268 research outputs found

    Radiation Tolerant Electronics, Volume II

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    Research on radiation tolerant electronics has increased rapidly over the last few years, resulting in many interesting approaches to model radiation effects and design radiation hardened integrated circuits and embedded systems. This research is strongly driven by the growing need for radiation hardened electronics for space applications, high-energy physics experiments such as those on the large hadron collider at CERN, and many terrestrial nuclear applications, including nuclear energy and safety management. With the progressive scaling of integrated circuit technologies and the growing complexity of electronic systems, their ionizing radiation susceptibility has raised many exciting challenges, which are expected to drive research in the coming decade.After the success of the first Special Issue on Radiation Tolerant Electronics, the current Special Issue features thirteen articles highlighting recent breakthroughs in radiation tolerant integrated circuit design, fault tolerance in FPGAs, radiation effects in semiconductor materials and advanced IC technologies and modelling of radiation effects

    Integrated optical sensors on the Si₃N₄-organic hybrid (SiNOH) platform

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    Ein wellenleiterbasierter Sensorchip wird demonstriert, der fĂŒr Point-of-Care-Anwendungen geeignet ist. Der Biosensor wird mit Hilfe eines mathematischen Modells entworfen, mit dem die SensitivitĂ€t der Wellenleiter untersucht wird. FĂŒr die Lichteinkopplung in die Wellenleiter wird erstmalig eine neue Klasse von integrierten Laserquellen fĂŒr sichtbare WellenlĂ€ngen untersucht. Die FunktionsfĂ€higkeit des wellenleiterbasierten Biosensorchips durch Detektionsexperimente erfolgreich nachgewiesen

    Contextual Beamforming: Exploiting Location and AI for Enhanced Wireless Telecommunication Performance

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    The pervasive nature of wireless telecommunication has made it the foundation for mainstream technologies like automation, smart vehicles, virtual reality, and unmanned aerial vehicles. As these technologies experience widespread adoption in our daily lives, ensuring the reliable performance of cellular networks in mobile scenarios has become a paramount challenge. Beamforming, an integral component of modern mobile networks, enables spatial selectivity and improves network quality. However, many beamforming techniques are iterative, introducing unwanted latency to the system. In recent times, there has been a growing interest in leveraging mobile users' location information to expedite beamforming processes. This paper explores the concept of contextual beamforming, discussing its advantages, disadvantages and implications. Notably, the study presents an impressive 53% improvement in signal-to-noise ratio (SNR) by implementing the adaptive beamforming (MRT) algorithm compared to scenarios without beamforming. It further elucidates how MRT contributes to contextual beamforming. The importance of localization in implementing contextual beamforming is also examined. Additionally, the paper delves into the use of artificial intelligence schemes, including machine learning and deep learning, in implementing contextual beamforming techniques that leverage user location information. Based on the comprehensive review, the results suggest that the combination of MRT and Zero forcing (ZF) techniques, alongside deep neural networks (DNN) employing Bayesian Optimization (BO), represents the most promising approach for contextual beamforming. Furthermore, the study discusses the future potential of programmable switches, such as Tofino, in enabling location-aware beamforming

    Development of a compact wireless SAW Pirani vacuum microsensor with extended range and sensitivity

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    Vakuumsensoren haben nach wie vor einen begrenzten Messbereich und erfordern eine aufwendige Verkabelung sowie eine komplexe Integration in Vakuumkammern. Ein kompakter Sensor, der in der Lage ist, den Erfassungsbereich zwischen Hochvakuum und AtmosphĂ€rendruck zu erweitern und dabei drahtlos zu arbeiten, ist Ă€ußerst wĂŒnschenswert. Der Schwerpunkt dieser Arbeit liegt auf dem Entwurf, der Simulation, der Herstellung und der experimentellen Validierung eines drahtlosen kompakten Vakuum-Mikrosensors mit erweiterter Reichweite und Empfindlichkeit. ZunĂ€chst wurde ein neuer Sensor unter Verwendung vorhandener und neu entwickelter Komponenten entworfen. Zweitens wurden die Sensorkomponenten simuliert, um ihre Parameter zu optimieren. Drittens wurde ein Prototyp unter Verwendung der verfĂŒgbaren Mikrobearbeitungs- und Halbleitertechnologien hergestellt und montiert. Viertens wurde der Prototyp unter Umgebungs- und Vakuumbedingungen charakterisiert, um seine Leistungen zu validieren. FĂŒr das Wandlerprinzip wurden zwei Techniken kombiniert, nĂ€mlich Pirani-Sensorik und akustische OberflĂ€chenwellen. Das Design der Sensorkomponenten bestand aus vier Einheiten: Sensoreinheit, Heizeinheit, Abfrageeinheit und GehĂ€use. Alle Einheiten wurden in einen kompakten WĂŒrfel eingebaut. Einige Komponenten wurden neu entwickelt, wĂ€hrend andere gekauft, modifiziert und dann miteinander verbunden wurden. Die Sensoreinheit besteht aus einem neuen Chip mit verbesserter Sensorleistung dank eines optimierten VerhĂ€ltnisses von OberflĂ€che zu Volumen. Die Heizeinheit wurde aus zwei induktiv gekoppelten Spulen und der zugehörigen Konditionierungselektronik zusammengesetzt. Die Abfrageeinheit wurde mit einer Mikro-Patch-Antenne hergestellt. Ein wĂŒrfelförmiges PolymergehĂ€use wurde entwickelt, um alle Komponenten in einer Vakuumkammer unterzubringen. Zweitens wurde die Simulation des Verhaltens der Sensorkomponenten behandelt. Die fĂŒr die Druckmessung verantwortliche WĂ€rmeĂŒbertragung des Sensorchips wurde vom Hochvakuum bis zum AtmosphĂ€rendruck untersucht, um seine Abmessungen zu optimieren. Die Verwendung eines hĂ€ngenden Lithium-Niobat-Chips mit Y-Z-Schnitt und einem TCF von 94 ppm/K fĂŒhrte zu einer verbesserten Leistung in einem Messbereich zwischen \num{d-4}~Pa und \num{e5}~Pa. Die elektronische Kopplung der Heizspulen wurde ebenfalls simuliert, um die LeistungsĂŒbertragung und den Kopplungsabstand zu optimieren. Der dritte Teil betrifft die Herstellungs- und Montageschritte des Prototyps unter Verwendung der verfĂŒgbaren Halbleitertechnologien und -ausrĂŒstung. Ein SAW Chip wurde mit einer 100~nm dicken Goldschicht an der Unterseite gesputtert, um den Heizwiderstand zu bilden, und mit Hilfe von Drahtbonding elektrisch mit dem Rest des Sensors verbunden. Es wurde eine Leiterplatte vorbereitet, die die Heiz- und Sensoreinheit enthĂ€lt. Ein kubisches GehĂ€usewurde aus PTFE hergestellt. Viertens wurden die Sensorkomponenten zunĂ€chst separat charakterisiert, um ihre Leistungen zu ĂŒberprĂŒfen, und dann zusammen unter Umgebungsbedingungen. SpĂ€ter wurde der Sensor im Vakuum integriert, und es wurde ein druckabhĂ€ngiges Verhalten des Sensorchips beobachtet. Die Relevanz eines drahtlosen Übertragungsverfahrens wurde den herkömmlichen drahtgebundenen Methoden gegenĂŒbergestellt. Die Ergebnisse der experimentellen Arbeiten außerhalb und innerhalb des Vakuums zeigten die Machbarkeit und Relevanz des neuen Konzepts

    Modelling, Analysis and Design of Optimised Electronic Circuits for Visible Light Communication Systems

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    This thesis explores new circuit design techniques and topologies to extend the bandwidth of visible light communication (VLC) transmitters and receivers, by ameliorating the bandwidth-limiting effects of commonly used optoelectronic devices. The thesis contains detailed literature review of transmitter and receiver designs, which inspired two directions of work. The first proposes new designs of optically lossless light emitting diode (LED) bandwidth extension technique that utilises a negative capacitance circuit to offset the diode’s bandwidth-limiting capacitance. The negative capacitance circuit was studied and verified through newly developed mathematical analysis, modelling and experimental demonstration. The bandwidth advantage of the proposed technique was demonstrated through measurements in conjunction with several colour LEDs, demonstrating up to 500% bandwidth extension with no loss of optical power. The second direction of work enhances the bandwidth of VLC receivers through new designs of ultra-low input impedance transimpedance amplifiers (TIAs), designed to be insensitive to the high photodiode capacitances (Cpd) of large area detectors. Moreover, the thesis proposes a new circuit, which modifies the traditional regulated cascode (RGC) circuit to enhance its bandwidth and gain. The modified RGC amplifier efficiently treats significant RGC inherent bandwidth limitations and is shown, through mathematical analysis, modelling and experimental measurements to extend the bandwidth further by up to 200%. The bandwidth advantage of such receivers was demonstrated in measurements, using several large area photodiodes of area up to 600 mm^2, resulting in a substantial bandwidth improvement of up to 1000%, relative to a standard 50 Ω termination. An inherent limitation of large area photodiodes, associated with internal resistive elements, was identified and ameliorated, through the design of negative resistance circuits. Altogether, this research resulted in a set of design methods and practical circuits, which will hopefully contribute to wider adoption of VLC systems and may be applied in areas beyond VLC

    Energy-Efficient Receiver Design for High-Speed Interconnects

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    High-speed interconnects are of vital importance to the operation of high-performance computing and communication systems, determining the ultimate bandwidth or data rates at which the information can be exchanged. Optical interconnects and the employment of high-order modulation formats are considered as the solutions to fulfilling the envisioned speed and power efficiency of future interconnects. One common key factor in bringing the success is the availability of energy-efficient receivers with superior sensitivity. To enhance the receiver sensitivity, improvement in the signal-to-noise ratio (SNR) of the front-end circuits, or equalization that mitigates the detrimental inter-symbol interference (ISI) is required. In this dissertation, architectural and circuit-level energy-efficient techniques serving these goals are presented. First, an avalanche photodetector (APD)-based optical receiver is described, which utilizes non-return-to-zero (NRZ) modulation and is applicable to burst-mode operation. For the purposes of improving the overall optical link energy efficiency as well as the link bandwidth, this optical receiver is designed to achieve high sensitivity and high reconfiguration speed. The high sensitivity is enabled by optimizing the SNR at the front-end through adjusting the APD responsivity via its reverse bias voltage, along with the incorporation of 2-tap feedforward equalization (FFE) and 2-tap decision feedback equalization (DFE) implemented in current-integrating fashion. The high reconfiguration speed is empowered by the proposed integrating dc and amplitude comparators, which eliminate the RC settling time constraints. The receiver circuits, excluding the APD die, are fabricated in 28-nm CMOS technology. The optical receiver achieves bit-error-rate (BER) better than 1E−12 at −16-dBm optical modulation amplitude (OMA), 2.24-ns reconfiguration time with 5-dB dynamic range, and 1.37-pJ/b energy efficiency at 25 Gb/s. Second, a 4-level pulse amplitude modulation (PAM4) wireline receiver is described, which incorporates continuous time linear equalizers (CTLEs) and a 2-tap direct DFE dedicated to the compensation for the first and second post-cursor ISI. The direct DFE in a PAM4 receiver (PAM4-DFE) is made possible by the proposed CMOS track-and-regenerate slicer. This proposed slicer offers rail-to-rail digital feedback signals with significantly improved clock-to-Q delay performance. The reduced slicer delay relaxes the settling time constraint of the summer circuits and allows the stringent DFE timing constraint to be satisfied. With the availability of a direct DFE employing the proposed slicer, inductor-based bandwidth enhancement and loop-unrolling techniques, which can be power/area intensive, are not required. Fabricated in 28-nm CMOS technology, the PAM4 receiver achieves BER better than 1E−12 and 1.1-pJ/b energy efficiency at 60 Gb/s, measured over a channel with 8.2-dB loss at Nyquist frequency. Third, digital neural-network-enhanced FFEs (NN-FFEs) for PAM4 analog-to-digital converter (ADC)-based optical interconnects are described. The proposed NN-FFEs employ a custom learnable piecewise linear (PWL) activation function to tackle the nonlinearities with short memory lengths. In contrast to the conventional Volterra equalizers where multipliers are utilized to generate the nonlinear terms, the proposed NN-FFEs leverage the custom PWL activation function for nonlinear operations and reduce the required number of multipliers, thereby improving the area and power efficiencies. Applications in the optical interconnects based on micro-ring modulators (MRMs) are demonstrated with simulation results of 50-Gb/s and 100-Gb/s links adopting PAM4 signaling. The proposed NN-FFEs and the conventional Volterra equalizers are synthesized with the standard-cell libraries in a commercial 28-nm CMOS technology, and their power consumptions and performance are compared. Better than 37% lower power overhead can be achieved by employing the proposed NN-FFEs, in comparison with the Volterra equalizer that leads to similar improvement in the symbol-error-rate (SER) performance.</p

    ECOS 2012

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    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

    Second-Order Enhanced Coupling Strength Grating Out-Couplers for a Monolithic Laser-Electro-Absorption Modulator

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    Conventional grating out-couplers in III-V waveguides typically require lengths of several hundreds of microns to outcouple 50 to 90% of the incident optical power. Enhanced coupling strength (ECS) gratings, which reduce the out-coupler grating length to tens of microns, have a large relative permittivity difference between the materials on either side of the grating boundary along with a high index cover layer. With appropriately chosen permittivity and layer thicknesses, the addition of a cover layer “pulls” the peak of the optical mode towards the grating region, resulting in a significant increase in the grating confinement factor. The resulting ECS out-coupler is short, highly efficient, and can be integrated with other III-V optical components, including horizontal cavity lasers and modulators. The theoretical dependence of the magnitude and spectral width of the out-coupled power as a function of cover layer thickness, low index material thickness, grating depth, and duty cycle is shown using a Floquet-Bloch analysis for two different ECS grating geometries. The design of a high-speed datacom transmitter with ECS grating reflectors and an ECS grating out-coupler is discussed. The proposed laser with an integrated electro-absorption modulator (Laser-EAM) theoretically provides Pulse Amplitude Modulation 2-Level (PAM-2) data rates in excess of 100Gbps with lower latency, less power consumption, and lower cost than existing commercial devices

    Electronic Evidence and Electronic Signatures

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    In this updated edition of the well-established practitioner text, Stephen Mason and Daniel Seng have brought together a team of experts in the field to provide an exhaustive treatment of electronic evidence and electronic signatures. This fifth edition continues to follow the tradition in English evidence text books by basing the text on the law of England and Wales, with appropriate citations of relevant case law and legislation from other jurisdictions. Stephen Mason (of the Middle Temple, Barrister) is a leading authority on electronic evidence and electronic signatures, having advised global corporations and governments on these topics. He is also the editor of International Electronic Evidence (British Institute of International and Comparative Law 2008), and he founded the innovative international open access journal Digital Evidence and Electronic Signatures Law Review in 2004. Daniel Seng (Associate Professor, National University of Singapore) is the Director of the Centre for Technology, Robotics, AI and the Law (TRAIL). He teaches and researches information technology law and evidence law. Daniel was previously a partner and head of the technology practice at Messrs Rajah & Tann. He is also an active consultant to the World Intellectual Property Organization, where he has researched, delivered papers and published monographs on copyright exceptions for academic institutions, music copyright in the Asia Pacific and the liability of Internet intermediaries

    Lumped silicon photonic Mach-Zehnder modulators for high-speed optical interconnects

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    The boom in worldwide internet connectivity and cloud services has caused unprecedented need for high-bandwidth connections between and within data centres. Silicon photonics is becoming the platform of choice to provide low-cost, large-volume production of future optical transceivers. However, the scale of modern data centres introduces challenges of speed, reach and, crucially, energy consumption for these devices. Silicon photonic Mach-Zehnder modulators (MZMs) are one possibility for providing electrical-to-optical conversion at the transmit side of such fibre-optic links. In this thesis, comprehensive investigation is carried out into lumped MZMs, specifically, as their unterminated, capacitive load holds promise for lower power consumption than more typical travelling-wave MZMs with resistive terminations. Detailed characterisations and simulations of dual-drive silicon photonic lumped MZMs are made to investigate the key trade-off of modulation bandwidth and drive voltage. Drivers with low source impedance are investigated as a means of boosting lumped MZM bandwidths, while advanced modulation formats such as four-level pulse-amplitude modulation (PAM4) and electrical duobinary modulation (EDB) are also leveraged to provide more spectrally-efficient signals. In particular, experimental demonstration is made of a novel low-impedance, switched-capacitor PAM4 driver for a lumped MZM in a 30 Gb/s silicon photonic link over 10 km of optical fibre. Simulations are carried out to optimise the bias and doping levels of lumped MZMs used with such drivers. Predistortion methods are investigated through experiments and simulations as alternative ways to increase the bandwidth. A simple first-order FIR filter is shown experimentally to enable 25 Gb/s NRZ modulation with a low-bandwidth MZM, while more optimised precompensation enables 50 Gb/s PAM4 and EDB. Finally, simulations using an accurate equivalent circuit model for the lumped MZM demonstrate the potential for a well-designed driver with lowered source impedance and controlled amounts of inductive peaking to reduce the need for transmitter-side precompensation
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