Home » Departamento de Electrónica » Defensa Virtual Tesis Doctorado : “On the design of ultra low voltage CMOS oscillators”

Defensa Virtual Tesis Doctorado : “On the design of ultra low voltage CMOS oscillators”

Martes 28 de abril 09:30hs

Tenemos el agrado de invitarlos a la defensa virtual de la tesis de doctorado de  Mariana Siniscalchi : “On the design of ultra low voltage CMOS oscillators”

Tutor : Carlos Galup-Montoro (Universidade Federal de Santa Catarina, Brasil) y Fernando Silveira (IIE)

Tribunal : Andreas Andreou (Johns Hopkins University, Estados Unidos), Sylvain Bourdel (Université Grenoble Alpes, Francia) y Conrado Rossi (IIE)

Podrán asistir como público a la defensa, a través del mismo canal que usará la tesista y el tribunal, a través de Zoom

En esta plataforma no es necesario que se registren, si puede que les pidan para ejecutar algo a partir de vuestro navegador

Link para unirse a la reunión Zoom de la defensa : (solicitar en jribeiro@fing.edu.uy)

Les pedimos algunas consideraciones sencillas : Identifíquense al ingresar con vuestro nombre y apellido real (no con un alias), mantengan vuestro micrófono silenciado (excepto si quieren hacer una pregunta cuando se de esta posibilidad al público o para vitorear al candidato en los momentos en que el público habitualmente lo hace), y mantengan vuestro video apagado

Al finalizar las preguntas del tribunal, cuando el público se retira de la sala en una defensa presencial, deberán desconectarse de la reunión

Tanto la candidata como el público para “retornar” a escuchar el fallo del tribunal deberán acceder a la reunión: (solicitar en jribeiro@fing.edu.uy)

Esta segunda reunión cuenta con una “sala de espera”, es decir que cuando pidan para entrar, quedarán en espera hasta que los admitamos

Plan B :

En caso de que esta plataforma falle en algún punto, pasaremos a usar Webex con las siguientes enlaces de reunión : (solicitar en jribeiro@fing.edu.uy)

Saludos,

Fernando Silveira

Resumen :

Wireless sensor nodes require very tight power budgets to operate from either a small battery or some energy harvesting mechanism, or both. In many cases,thermal or electrochemical harvesting devices provide very low voltages of the order of 100 mV or even lower. Time-keeping functionality is required in IoT systems and the time-keeping module must be on at all times. Crystal oscillators have proven to be useful for low power time-keeping applications, and in this context supply voltage lowering is a convenient strategy. Therefore, 32 kHz crystal oscillators operating with only 60 mV supply are presented. Two implementations based on a Schmitt trigger circuit for two different crystals were designed and experimentally characterized. These crystal oscillators are based on the application of a Schmitt trigger as an amplifier. Guidelines for designing this block to be the amplifier of a crystal oscillator are provided. Furthermore, a dynamic model of the Schmitt trigger is proposed and the model results are compared against simulations. The amplifiers were experimentally characterized, providing a gain of 2.48 V/V with a 60 mV power supply. As it was intended in the design stage, for voltages above 100 mV hysteresis appears and the Schmitt trigger starts operating as a comparator. The Schmitt triggers to operate as amplifiers of the crystal oscillators are designed in a 130 nm CMOS process, requiring an area of 45 μm x 74 μm and 78 μm x 83 μm, respectively. The power consumptions of the crystal oscillators are 2.26 nW and 15 nW and the temperature stabilities attained are 62 ppm (25-62°C) and 50 ppm (5-62°C), respectively. The dependence on the supply voltage of the current consumption, fractional frequency, start-up time and oscillation amplitude were measured. The Allan deviation is 30 ppb for both oscillators. On the other hand, an LC voltage controlled oscillator (VCO) is designed in 28 nm FD-SOI for RF applications. The possibility of modeling the transistors in  the 28 nm FD-SOI technology by means of the all inversion region long channel bulk transistor model used for the Schmitt trigger circuits, is studied. A crosscoupled nMOS architecture is used to build the VCO. The theoretical limit for the minimum supply voltage that enables oscillation is studied. The transistors were optimally sized to aim the minimum power consumption through a low-voltage approach and the performance of the VCO was obtained through simulations.