Contribución al modelado y diseño de moduladores sigma-delta en tiempo continuo de baja relación de sobremuestreo y bajo consumo de potencia

Continuous-Time Sigma-Delta modulators are often employed as analog-to-digital converters. These modulators are an attractive approach to implement high-speed converters in VLSI systems because they have low sensitivity to circuit imperfections compared to other solutions. This work is a contribution to the analysis, modelling and design of high-speed Continuous-Time Sigma-Delta modulators. The resolution and the stability of these modulators are limited by two main factors, excess-loop delay and sampling uncertainty. Both factors, among others, have been carefully analysed and modelled. A new design methodology is also proposed. It can be used to get an optimum high-speed Continuous-Time Sigma-Delta modulator in terms of dynamic range, stability and sensitivity to sampling uncertainty. Based on the proposed design methodology, a software tool that covers the main steps has been developed. The methodology has been proved by using the tool in designing a 30 Megabits-per-second Continuous-Time Sigma-Delta modulator with 11-bits of dynamic range. The modulator has been integrated in a 0.13-µm CMOS technology and it has a measured peak SNR of 62.5dB

Time-encoded audio MEMS sensors optimized for edge computing

Proceedings of XXXVII Conference on desing of circuits and integrated systems (DCIS 2022), 16-18 November 2022, Pamplona, Spain.This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 956601

Low Power Phase-Encoded MAC Accelerator for Smart Sensors with VCO-based ADCs

Proceeding of: 2020 IEEE 63rd International Midwest Symposium on Circuits and Systems (MWSCAS): August 9-12, 2020, Springfield, MA, USA: on-line proceedings.A new phase-encoded MAC cell is proposed for low power smart sensing applications. If digitization of the raw data is made through voltage-controlled-oscillators based analog-to-digital converters (VCO-based ADCs), we may take the unsampled frequency-encoded output signal and connect it to the first layer of a neural network. Then that layer could be implemented with phase-encoded MAC accelerators, leading to an energy-efficient solution. The MAC cell does not only make the accumulation/subtraction and multiplication operation, but also the non-linear function which supposes a great advantage with respect to other equivalent cells. A circuit example is proposed in a 65-nm CMOS process and transient simulations prove the feasibility of the approach.Publicad

A Time-Encoded Capacitance-to-Digital Converter Based on a Switched-Capacitor Feedback

An innovative method to perform capacitance-to-digital conversion without requiring sensor biasing circuitry is proposed. This letter is intended for the readout of MEMS capacitive microphones used in human-to-machine interface applications, where the main constraints are low power consumption and small chip area. The time-encoded sigma-delta ADC described here employs a switched-capacitor-based feedback to linearize the voltage-controlled oscillator and to couple the capacitive sensor to the readout. A prototype was fabricated to test the concept with a CMOS 130-nm process. The achieved relative capacitance resolution is 14.7 b with a rest capacitance value of 2.575pF and a total power consumption of 343μW . Linearity measurements ( SNDRpeak=51.5 dB in the bandwidth from 300Hz to 6.8kHz ) are limited by the test fixture due to the nonlinearity of the varactor introduced in lieu of a testing input sensor.The project funded from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 956601, involves the collaboration between Universidad Carlos III de Madrid and Infineon Technologies AG Austria

Ring-oscillator with multiple transconductors for linear analog-to-digital conversion

This paper proposes a new circuit-based approach to mitigate nonlinearity in open-loop ring-oscillator-based analog-to-digital converters (ADCs). The approach consists of driving a current-controlled oscillator (CCO) with several transconductors connected in parallel with different bias conditions. The current injected into the oscillator can then be properly sized to linearize the oscillator, performing the inverse current-to-frequency function. To evaluate the approach, a circuit example has been designed in a 65-nm CMOS process, leading to a more than 3-ENOB enhancement in simulation for a high-swing differential input voltage signal of 800-mVpp, with considerable less complex design and lower power and expected area in comparison to state-of-the-art circuit based solutions. The architecture has also been checked against PVT and mismatch variations, proving to be highly robust, requiring only very simple calibration techniques. The solution is especially suitable for high-bandwidth (tens of MHz) medium-resolution applications (10–12 ENOBs), such as 5G or Internet-of-Things (IoT) devices.This research was funded by Project TEC2017-82653-R, Spain

Jardins per a la salut

Facultat de Farmàcia, Universitat de Barcelona. Ensenyament: Grau de Farmàcia. Assignatura: Botànica farmacèutica. Curs: 2014-2015. Coordinadors: Joan Simon, Cèsar Blanché i Maria Bosch.Els materials que aquí es presenten són el recull de les fitxes botàniques de 128 espècies presents en el Jardí Ferran Soldevila de l’Edifici Històric de la UB. Els treballs han estat realitzats manera individual per part dels estudiants dels grups M-3 i T-1 de l’assignatura Botànica Farmacèutica durant els mesos de febrer a maig del curs 2014-15 com a resultat final del Projecte d’Innovació Docent «Jardins per a la salut: aprenentatge servei a Botànica farmacèutica» (codi 2014PID-UB/054). Tots els treballs s’han dut a terme a través de la plataforma de GoogleDocs i han estat tutoritzats pels professors de l’assignatura. L’objectiu principal de l’activitat ha estat fomentar l’aprenentatge autònom i col·laboratiu en Botànica farmacèutica. També s’ha pretès motivar els estudiants a través del retorn de part del seu esforç a la societat a través d’una experiència d’Aprenentatge-Servei, deixant disponible finalment el treball dels estudiants per a poder ser consultable a través d’una Web pública amb la possibilitat de poder-ho fer in-situ en el propi jardí mitjançant codis QR amb un smartphone

An Unbiased MEMS Capacitance-Controlled Oscillator as a Microphone for HMI Applications

Proceeding of AUSTROCHIP 2022: 30th Austrian Workshop on Microelectronics, October 11th, Villach, Austria.MEMS microphones are usually DC biased with a voltage exceeding 10V and a large resistance, requiring a charge pump and a high-ohmic link between the ASIC and the MEMS. This DC biasing is needed to obtain enough sensitivity for medium to high quality microphones. This manuscript inves-tigates capacitance-controlled oscillators which allow to directly connect the MEMS sensor to the oscillator; this solution is prone to scaling. A new type of configuration (referred to as Cross-Connected Sensor) is presented and discussed. Its main advantage is the increase in the sensitivity and, when integrated in an ADC architecture, in the achievable SNR. The proposed solution is intended for Human-Machine Interface applications given their moderate SNR requirements.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 956601.Publicad