Leon-Salaseng
dc.descriptionVitaeng
dc.descriptionIncludes bibliographic references (pages 171-183)eng
dc.descriptionThesis (Ph. D.)--School of Computing and Engineering and the Dept. of Physics & Astronomy. University of Missouri--Kansas City, 2013eng
dc.description.abstractThis dissertation focuses on the problem of increasing the lifetime of wireless sensors. This problem is addressed from two different angles: energy harvesting and data compression. Energy harvesting enables a sensor to extract energy from its environment and use it to power itself or recharge its batteries. Data compression, on the other hand, allows a sensor to save energy by reducing the radio transmission bandwidth. This dissertation proposes a fractal-based photodiode fabricated on standard CMOS process as an energy harvesting device with increased efficiency. Experiments show that, the fractal based photodiodes are 6% more efficient compared to the conventional square shaped photodiode. The fractal shape photodiode has more perimeter-to-area ratio which increases the lateral response, improving its efficiency. With increased efficiency, more current is generated but the open-circuit voltage still remains low (0:3V - 0:45V depending on illumination condition). These voltages have to be boosted up to higher values if they are going to be used to power up any sensory circuit or recharge a battery. We propose a switched-inductor DC-DC converter to boost the low voltage of the photodiodes to higher voltages. The proposed circuit uses two onchip switches and two off-chip components: an inductor and a capacitor. Experiments show a voltage up to 2:81V can be generated from a single photodiode of 1mm2 area. The voltage booster circuit achieved a conversion efficiency of 59%. Data compression was also explored in an effort to reduce energy consumption during radio transmission. An analog-to-digital converter (ADC), which can jointly perform the tasks of digital conversion and entropy encoding, has also been proposed in this dissertation. The joint data conversion/compression help savings in area and power resources, making it suitable for on-sensor compression. The proposed converter combines a cyclic converter architecture and Golomb-Rice entropy encoder. The converter hardware design is based on current-mode circuits and it was fabricated on a 0:5 m CMOS process and tested. Experiment results show a lossless compression ratio of 1:52 and a near-lossless compression of 5:2 can be achieved for 32 32 pixel imageeng
dc.description.tableofcontentsAbstract -- Illustrations -- Tables -- Acknowledgements -- Introduction -- Background -- Photodiode theory and experiment -- Lateral capacitance -- Boost converter -- Cyclic ADC and entropy encoder -- Conclusion -- Reference listeng
dc.format.extentxvi, 184 pageseng
dc.identifier.urihttp://hdl.handle.net/10355/41509eng
dc.subject.lcshComputer scienceeng
dc.subject.lcshWireless sensor networkseng
dc.subject.lcshWireless communication systemseng
dc.subject.lcshEnergy conversioneng
dc.subject.lcshData compression (Telecommunication)eng
dc.subject.lcshEnergy harvestingeng
dc.subject.otherDissertation -- University of Missouri--Kansas City -- Engineeringeng
dc.subject.otherDissertation -- University of Missouri--Kansas City -- Physicseng
dc.titleEnergy and Data Conversion Circuits for Low Power Sensory Systemseng
dc.typeThesiseng
thesis.degree.disciplineElectrical and Computer Engineering (UMKC)eng
thesis.degree.disciplinePhysics (UMKC)eng
thesis.degree.grantorUniversity of Missouri--Kansas Cityeng
thesis.degree.levelDoctoraleng
thesis.degree.namePh. D.eng


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