3,858 research outputs found

    Undergraduate Catalog of Studies, 2023-2024

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    Undergraduate Catalog of Studies, 2023-2024

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    A Wideband Contactless Electrical Impedance Tomography System

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    This work focuses on the development of a wideband contactless electrical impedance tomography (EIT) system. The system is developed from the aspects of the multifrequency capacitively coupled electrical impedance tomography (CCEIT) hardware, the impedance calculation model and the system evaluation. The hardware includes a 12-electrode CCEIT sensor, 6 sensing modules, a data acquisition module, and a personal computer (PC). The impedance calculation model is established by combining the mechanism modeling of the integrated circuits (ICs) and the empirical modeling of the measurement data with the least squares (LS) method. Experiments were carried out to evaluate the developed system, including the signal-to-noise ratio (SNR), the impedance measurement accuracy and the imaging performance. Experimental results show that the system achieves an SNR above 65.00 dB for the frequencies up to 20 MHz. Impedance measurement results indicate that the system has good impedance measurement accuracy at frequencies below 10 MHz and acceptable impedance measurement accuracy at 10 MHz - 20 MHz. It has particularly good performance at several specific frequencies, which can also serve as a high-performance single-frequency contactless EIT device. Imaging results show that the spectroscopic images reconstructed by the developed system are consistent with the actual distributions. Few types of research on contactless multifrequency EIT systems have been reported. So, this work is of great significance for further development and practical application of the newly emerged contactless EIT technique

    SiPM detector timing response study for the electron-ion collider

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    The Electron-Ion Collider (EIC) will be a new high luminosity large-scale and high polarization collider designed to investigate the QCD dynamics in the nucleons with unprecedented precision. It is planned to be built at the Brookhaven National Lab in the US. Through a dRICH prototype, the performance of Silicon PhotoMultipliers (SiPM), the baseline photo-sensor candidate for the dRICH was tested. The employed SiPM readout electronics chip, ALCOR, provides the time-of-hit measurement through the rollover, coarse and fine time contributions. In this dissertation, a study on the refinement of the Time Resolution of the Reference Timing system (owing to the fine time correction) is presented. The corrections applied in order to improve the value of the system Time Resolution is based on parameters obtained from the measured fine time component of the registered time coincidence signals. The performance of the calibration procedure described, several checks were performed on dedicated channels. The results show that it represents an accurate approximation for the correction of 90% of the analysed data. The performance of the studied SiPMs displayed satisfying results in both applications - the Imaging SiPMs were successful in registering the Cherenkov light signal and the Timing SiPMs provided a Reference Time value which allowed to correctly track the signal time-of-hits. The Reference Timing system was calibrated to provide a measured Time Resolution of 135 ± 2 ps. A preliminary study of the Imaging sensor Time Resolution, which for was calculated to be for a single photoelectron within approximately 500 ps, indicates that the value of the Timing system Time Resolution is adequate for the framework. Note that although these preliminary Time Resolution illustrate satisfactory results, they do not include corrections for effects such as time walk, time over threshold or low sensor bias voltage working conditions, which would presumably further improve the results

    Investigation into Photon Emissions as a Side-Channel Leakage in Two Microcontrollers: A Focus on SRAM Blocks

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    Microcontrollers are extensively utilized across a diverse range of applications. However, with the escalating usage of these devices, the risk to their security and the valuable data they process correspondingly intensifies. These devices could potentially be susceptible to various security threats, with side channel leakage standing out as a notable concern. Among the numerous types of side-channel leakages, photon emissions from active devices emerge as a potentially significant concern. These emissions, a characteristic of all semiconductor devices including microcontrollers, occur during their operation. Depending on the operating point and the internal state of the chip, these emissions can reflect the device’s internal operations. Therefore, a malicious individual could potentially exploit these emissions to gain insights into the computations being performed within the device. This dissertation delves into the investigation of photon emissions from the SRAM blocks of two distinct microcontrollers, utilizing a cost-effective setup. The aim is to extract information from these emissions, analyzing them as potential side-channel leakage points. In the first segment of the study, a PIC microcontroller variant is investigated. The quiescent photon emissions from the SRAM are examined. A correlation attack was successfully executed on these emissions, which led to the recovery of the AES encryption key. Furthermore, differential analysis was used to examine the location of SRAM bits. The combination of this information with the application of an image processing method, namely the Structural Similarity Index (SSIM), assisted in revealing the content of SRAM cells from photon emission images. The second segment of this study, for the first time, emphasizes on a RISC-V chip, examining the photon emissions of the SRAM during continuous reading. Probing the photon emissions from the row and column detectors led to the identification of a target word location, which is capable of revealing the AES key. Also, the content of target row was retrieved through the photon emissions originating from the drivers and the SRAM cells themselves. Additionally, the SSIM technique was utilized to determine the address of a targeted word in RISC-V photon emissions which cannot be analyzed through visual inspection. The insights gained from this research contribute to a deeper understanding of side-channel leakage via photon emissions and demonstrate its potential potency in extracting critical information from digital devices. Moreover, this information significantly contributes to the development of innovative security measures, an aspect becoming increasingly crucial in our progressively digitized world

    Undergraduate Catalog of Studies, 2022-2023

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    RF Wireless Power and Data Transfer : Experiment-driven Analysis and Waveform Design

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    The brisk deployment of the fifth generation (5G) mobile technology across the globe has accelerated the adoption of Internet of Things (IoT) networks. While 5G provides the necessary bandwidth and latency to connect the trillions of IoT sensors to the internet, the challenge of powering such a multitude of sensors with a replenishable energy source remains. Far-field radio frequency (RF) wireless power transfer (WPT) is a promising technology to address this issue. Conventionally, the RF WPT concepts have been deemed inadequate to deliver wireless power due to the undeniably huge over-the-air propagation losses. Nonetheless, the radical decline in the energy requirement of simple sensing and computing devices over the last few decades has rekindled the interest in RF WPT as a feasible solution for wireless power delivery to IoT sensors. The primary goal in any RF WPT system is to maximize the harvested direct current (DC) power from the minuscule incident RF power. As a result, optimizing the receiver power efficiency is pivotal for an RF WPT system. On similar lines, it is essential to minimize the power losses at the transmitter in order to achieve a sustainable and economically viable RF WPT system. In this regard, this thesis explores the system-level study of an RF WPT system using a digital radio transmitter for applications where alternative analog transmit circuits are impractical. A prototype test-bed comprising low-cost software-defined radio (SDR) transmitter and an off-the-shelf RF energy-harvesting (EH) receiver is developed to experimentally analyze the impact of clipping and nonlinear amplification at the digital radio transmitter on digital baseband waveform. The use of an SDR allows leveraging the test-bed for the research on RF simultaneous wireless information and power transfer (SWIPT); the true potential of this technology can be realized by utilizing the RF spectrum to transport data and power together. The experimental results indicate that a digital radio severely distorts high peak-to-average power ratio (PAPR) signals, thereby reducing their average output power and rendering them futile for RF WPT. On similar lines, another test-bed is developed to assess the impact of different waveforms, input impedance mismatch, incident RF power, and load on the receiver power efficiency of an RF WPT system. The experimental results provide the foundation and notion to develop a novel mathematical model for an RF EH receiver. The parametric model relates the harvested DC power to the power distribution of the envelope signal of the incident waveform, which is characterized by the amplitude, phase and frequency of the baseband waveform. The novel receiver model is independent of the receiver circuit’s matching network, rectifier configuration, number of diodes, load as well as input frequency. The efficacy of the model in accurately predicting the output DC power for any given power-level distribution is verified experimentally. Since the novel receiver model associates the output DC power to the parameters of the incident waveform, it is further leveraged to design optimal transmit wave-forms for RF WPT and SWIPT. The optimization problem reveals that a constant envelope signal with varying duty cycle is optimal for maximizing the harvested DC power. Consequently, a pulsed RF waveform is optimal for RF WPT, whereas a continuous phase modulated pulsed RF signal is suitable for RF SWIPT. The superior WPT performance of pulsed RF waveforms over multisine signals is demonstrated experimentally. Similarly, the pulsed phase-shift keying (PSK) signals exhibit superior receiver power efficiency than other communication signals. Nonetheless, varying the duty-cycle of pulsed PSK waveform leads to an efficiency—throughput trade-off in RF SWIPT. Finally, the SDR test-bed is used to evaluate the overall end-to-end power efficiency of different digital baseband waveforms through wireless measurements. The results indicate a 4-PSK modulated signal to be suitable for RF WPT considering the overall power efficiency of the system. The corresponding transmitter, channel and receiver power efficiencies are evaluated as well. The results demonstrate the transmitter power efficiency to be lower than the receiver power efficiency

    Parasitic extraction of a power management integrated circuit PCB

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    Abstract. In this master’s thesis parasitic extraction of a power management integrated circuit was established and evaluated using Ansys Q3D. From PCB the S21 parameter was extracted between two nodes from output and input to efficiently show the parasitic properties of the PCB. Extraction was done over frequencies from 100 kHz to 100 MHz. This was done using multiple different settings for the extraction to find out the optimal settings in terms of accuracy and time to solution. An evaluation module PCB was designed for the power management integrated circuit using Altium. In this design the best practices for PCB layout design were utilized to get the performance as good as possible. Some of the PCB design choices were evaluated with Ansys Q3D to make an informed decision of the better design choice. A measurement setup was established and validated by using a known component to ensure the setup is working as expected. The PCB was measured without components except the ones needed for the experiment. Measurements were taken with S21 shunt-through method with spectrum analyser with built-in network option, external vector signal generator and external pre-amplifier to get more dynamic range. The output and input were evaluated with and without a capacitor to get a broader understanding of the modelling accuracy. A case with two capacitors was tested. These models were compared with a measurement result to evaluate the accuracy of the tools and methods. It was noticed that with simple geometries the different extraction options do not significantly affect the extraction accuracy. At the same time, the time to solution varies greatly which leads to the use of the simpler extraction settings to save time. When comparing the simulation with measurement the best average error was 3.3 % and the worst 34.3 %. The simulations matched the measurements best when a capacitor was placed and worst with open termination with no components. The model accuracies obtained in this thesis reflect what has been seen in previous studies in terms of frequency range and deviation from measured results.Parasiittisten ominaisuuksien ekstraktointi tehonhallinta piirilevyltä. Tiivistelmä. Tässä diplomityössä parasiittisten ominaisuuksien ekstraktointityövaihe luotiin, sekä sen suorituskyky arvioitiin käyttäen Ansys Q3D ohjelmaa. Piirilevyltä ekstraktoitiin S21 parametri kahden solmun väliltä tulo- ja lähtöpuolelta käyttäen 100 kHz–100 MHz taajuusaluetta. Tällä tavoin saatiin tehokkaasti esitettyä piirilevyn parasiittisten ominaisuuksien muodostama impedanssi. Tämä tehtiin käyttäen useita eri asetuksia, joita on saatavilla ohjelmistossa. Nämä asetukset vaikuttavat eri tavoilla ekstraktoinnin tarkkuuteen. Näitä tuloksia vertailemalla löydettiin tarkkuuden ja simulointiajan suhteen optimaaliset asetukset, joilla tehdä ekstraktointi. Työtä varten suunniteltiin piirilevy tehonhallinta integroidulle piirille käyttäen Altium ohjelmaa. Tässä suunnittelussa käytettiin hyviä käytänteitä, jotta piirilevyn suorituskyvystä saataisiin mahdollisimman hyvä. Jotkin suunnitteluvalinnoista perustuvat Q3D:llä saatuihin tuloksiin, jotta voitiin valita useista vaihtoehdoista paras. Mittauksia varten suunniteltiin ja toteutettiin mittausjärjestelmä, jonka toiminta varmennettiin mittaamalla tunnetun komponentin impedanssi ja vertaamalla sitä valmistajan antamaan dataan. Valmistetulta piirilevyltä mitattiin käyttäen vain niitä komponentteja, jotka olivat merkittäviä tutkimukselle. Mittaukset tehtiin käyttäen S21 shunt-through menetelmää käyttämällä spektrianalysaattoria, jossa on sisäänrakennettu verkkoanalysointioptio. Tämän kanssa käytettiin ulkoista vektorisignaaligeneraattoria ja ulkoista esivahvistinta, jotta saataisiin enemmän dynaamista aluetta. Vertailuun valittiin piirin ulos- ja sisääntuloverkot kondensaattorilla ja ilman, jotta saataisiin laajempi käsitys mallinnuksen tarkkuudesta. Myös kahden kondensaattorin tapaus käsiteltiin. Näitä mallinnuksella saatuja tuloksia verrattiin mittaamalla saatuihin tuloksiin. Työssä huomattiin, että tässä sovelluksessa, jossa on yksinkertaisia geometrioita, eri ekstraktointi vaihtoehdot eivät vaikuttaneet tarkkuuteen huomattavasti. Ekstraktointiin kulunut aika vaihteli huomattavasti joidenkin vaihtoehtojen välillä, jonka takia valittiin yksinkertaisempi mallinnustapa, jotta säästettäisiin aikaa. Verrattaessa simuloituja ja mitattuja tuloksia, huomattiin että paras keskiarvoinen virhe oli 3,3 % ja huonoin 34,3 %. Simuloinnit vastasivat mittauksia parhaiten, kun tarkasteltiin tapauksia, joissa oli käytössä yksi kondensaattori ja huonoin, kun käytettiin avointa terminointia. Tässä työssä saadut tulokset vastaavat hyvin aikaisemmissa tutkimuksissa saatuja tuloksia sekä taajuusalueen puolesta, että eron mittauksen ja simuloinnin välillä

    Towards a muon collider

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    A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work

    Accurate quantum transport modelling and epitaxial structure design of high-speed and high-power In0.53Ga0.47As/AlAs double-barrier resonant tunnelling diodes for 300-GHz oscillator sources

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    Terahertz (THz) wave technology is envisioned as an appealing and conceivable solution in the context of several potential high-impact applications, including sixth generation (6G) and beyond consumer-oriented ultra-broadband multi-gigabit wireless data-links, as well as highresolution imaging, radar, and spectroscopy apparatuses employable in biomedicine, industrial processes, security/defence, and material science. Despite the technological challenges posed by the THz gap, recent scientific advancements suggest the practical viability of THz systems. However, the development of transmitters (Tx) and receivers (Rx) based on compact semiconductor devices operating at THz frequencies is urgently demanded to meet the performance requirements calling from emerging THz applications. Although several are the promising candidates, including high-speed III-V transistors and photo-diodes, resonant tunnelling diode (RTD) technology offers a compact and high performance option in many practical scenarios. However, the main weakness of the technology is currently represented by the low output power capability of RTD THz Tx, which is mainly caused by the underdeveloped and non-optimal device, as well as circuit, design implementation approaches. Indeed, indium phosphide (InP) RTD devices can nowadays deliver only up to around 1 mW of radio-frequency (RF) power at around 300 GHz. In the context of THz wireless data-links, this severely impacts the Tx performance, limiting communication distance and data transfer capabilities which, at the current time, are of the order of few tens of gigabit per second below around 1 m. However, recent research studies suggest that several milliwatt of output power are required to achieve bit-rate capabilities of several tens of gigabits per second and beyond, and to reach several metres of communication distance in common operating conditions. Currently, the shortterm target is set to 5−10 mW of output power at around 300 GHz carrier waves, which would allow bit-rates in excess of 100 Gb/s, as well as wireless communications well above 5 m distance, in first-stage short-range scenarios. In order to reach it, maximisation of the RTD highfrequency RF power capability is of utmost importance. Despite that, reliable epitaxial structure design approaches, as well as accurate physical-based numerical simulation tools, aimed at RF power maximisation in the 300 GHz-band are lacking at the current time. This work aims at proposing practical solutions to address the aforementioned issues. First, a physical-based simulation methodology was developed to accurately and reliably simulate the static current-voltage (IV ) characteristic of indium gallium arsenide/aluminium arsenide (In-GaAs/AlAs) double-barrier RTD devices. The approach relies on the non-equilibrium Green’s function (NEGF) formalism implemented in Silvaco Atlas technology computer-aided design (TCAD) simulation package, requires low computational budget, and allows to correctly model In0.53Ga0.47As/AlAs RTD devices, which are pseudomorphically-grown on lattice-matched to InP substrates, and are commonly employed in oscillators working at around 300 GHz. By selecting the appropriate physical models, and by retrieving the correct materials parameters, together with a suitable discretisation of the associated heterostructure spatial domain through finite-elements, it is shown, by comparing simulation data with experimental results, that the developed numerical approach can reliably compute several quantities of interest that characterise the DC IV curve negative differential resistance (NDR) region, including peak current, peak voltage, and voltage swing, all of which are key parameters in RTD oscillator design. The demonstrated simulation approach was then used to study the impact of epitaxial structure design parameters, including those characterising the double-barrier quantum well, as well as emitter and collector regions, on the electrical properties of the RTD device. In particular, a comprehensive simulation analysis was conducted, and the retrieved output trends discussed based on the heterostructure band diagram, transmission coefficient energy spectrum, charge distribution, and DC current-density voltage (JV) curve. General design guidelines aimed at enhancing the RTD device maximum RF power gain capability are then deduced and discussed. To validate the proposed epitaxial design approach, an In0.53Ga0.47As/AlAs double-barrier RTD epitaxial structure providing several milliwatt of RF power was designed by employing the developed simulation methodology, and experimentally-investigated through the microfabrication of RTD devices and subsequent high-frequency characterisation up to 110 GHz. The analysis, which included fabrication optimisation, reveals an expected RF power performance of up to around 5 mW and 10 mW at 300 GHz for 25 μm2 and 49 μm2-large RTD devices, respectively, which is up to five times higher compared to the current state-of-the-art. Finally, in order to prove the practical employability of the proposed RTDs in oscillator circuits realised employing low-cost photo-lithography, both coplanar waveguide and microstrip inductive stubs are designed through a full three-dimensional electromagnetic simulation analysis. In summary, this work makes and important contribution to the rapidly evolving field of THz RTD technology, and demonstrates the practical feasibility of 300-GHz high-power RTD devices realisation, which will underpin the future development of Tx systems capable of the power levels required in the forthcoming THz applications
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