134 research outputs found
The development of liquid crystal lasers for application in fluorescence microscopy
Lasers can be found in many areas of optical medical imaging and their properties have enabled the rapid advancement of many imaging techniques and modalities. Their narrow linewidth, relative brightness and coherence are advantageous in obtaining high quality images of biological samples. This is particularly beneficial in fluorescence microscopy. However, commercial imaging systems depend on the combination of multiple independent laser sources or use tuneable sources, both of which are expensive and have large footprints. This thesis demonstrates the use of liquid crystal (LC) laser technology, a compact and portable alternative, as an exciting candidate to provide a tailorable light source for fluorescence microscopy.
Firstly, to improve the laser performance parameters such that high power and high specification lasers could be realised; device fabrication improvements were presented. Studies exploring the effect of alignment layer rubbing depth and the device cell gap spacing on laser performance were conducted. The results were the first of their kind and produced advances in fabrication that were critical to repeatedly realising stable, single-mode LC laser outputs with sufficient power to conduct microscopy. These investigations also aided with the realisation of laser diode pumping of LC lasers. Secondly, the identification of optimum dye concentrations for single and multi-dye systems were used to optimise the LC laser mixtures for optimal performance. These investigations resulted in novel results relating to the gain media in LC laser systems. Collectively, these advancements yielded lasers of extremely low threshold, comparable to the lowest reported thresholds in the literature.
A portable LC laser system was integrated into a microscope and used to perform fluorescence microscopy. Successful two-colour imaging and multi-wavelength switching ability of LC lasers were exhibited for the first time. The wavelength selectivity of LC lasers was shown to allow lower incident average powers to be used for comparable image quality. Lastly, wavelength selectivity enabled the LC laser fluorescence microscope to achieve high enough sensitivity to conduct quantitative fluorescence measurements. The development of LC lasers and their suitability to fluorescence microscopy demonstrated in this thesis is hoped to push towards the realisation of commercialisation and application for the technology
D-Band downconversion mixer design in CMOS-SOI
Abstract. The current surge in research interest around the sub-THz frequency region comes as a no surprise. The potential for greater data rates and available bandwidths are just a couple reasons why research around these frequencies should be prioritized. Many viable receiver structures have been presented for these frequency regions, but they all have one thing in common: They all include a downconversion mixer. The mixer is a crucial piece in the receiver structure, converting the higher frequency radio frequency (RF) signal to a much lower intermediate frequency (IF) signal using multiplication with a local oscillator (LO) signal. The resulting waveform is much easier to handle for signal processing that comes after. The downconversion should be able to provide a fair amount of gain to the converted signal on a wide range of input signals, measured with the 1dB compression point. The noise figure is also a major consideration for RF-devices, but in the case of the mixer, its importance is not as prevalent as it is for the LNA that precedes it, since the noise of the mixer is attenuated by the gain of the previous stages.
This master’s thesis work introduces the basic theory around downconversion mixers, followed by the design of a mixer from schematic level circuit design all the way to the physical layout. The physical design is done using 22nm FDSOI technology, provided by GlobalFoundries. The design is made for a direct conversion receiver using Gilbert cell topology, meaning image rejection is reasonable and depends only on the received signal itself, and good noise and feedthrough performance should be expected in simulations. The mixer is to downconvert a 151 GHz signal down to 0–1 GHz, using an LO signal between 150–151 GHz. Two iterations of the mixer are shown in the end results, the first one being based on the schematic design, and the second one with adjustments made for better performance. While driving a high impedance 500 Ohm load, the second iteration was able to reach a conversion gain of -10.0 dB with a 1dB compression point of 6.4 dBm while dissipating 4.7 mW of power. DSB noise figure was simulated to be 17.3 dB and the LO leakage to the IF output at -27.7 dBm.Alaspäin taajuusmuuntavan sekoittimen suunnittelu D-kaistalle käyttäen CMOS-SOI teknologiaa. Tiivistelmä. Nykyinen tutkimuksen keskittyminen millimetriaalto ja THz taajuusalueille ei tule kenellekään yllätyksenä. Suurempien datanopeuksien ja vapaiden taajuuskaistojen potentiaali ovat vain joitain monista hyvistä käytännön syistä, miksi tutkimusta näiden taajuuksien ympärillä priorisoidaan. Monia käytännöllisiä vastaanotinrakenteita on esitetty näille taajuusalueille ja niillä on kaikilla yksi yhteinen tekijä: tajuusmuunnin alemmille taajuuksille. Taajuusmuunnin eli sekoitin on olennainen osa vastaanotinrakenteita, muuntaen korkeamman radiotaajuuden (RF) matalammalle välitaajuudelle (IF) käyttäen taajuuksien sekoittamista paikallisoskillaattorilla (LO). Mikserin ulostulosignaali on signaalinprosessoinnin näkökulmasta paljon käytännöllisempi. Alaspäin taajuusmuuntavan mikserin tulee pystyä vahvistamaan laajaa skaalaa erivahvuisia signaaleja, minkä ylärajaa mittaamme 1 dB kompressiopisteellä. Radiolaitteistossa kohinaluku tulee yleensä myös ottaa huomioon, mutta johtuen mikserin sijainnista vastaanotinketjussa, kohinaluku vaimenee suhteessa sitä edeltävien vahvistuksien verran, eikä siksi ole niin kriittinen.
Tämä diplomityö esittelee lukijalle ensiksi alaspäin muuntavan taajuussekoittimen perusteorian, toisena sen teoreettisen piirikaavion suunnittelun sekä sen simuloinnin tuloksia, ja viimeisenä fyysisen layoutin suunnittelun sekä sen simuloinnin tulokset. Fyysisen layoutin suunnittelu ja simulointi tehdään käyttäen GlobalFoundries 22nm FDSOI teknologiaa. Suunnittelu tehdään suoramuunnosvastaanottimelle käyttäen Gilbertin solu topologiaa, eliminoiden peilitaajuuksista aiheutuvat ongelmat, sekä vähentäen kohinan sekä ei-haluttujen signaalien läpivuotojen vaikutusta. Sekoittimen tulee muuntaa 151 GHz signaali n. 0–1 GHz kantataajuudelle käyttäen LO-signaalia taajuusvälillä 150–151 GHz. Lopullisissa tuloksissa vertaillaan kahta eri iteraatiota. Ensimmäisenä versiota, joka luotiin alun perin teoriapohjaisen piirisuunnittelun pohjalta, sekä toista versiota, missä useilla parannuksilla mikserin suorituskykyä saatiin parannettua. Korkeaimpedanssista 500 Ohmin kuormaa ajaessa mikseri ylsi -10.0 dB vahvistukseen, 1 dB kompressiopiste oli 6.4 dB kuluttaen 4.7 mW virtaa käytössä. Kohinaluvuksi simuloitiin 17.3 dB, sekä LO signaalin vuodosta IF lähtöön oli -27.7 dBm
Amplifiers in Biomedical Engineering: A Review from Application Perspectives
Continuous monitoring and treatment of various diseases with biomedical technologies and wearable electronics has become significantly important. The healthcare area is an important, evolving field that, among other things, requires electronic and micro-electromechanical technologies. Designed circuits and smart devices can lead to reduced hospitalization time and hospitals equipped with high-quality equipment. Some of these devices can also be implanted inside the body. Recently, various implanted electronic devices for monitoring and diagnosing diseases have been presented. These instruments require communication links through wireless technologies. In the transmitters of these devices, power amplifiers are the most important components and their performance plays important roles. This paper is devoted to collecting and providing a comprehensive review on the various designed implanted amplifiers for advanced biomedical applications. The reported amplifiers vary with respect to the class/type of amplifier, implemented CMOS technology, frequency band, output power, and the overall efficiency of the designs. The purpose of the authors is to provide a general view of the available solutions, and any researcher can obtain suitable circuit designs that can be selected for their problem by reading this survey
Reconfigurable Receiver Front-Ends for Advanced Telecommunication Technologies
The exponential growth of converging technologies, including augmented reality, autonomous vehicles, machine-to-machine and machine-to-human interactions, biomedical and environmental sensory systems, and artificial intelligence, is driving the need for robust infrastructural systems capable of handling vast data volumes between end users and service providers. This demand has prompted a significant evolution in wireless communication, with 5G and subsequent generations requiring exponentially improved spectral and energy efficiency compared to their predecessors. Achieving this entails intricate strategies such as advanced digital modulations, broader channel bandwidths, complex spectrum sharing, and carrier aggregation scenarios. A particularly challenging aspect arises in the form of non-contiguous aggregation of up to six carrier components across the frequency range 1 (FR1). This necessitates receiver front-ends to effectively reject out-of-band (OOB) interferences while maintaining high-performance in-band (IB) operation. Reconfigurability becomes pivotal in such dynamic environments, where frequency resource allocation, signal strength, and interference levels continuously change. Software-defined radios (SDRs) and cognitive radios (CRs) emerge as solutions, with direct RF-sampling receivers offering a suitable architecture in which the frequency translation is entirely performed in digital domain to avoid analog mixing issues. Moreover, direct RF- sampling receivers facilitate spectrum observation, which is crucial to identify free zones, and detect interferences. Acoustic and distributed filters offer impressive dynamic range and sharp roll off characteristics, but their bulkiness and lack of electronic adjustment capabilities limit their practicality. Active filters, on the other hand, present opportunities for integration in advanced CMOS technology, addressing size constraints and providing versatile programmability. However, concerns about power consumption, noise generation, and linearity in active filters require careful consideration.This thesis primarily focuses on the design and implementation of a low-voltage, low-power RFFE tailored for direct sampling receivers in 5G FR1 applications. The RFFE consists of a balun low-noise amplifier (LNA), a Q-enhanced filter, and a programmable gain amplifier (PGA). The balun-LNA employs noise cancellation, current reuse, and gm boosting for wideband gain and input impedance matching. Leveraging FD-SOI technology allows for programmable gain and linearity via body biasing. The LNA's operational state ranges between high-performance and high-tolerance modes, which are apt for sensitivityand blocking tests, respectively. The Q-enhanced filter adopts noise-cancelling, current-reuse, and programmable Gm-cells to realize a fourth-order response using two resonators. The fourth-order filter response is achieved by subtracting the individual response of these resonators. Compared to cascaded and magnetically coupled fourth-order filters, this technique maintains the large dynamic range of second-order resonators. Fabricated in 22-nm FD-SOI technology, the RFFE achieves 1%-40% fractional bandwidth (FBW) adjustability from 1.7 GHz to 6.4 GHz, 4.6 dB noise figure (NF) and an OOB third-order intermodulation intercept point (IIP3) of 22 dBm. Furthermore, concerning the implementation uncertainties and potential variations of temperature and supply voltage, design margins have been considered and a hybrid calibration scheme is introduced. A combination of on-chip and off-chip calibration based on noise response is employed to effectively adjust the quality factors, Gm-cells, and resonance frequencies, ensuring desired bandpass response. To optimize and accelerate the calibration process, a reinforcement learning (RL) agent is used.Anticipating future trends, the concept of the Q-enhanced filter extends to a multiple-mode filter for 6G upper mid-band applications. Covering the frequency range from 8 to 20 GHz, this RFFE can be configured as a fourth-order dual-band filter, two bandpass filters (BPFs) with an OOB notch, or a BPF with an IB notch. In cognitive radios, the filter’s transmission zeros can be positioned with respect to the carrier frequencies of interfering signals to yield over 50 dB blocker rejection
Systematic Approaches for Telemedicine and Data Coordination for COVID-19 in Baja California, Mexico
Conference proceedings info:
ICICT 2023: 2023 The 6th International Conference on Information and Computer Technologies
Raleigh, HI, United States, March 24-26, 2023
Pages 529-542We provide a model for systematic implementation of telemedicine within a large evaluation center for COVID-19 in the area of Baja California, Mexico. Our model is based on human-centric design factors and cross disciplinary collaborations for scalable data-driven enablement of smartphone, cellular, and video Teleconsul-tation technologies to link hospitals, clinics, and emergency medical services for point-of-care assessments of COVID testing, and for subsequent treatment and quar-antine decisions. A multidisciplinary team was rapidly created, in cooperation with different institutions, including: the Autonomous University of Baja California, the Ministry of Health, the Command, Communication and Computer Control Center
of the Ministry of the State of Baja California (C4), Colleges of Medicine, and the College of Psychologists. Our objective is to provide information to the public and to evaluate COVID-19 in real time and to track, regional, municipal, and state-wide data in real time that informs supply chains and resource allocation with the anticipation of a surge in COVID-19 cases. RESUMEN Proporcionamos un modelo para la implementación sistemática de la telemedicina dentro de un gran centro de evaluación de COVID-19 en el área de Baja California, México. Nuestro modelo se basa en factores de diseño centrados en el ser humano y colaboraciones interdisciplinarias para la habilitación escalable basada en datos de tecnologías de teleconsulta de teléfonos inteligentes, celulares y video para vincular hospitales, clínicas y servicios médicos de emergencia para evaluaciones de COVID en el punto de atención. pruebas, y para el tratamiento posterior y decisiones de cuarentena. Rápidamente se creó un equipo multidisciplinario, en cooperación con diferentes instituciones, entre ellas: la Universidad Autónoma de Baja California, la Secretaría de Salud, el Centro de Comando, Comunicaciones y Control Informático.
de la Secretaría del Estado de Baja California (C4), Facultades de Medicina y Colegio de Psicólogos. Nuestro objetivo es proporcionar información al público y evaluar COVID-19 en tiempo real y rastrear datos regionales, municipales y estatales en tiempo real que informan las cadenas de suministro y la asignación de recursos con la anticipación de un aumento de COVID-19. 19 casos.ICICT 2023: 2023 The 6th International Conference on Information and Computer Technologieshttps://doi.org/10.1007/978-981-99-3236-
CMOS Wide Tuning Gilbert Mixer with Controllable IF Bandwidth in Upcoming RF Front End for Multi-Band Multi-Standard Applications
The current global system for mobile communications, wireless local area, Bluetooth, and ultra-wideband demands a multi-band/multi-standard RF front end that can access all the available bandwidth specifications. Trade-offs occur between power consumption, noise figure, and linearity in CMOS Gilbert mixer wide tuning designs. Besides, it is preferable to have a constant IF bandwidth for different gain settings as the bandwidth varies with the load impedance when an RF receiver is tuned to a higher frequency. My dissertation consists of three parts. First, a tunable constant IF bandwidth Gilbert mixer is introduced for multi-band standard wireless applications such as 802.11 a/b/g WLAN and 802.16a WMAN, followed by a design synthesis approach to optimize the mixer to meet the design center frequency range, constant IF bandwidth, and power. A synthesized Gilbert mixer with effective prototype inductors, designed in 180 nm CMOS process, is presented in this dissertation with the tunability of 200 MHz IF, a constant IF bandwidth of 50 MHz, a conversion gain of 13.75 dB, a noise figure of 2.9dB, 1-dB compression point of -15.19 dBm, IIP3 of -5.8 dBm, and a power of 9 mW. Next, mixer inductor loss and equivalent electronic circuit analysis are presented to optimize the approach to offset center frequency and bandwidth inaccuracy due to the inductance loss between the actual and ideal prototype inductor. The proposed tunable Gilbert mixer simulations present a tunable IF of 177.8 MHz, an IF bandwidth of 87.57 MHz, a conversion gain of 7.4 dB, a noise figure of 3.14 dB, 1-dB compression point of -17.1 dBm, and IIP3 of -19.8 dBm. Last, a CMOS integrated wide frequency span CMOS low noise amplifier is integrated with the tunable Gilbert mixer to achieve a 27.68 dB conversion gain, a 3.47 dB low noise figure, -14.6 dBm 1-dB compression point, and -18.6 dBm IIP3
ECOS 2012
The 8-volume set contains the Proceedings of the 25th ECOS 2012 International Conference, Perugia, Italy, June 26th to June 29th, 2012. ECOS is an acronym for Efficiency, Cost, Optimization and Simulation (of energy conversion systems and processes), summarizing the topics covered in ECOS: Thermodynamics, Heat and Mass Transfer, Exergy and Second Law Analysis, Process Integration and Heat Exchanger Networks, Fluid Dynamics and Power Plant Components, Fuel Cells, Simulation of Energy Conversion Systems, Renewable Energies, Thermo-Economic Analysis and Optimisation, Combustion, Chemical Reactors, Carbon Capture and Sequestration, Building/Urban/Complex Energy Systems, Water Desalination and Use of Water Resources, Energy Systems- Environmental and Sustainability Issues, System Operation/ Control/Diagnosis and Prognosis, Industrial Ecology
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Surpassing Fundamental Limits through Time Varying Electromagnetics
Surpassing the fundamental limits that govern all electromagnetic structures, such as reciprocity and the delay-bandwidth-size limit, will have a transformative impact on all applications based on electromagnetic circuits and systems. For instance, violating principles of reciprocity enables non-reciprocal components such as isolators and circulators, which find application in full-duplex wireless radios, radar, biomedical imaging, and quantum computing systems. Overcoming the delay-bandwidth-size limit enables ultra-broadband yet extremely-compact devices whose size is not fundamentally related to the wavelength at the operating frequency. The focus of this dissertation is on using time-variance as a new toolbox to overcome these fundamental limits and re-imagine circuit and system design.
Traditional non-reciprocal components are realized using ferrite materials that loose their reciprocity under the application of external magnetic bias. However, the sheer volume, cost and weight of these magnet based non-reciprocal components coupled with their inability to be fabricated in conventional semiconductor processes, have limited their application to bulky and large-scale systems. Other approaches such as active-biased and non-linearity based non-reciprocity are compatible with semiconductor processes, however, they suffer from other poor linearity and noise performance. In this dissertation, using passive transistor switch as the modulating element, we have proposed the concept of spatio-temporal conductivity modulation and have demonstrated a gamut of non-reciprocal devices ranging from gyrators to isolators and circulators. Through novel circuit topologies, for the first time, we have demonstrated on-chip circulators with multi-watt input power handling, operation at high millimeter-wave frequencies, and tailor made circulators for emerging technologies such as simultaneous-transmit-and-receive MRI and quantum computing.
Delay-bandwidth-size trade-off is another fundamental electromagnetic limit, that constrains the delay imparted by a medium or a device within a fixed footprint to be inversely proportional to the signal bandwidth. It is this limit that governs the size of any microwave passive devices to be inversely proportional to its operating frequency. As a part of this dissertation, through intelligent clocking of switched capacitor networks we overcame the delay-bandwidth-size limit, thus resulting in infinitesimal, yet broadband microwave devices. Here we proposed a new paradigm in wave propagation where the properties such as the propagation delay and characteristic impedance does not depend on the constituent elements/materials of the medium, but rather heavily rely on the user-defined modulation scheme, thereby opening huge opportunities for realizing highly-reconfigurable passives. Leveraging these concepts, we demonstrated wide range of reciprocal an non-reciprocal devices including ultra-compact delay elements, highly-reconfigurable microwave passives, ultra-wideband circulators with infinitesimal form-factors and dispersion-free chip scale floquet topological insulators. Application of these devices have also been evaluated in real-world systems through our demonstrations of wideband, full-duplex receivers leveraging switched capacitors based true-time-delay interference cancelers and floquet topological insulator based antenna interfaces for full-duplex phased-arrays and ultra-wideband beamformers.
Furthermore, to cater the growing RF and microwave needs of future, large-scale quantum computing systems, we demonstrated a low-cryogenic, wideband circulator based on time modulation of superconducting devices. This superconducting circulator is expected to operate alongside the superconducting qubits, inside a dilution refrigerator at 10mK-100mK, thus enabling a tightly integrated quantum system. We also presented the design and implementation of a cryogenic-CMOS clock driver chip that will generate the clocks required by the superconducting circulator. Finally, we also demonstrated the design and implementation of a low-noise, low power consumption, 6GHz - 8GHz cryogenic downconversion receiver at 4K for cryogenic qubit readout
Low-Power Wake-Up Receivers
The Internet of Things (IoT) is leading the world to the Internet of Everything (IoE), where things, people, intelligent machines, data and processes will be connected together. The key to enter the era of the IoE lies in enormous sensor nodes being deployed in the massively expanding wireless sensor networks (WSNs). By the year of 2025, more than 42 billion IoT devices will be connected to the Internet. While the future IoE will bring priceless advantages for the life of mankind, one challenge limiting the nowadays IoT from further development is the ongoing power demand with the dramatically growing number of the wireless sensor nodes.
To address the power consumption issue, this dissertation is motivated to investigate low-power wake-up receivers (WuRXs) which will significantly enhance the sustainability of the WSNs and the environmental awareness of the IoT.
Two proof-of-concept low-power WuRXs with focuses on two different application scenarios have been proposed. The first WuRX, implemented in a cost-effective 180-nm CMOS semiconductor technology, operates at 401−406-MHz band. It is a good candidate for application scenarios, where both a high sensitivity and an ultra-low power consumption are in demand. Concrete use cases are, for instance, medical implantable applications or long-range communications in rural areas. This WuRX does not rely on a further assisting semiconductor technology, such as MEMS which is widely used in state-of-the-art WuRXs operating at similar frequencies. Thus, this WuRX is a promising solution to low-power low-cost IoT. The second WuRX, implemented in a 45-nm RFSOI CMOS technology, was researched for short-range communication applications, where high-density conventional IoT devices should be installed. By investigation of the WuRX for operation at higher frequency band from 5.5 GHz to 7.5 GHz, the nowadays ever more over-traffic issues that arise at low frequency bands such as 2.4 GHz can be substantially addressed.
A systematic, analytical research route has been carried out in realization of the proposed WuRXs. The thesis begins with a thorough study of state-of-the-art WuRX architectures. By examining pros and cons of these architectures, two novel architectures are proposed for the WuRXs in accordance with their specific use cases. Thereon, key WuRX parameters are systematically analyzed and optimized; the performance of relevant circuits is modeled and simulated extensively. The knowledge gained through these investigations builds up a solid theoretical basis for the ongoing WuRX designs. Thereafter, the two WuRXs have been analytically researched, developed and optimized to achieve their highest performance.
Proof-of-concept circuits for both the WuRXs have been fabricated and comprehensively characterized under laboratory conditions. Finally, measurement results have verified the feasibility of the design concept and the feasibility of both the WuRXs
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