Diseño de bloques analógicos para aplicaciones biomédicas usando resistores de alto valor
The realization of analog filters for very low frequencies (< 100Hz) completely integrated in silicon is considered a design challenge, since a low cutoff frequency implies a large RC time constant. For its realization a high value resistor (G Ω) or a high value capacitor (nF) is required. Howeve...
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| Tipo de recurso: | tesis de maestría |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2019 |
| País: | México |
| Institución: | Instituto Nacional de Astrofísica, Óptica y Electrónica |
| Repositorio: | Repositorio Institucional del INAOE |
| Idioma: | español |
| OAI Identifier: | oai:inaoe.repositorioinstitucional.mx:1009/1826 |
| Acceso en línea: | http://inaoe.repositorioinstitucional.mx/jspui/handle/1009/1826 |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/Inspec/Pseudo-resistor info:eu-repo/classification/Inspec/MOS info:eu-repo/classification/Inspec/Sub-threshold info:eu-repo/classification/Inspec/Low power info:eu-repo/classification/Inspec/Analog filters info:eu-repo/classification/Inspec/Low frequency info:eu-repo/classification/Inspec/Filter rejects band info:eu-repo/classification/cti/1 info:eu-repo/classification/cti/22 info:eu-repo/classification/cti/2203 |
| Sumario: | The realization of analog filters for very low frequencies (< 100Hz) completely integrated in silicon is considered a design challenge, since a low cutoff frequency implies a large RC time constant. For its realization a high value resistor (G Ω) or a high value capacitor (nF) is required. However, in integrated circuits the values of R and C fail to reach these values because they are limited to the range of M Ω (with low degree of accuracy) and tens of pF with a considerable consumption of silicon area. This work presents different circuits that can emulate the behavior of resistors that reach very high values (also called Pseudo-Resistors (PRs)). The main idea of these circuits is to use the MOS transistor operating in subthreshold where there is no carrier inversion layer, so the transistor channel has a high associated resistance. The main problem of the MOS transistor used as a resistor in this region is that the current Id has an exponential behavior with respect to the drain, source and gate terminals that generates distortion in the processed signal. To solve this problem, circuits have been proposed in the literature that maintain the resistance independent of the voltajes applied to the terminals of the PR, but all of them introduce distortion that increases gradually as the voltage applied to its terminals increases. In this thesis we study the conditions under which it is possible to reduce the distortion of the Pseudo-resistors so that their behavior resembles that of an ideal resistance. From these conditions, 3 Pseudo-resistor topologies are proposed. Using the proposed resistors, two amplifiers were designed for biomedical applications with band pass response, which were sized using the gm=Id technique. The results show that the circuits obtained have better characteristics than others reported in the literature. Finally, two notch filters tuned at 60Hz were designed, one using a PR from the literature and another with one from the proposed PR. The simulations show that both the linear excursion and the quality factor improve while maintaining a distortion below 1 %. All simulations were performed in HSPICE and 0.5μm in On-semi technology. |
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