Cobo Yepes, Nicolas
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Publication A method for fault diagnosis of embedded systems via At-Speed (IDDA) current testing(2015) Cobo Yepes, Nicolas; Palomera-García, Rogelio; College of Engineering; Jimenez Cedeño, Manuel; Ducoudray-Acevedo, Gladys O.; Department of Electrical and Computer Engineering; Cáceres-Valencia, Pablo G.This thesis presents the development of a test method for diagnosing the presence of embedded systems failures caused by physical defects in the printed circuit board and electronic components. Specifically, the proposed methodology includes a set of topics and procedures required, including topics such as identifying embedded systems modules, test block design, measurement equipment configuration and results analysis. The effectiveness of this approach to identify catastrophic and parametric failures was evaluated using three embedded systems with similar topologies but different electrical designs, using components from different manufacturers and different feature to meet the requirements of experimental design methodology. The execution of the measurement is performed with a non-invasively current sensor designed to manage the delivery of pulses in the power supply lines of the device under test (DUT) and at the same time it measures the consumption of the demand the embedded system. The analysis of the results reveals a large percentage of detected flaws and patterns of similar behavior in the tested systems.Publication On-chip power management unit for multi-band ambient RF energy harvesting oriented to IOT and WSN applications(2021-05-10) Cobo Yepes, Nicolas; Palomera-García, Rogelio; College of Engineering; Serrano-Rivera, Guillermo; Ducoudray-Acevedo, Gladys O.; Rodríguez-Solís, Rafael A.; Department of Electrical and Computer Engineering; Cáceres-Duque, Luis F.Several attempts have been made to reduce or eliminate the use of batteries in remote electronic applications such as IoT and WSN nodes. However, most designs are constrained to operate under very specific conditions, and an appropriate system that can operate in different environments or less restrictive conditions is still to be designed. Optimization is required throughout the process of capturing, storing, and delivering, in order to use the energy from the environment in form of RF signals. Most of the previous works present a fault pattern that avoids reaching this objective, as is the focusing only in the part of the antenna design with a basic power management circuit. This gives rise to another of the main challenges that is to avoid the use of discrete diodes that define a high threshold voltage requirement as well as the approach of feeding the application continuously. This research proposes the design of a new RF energy harvester on-chip to manage and optimize the way in which energy is scavenged and delivered to the load. Considering power levels and frequencies available in an urban and suburban environment, and the demand in the consumption of the device to be feed. Finally, a design capable of working with input powers up to -38dBm, receiving four bands from 1.68GHz to 2.47GHz, a max voltage conversion efficiency of 69, a Vout up to 4.1V, and independent of the load impedance was achieved.