As the number of people with diabetes continues to increase, research efforts improving glucose testing methods and devices are under way to improve outcomes and quality of life for diabetic patients. This dissertation describes the design and testing of a Data Acquisition Unit (DAU) providing low noise photocurrent spectra for use in a continuous glucose monitoring system. The goal of this research is to improve the signal to noise ratio (SNR) of photocurrent measurements to increase glucose concentration measurement accuracy. The glucose monitoring system consists of a portable monitoring device and base station. The monitoring device measures near infrared (IR) absorption spectra from interstitial fluid obtained by microdialysis or ultrafiltration probe and transmits the spectra to a base station via USB or a ZigBee radio link. The base station utilizes chemometric calibration methods to calculate glucose concentration from the photocurrent spectra. Future efforts envisage credit card-sized monitoring devices. The glucose monitor system measures the optical absorbance spectrum of an interstitial fluid (ISF) sample pumped through a fluid chamber inside a glucose sensor. Infrared LEDs in the glucose sensor illuminate the ISF sample with IR light covering the 2.2 to 2.4 micron wavelength region where glucose has unique features in its absorption spectrum. Light that passes through the sample propagates through a linearly variable bandpass filter and impinges on a photodiode array. The center frequency of the variable filter is graded along its length such that the filter and photodiode array form a spectrometer. The data acquisition unit (DAU) conditions and samples photocurrent from each photodiode channel and sends the resulting photocurrent spectra to the Main Controller Unit (MCU). The MCU filters photocurrent samples providing low noise photocurrent spectra to a base station via USB or Zigbee radio link. The glucose monitoring system limit of detection (LOD) from a single glucose sensor wavelength is 5.8 mM with a system bandwidth of 0.00108 Hz. Further analysis utilizing multivariate calibration methods such as the net analyte signal method promise to reduce the glucose monitoring system LOD approaching a clinically useful level of approximately 2 mM.

<p>The work describes the development of a reliable device for profiling anion beam in the intensity cross section. A sensor head consisting of a Faradaycup in combination with a Channel Electron Multiplier was designedand built together with electronics including power supply and front endelectronics. The design was chosen considering financial and long term lifeaspects. Testing, first calibration and error analysis were done using the ionbeam facilities where the unit is supposed to be installed permanently. Theprofiling system performed as designed and the profile of the ion beam couldbe measured reliably with an accuracy down to the femto ampere range.</p>

The work describes the development of a reliable device for profiling anion beam in the intensity cross section. A sensor head consisting of a Faradaycup in combination with a Channel Electron Multiplier was designedand built together with electronics including power supply and front endelectronics. The design was chosen considering financial and long term lifeaspects. Testing, first calibration and error analysis were done using the ionbeam facilities where the unit is supposed to be installed permanently. Theprofiling system performed as designed and the profile of the ion beam couldbe measured reliably with an accuracy down to the femto ampere range.

Steady increases in the bandwidth requirements of access networks and local area networks have created a need for short-reach links supporting data rates of 10 Gb/s and larger. Server applications and data center applications too require such links. The primary challenge for these links lies in the reduction of the cost while retaining or improving the performance. Traditionally, multimode fiber (MMF) has satisfied these needs because of its low installation cost resulting from the alignment tolerance associated with the large core size. However, in view of the ever-increasing performance requirements, extraction of the best performance requires a holistic view of the channel that involves global optimization of transmitter, fiber, receiver performance and signaling strategies. The optimization results in a channel impairment mitigation technique that is a combination of optical, opto-electronic, and electronic methods. Both glass and plastic MMF links have been addressed in this work and many of the advances apply equally to both media. One example that applies strictly to glass MMF is the use of Raman amplification to not only combat attenuation but to reduce intersymbol interference (ISI). Raman amplification was demonstrated as an optical channel impairment mitigation technique enabling multi-km, multi-Gb/s transmission over glass-MMF. We demonstrated both numerically and experimentally that a power penalty reduction of 1.4 dBo can be achieved for 10 Gb/s transmission over 9 km of 62 micron glass MMF with a Raman pump power 250 mW. In recent years, plastic optical fiber (POF) has emerged as a potentially lower cost alternative to glass-MMF in enabling high performance links. The primary objective of this research is to explore the possibilities and develop low-cost, short-reach, high-data-rate POF-links. Using a comprehensive multimode fiber model, we showed that strong mode coupling, together with a reasonably accurate refractive index profile enables 40 Gb/s transmission over 200 m of graded-index POF. We experimentally demonstrated 40 Gb/s error-free transmission over 100 m of graded index perfluorinated POF (GI-PF-POF). We also demonstrated that even larger core (120 micron) GI-PF-POF can support >10 Gb/s over 100 m length. We numerically computed and experimentally measured the differential modal delay of GI-PF-POF to demonstrate that the available bandwidth is nearly independent of the launch conditions. Therefore, the alignment tolerance at the transmitter is increased resulting in a dramatically reduced packaging cost at the transmitter. However, the large-core POF increases the difficultly in capturing of the light efficiently onto a detector and results in optical power penalty and associated modal noise. To solve this, we have designed and developed a 10 Gb/s photoreceiver consisting of a large (100 micron diameter) GaAs PIN photodetector and a regulated cascade input based transimpedance amplifier (TIA) with low input impedance. Thus, a low-cost, alignment-tolerant, high-data-rate link is realized that uses a high-power, high-speed vertical cavity surface emitting laser (VCSEL) transmitter, large-core, high-speed GI-PF-POF, and the developed receiver.

This thesis examines the design of high speed transimpedance amplifiers (TIAs) in low cost complimentary metal oxide semiconductor (CMOS) technology. Due to aggressive scaling, CMOS has become an attractive technology for high speed analog circuits. Besides the cost advantage, CMOS offers the potential for higher levels of integration since the analog circuits can be integrated with digital electronics on the same substrate. A 2.5 Gbps transimpedance amplifier fabricated using 0.18 um CMOS technology is presented. The TIA uses a shunt-shunt feedback topology with a cascode gain stage. Measurements of the transimpedance gain, group delay, and common mode rejection ratio are presented for the TIA and show a good match to simulated results. The noise of the TIA was characterized by measuring the noise parameters of the TIA. The noise parameters are then used to determine the input referred noise current spectral density. A 10 Gbps transimpedance amplifier fabricated using 0.18 um CMOS technology is also presented. This TIA uses a shunt-shunt feedback topology with a common source gain stage. In order to achieve the required bandwidth, the TIA uses a bandwidth extension technique called shunt-series inductive peaking. A discussion of the different methods of bandwidth extension using inductive peaking is included, and the optimal configurations for maximally flat responses are shown for shunt inductive peaking,series inductive peaking, and shunt-series inductive peaking. The TIA circuit topology is optimized using a novel noise analysis that uses a high frequency noise model for the transistor. The optimum transistor size and bias current are determined to minimize the amplifier noise. Unfortunately differential measured results are not available due to a stability problem in the amplifier. The cause of this instability is further explored and modifications to solve the problem are discussed. Single-ended results are presented and show reasonable agreement with simulated results. Differences in the results are attributed to poor modelling of the on-chip spiral inductors. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-07-16 13:34:41.46

Circuits to extend operation data-rate of a optical receiver is investigated in the dissertation. A new input-stage topology for a transimpedance amplifier (TIA) is designed to achieve 50% higher data-rate is presented, and a new architecture for clock recovery is proposed for 50% higher clock rate. The TIA is based on a gm-boosted common-gate amplifier. The input-resistance is reduced by modifying a transistor at input stage to be diode-connected, and therefore lowers R-C time constant at the input and yielding higher input pole frequency. It also allows removal of input inductor, which reduces design complexity. The proposed circuit was designed and fabricated in 32 nm CMOS SOI technology. Compared to TIAs which mostly operates at 50 GHz bandwidth or lower, the presented TIA stage achieves bandwidth of 74 GHz and gain of 37 dBohms while dissipating 16.5 mW under 1.5V supply voltage. For the clock recovery circuit, a phase-locked loop is designed consisting of a frequency doubling mechanism, a mixer-based phase detector and a 40 GHz voltage-controlled oscillator. The proposed frequency doubling mechanism is an all-analog architecture instead of the conventional digital XOR gate approach. This approach realizes clock-rate of 40 GHz, which is at least 50% higher than other circuits with mixer-based phase detector. Implemented with 0.13-μm CMOS technology, the clock recovery circuit presents peak-to-peak clock jitter of 2.38 ps while consuming 112 mW from a 1.8 V supply. / Ph. D. / This dissertation presents two electronic circuits for future high-speed fiber optics applications. A receiver in a optical communication systems includes several circuit blocks serving various functions: (1) a photodiode for detecting the input signal; (2) a transimpedance amplifier (TIA) to amplify the input signal; (3) a clock and data recovery block to re-condition the input signal; and (4) digital signal processing. High speed integrated circuits are commonly fabricated in SiGe or other high electron mobility semiconductor technologies, but receiver circuits based on Silicon using complementary metal oxide semiconductor (CMOS) technology has gained attention in open literatures due to its advantage of integrating signal processing . This dissertation shows a TIA circuit and a clock recovery circuit designed and implemented in CMOS technology. The TIA circuit is based on a ”g_m-boosted common-gate amplifier” topology, and a slight modification at the input of the topology is proposed. Implemented in 32nm SOI CMOS technology, the TIA measures bandwidth that achieved 100 Gb/s bandwidth. The bandwidth is increased by at least 48% when compared with state-of-the-art CMOS TIA’s. The clock recovery circuit is a phase-locked loop with a mixer as the phase detector. An architectural change of replacing the conventional frequency doubling mechanism is proposed. The circuit is implemented in 0.13 µm CMOS technology, and it achieved 40 GHz clock rate with 40 Gb/s data input, which is about 40% increase of clock rate compared to state-of-the-art clock recovery circuits of similar architecture.

This work is focused on free space optical communication in visible electromagnetic spectrum known as visible light communication (VLC). Basic parameters of standard IEEE 802.15.7, advantages and disadvantages are discussed in the theoretical part of this work. Furthermore, optical link and it´s parts are described. The largest part of the work is focused on design and simulation of optical receiver for visible spectrum. Selection of component, noise and SNR calculation is discussed as well. This work also includes calculation of power energy in different parts of optical connection, PCB design of optical receiver, transmitters and power supply and output board. Behavior and parameters of electronic circuits, components and optical connection are explored, measured and compared with theoretical values.

Measuring low electrical currents with high precision is critical across various fields, particularly in applications like microfluidic biosensing. Traditional digital multimeters (DMMs) are inadequate for low current measurements due to their high input burden and limited resolution. Therefore, more sensitive instruments like electrometers and picoammeters are often required but are typically expensive. This thesis explores the design and construction of a cost-effective, portable, and user-friendly picoammeter based on a transimpedance amplifier (TIA), capable of measuring currents in the picoampere (pA) range with a resolution of 1-5 pA and minimal noise. The constructed picoammeter has a maximum input current range of ±1.5 nA.  A prototype was built on a soldering board to validate the design, which was then translated into a practical printed circuit board (PCB) layout. The device is powered by batteries to ensure low noise levels and enable isolated operation. An Arduino microcontroller was used to interface with the circuit, manage data acquisition, and enable real-time visualisation of the measured current data on a computer.  Simulation results confirmed the theoretical performance of the circuit, and experimental validation showed RMS noise levels of less than 0.3 pA under controlled conditions and up to 3 pA when measuring streaming currents from a microchip. Despite a slight underestimation of input currents due to resistor tolerances, calibration adjustments successfully corrected these discrepancies.  The total cost of the materials used in constructing the picoammeter was significantly less than the cost of commercially available devices. While commercial devices offer higher precision and additional functionalities, the developed picoammeter demonstrates how application-focused solutions can provide comparable accuracy and noise characteristics to commercial devices for a fraction of the price.

Inter-chip input-output (I/O) communication bandwidth demand, which rapidly scaled with integrated circuit scaling, has leveraged equalization techniques to operate reliably on band-limited channels at additional power and area complexity. High-bandwidth inter-chip optical interconnect architectures have the potential to address this increasing I/O bandwidth. Considering future tera-scale systems, power dissipation of the high-speed I/O link becomes a significant concern. This work presents a design flow for the power optimization and comparison of high-speed electrical and optical links at a given data rate and channel type in 90 nm and 45 nm CMOS technologies. The electrical I/O design framework combines statistical link analysis techniques, which are used to determine the link margins at a given bit-error rate (BER), with circuit power estimates based on normalized transistor parameters extracted with a constant current density methodology to predict the power-optimum equalization architecture, circuit style, and transmit swing at a given data rate and process node for three different channels. The transmitter output swing is scaled to operate the link at optimal power efficiency. Under consideration for optical links are a near-term architecture consisting of discrete vertical-cavity surface-emitting lasers (VCSEL) with p-i-n photodetectors (PD) and three long-term integrated photonic architectures that use waveguide metal-semiconductor-metal (MSM) photodetectors and either electro-absorption modulator (EAM), ring resonator modulator (RRM), or Mach-Zehnder modulator (MZM) sources. The normalized transistor parameters are applied to jointly optimize the transmitter and receiver circuitry to minimize total optical link power dissipation for a specified data rate and process technology at a given BER. Analysis results shows that low loss channel characteristics and minimal circuit complexity, together with scaling of transmitter output swing, allows electrical links to achieve excellent power efficiency at high data rates. While the high-loss channel is primarily limited by severe frequency dependent losses to 12 Gb/s, the critical timing path of the first tap of the decision feedback equalizer (DFE) limits the operation of low-loss channels above 20 Gb/s. Among the optical links, the VCSEL-based link is limited by its bandwidth and maximum power levels to a data rate of 24 Gb/s whereas EAM and RRM are both attractive integrated photonic technologies capable of scaling data rates past 30 Gb/s achieving excellent power efficiency in the 45 nm node and are primarily limited by coupling and device insertion losses. While MZM offers robust operation due to its wide optical bandwidth, significant improvements in power efficiency must be achieved to become applicable for high density applications.

La thèse porte sur les mesures de courants transitoires limités par la charge d'espace dans des films minces organiques (épaisseur < 500 nm). Ce type de films est souvent utilisé dans des applications dans le domaine de l'électronique organique comme couches actives semi-conductrices. Le transport électrique dans ces films dépend en premier lieu du transport des porteurs de charge dans le milieu massif et de leur piégeage, mais aussi de l'efficacité de l'injection des porteurs de charges à partir des électrodes métalliques. L'ensemble est de plus conditionné par le taux de désordre inhérent aux matériaux organiques. L'approche qui consiste à utiliser la mesure de courants transitoires est extrêmement attractive car elle permet en principe de fournir une information sur tous ces aspects à l'issue d'un seul type de mesure. Dans ce cadre, trois contributions principales peuvent être dégagées de la thèse. 1) Tout d'abord, nous avons validé un montage expérimental qui utilise un amplificateur à transfert d'impédance pour la mesure des courants transitoires limités par la charge d'espace. Ce type de montage s'avère supérieur au circuit de pont électrique le plus largement utilisé jusqu'à maintenant car il présente une meilleure sensibilité en courant, une meilleure bande passante, et ne nécessite aucun réglage ni de la symétrie du pont ni de l'ajustement de la taille de l'échantillon. On a pu démontrer que le pic de courant de déplacement initial, qui sature l'amplificateur au tout début de la mesure n'introduit pas d'erreur dans la mesure de la mobilité. 2) Ensuite concernant l'étude plus spécifique du transport dans un dendrimère à base de tri-arylamine, les réponse en courant obtenues expérimentalement se sont avérées en bon accord avec le modèle de déplacement-diffusion. Cependant, la troisième leçon que nous avons apprise est que l'obtention d'un tel accord a nécessité que soient très bien définies les conditions initiales tant de l'expérience que de la simulation et qu'un modèle théorique le plus complet possible de l'échantillon soit considéré. Pour le dendrimère ce modèle a dû prendre en compte l'effet de la barrière au contact et les effets de piégeage. Un accord encore meilleur a été obtenu en intégrant de surcroit les effets de désordre. 3) La complète impossibilité d'obtenir un bon accord sans un modèle physique complet de l'échantillon indique que les paramètres liés au piégeage, à la barrière au contact et à la mobilité peuvent véritablement être ajustés sans aucune ambigüité. Ainsi, une caractérisation électrique complète en cohérence avec la simulation a pu être obtenue à l'issue d'un seul type de mesures. Les résultats obtenus, alliant à la fois amélioration technique et support numérique, témoignent de la grande utilité de cette technique de mesure de courant transitoire limité par la charge d'espace pour caractériser en détails le transport dans les films minces organiques. / The thesis concerns space-charge-limited transient current measurements in thin (le500 nm) organic films. Such films find important applications in organic electronics, where they are referred to as organic semiconductor layers. Electrical transport in such films depends on bulk charge carrier transport and trapping, as well efficiency of charge carrier injection from electrodes. These, are all in turn depend on disorder inherent to organic materials. The transient measurement approach is very attractive, as it can, in principle, deliver information on all these aspects in one single measurement. In the thesis, three main contributions are presented. 1) A transimpedance amplifier based setup for space-charge-limited current transient measurement is validated. This type of setup is superior to the widely used bridge circuit, notably because of better current sensitivity, bandwidth, no need for bridge symmetry and no need for per sample adjustment. It is demonstrated that initial displacement current spike, which saturates the amplifier at the beginning of measurement, does not introduce error in the measurement of mobility. 2) A dendrimer molecule has been investigated. Experimental current responses are shown to be in agreement with the drift-diffusion model. However, obtaining agreement requires well defined initial conditions in experiment as well as in simulation, and also complete theoretical model of the sample. In the case of dendrimer, this model had to take into account both contact barrier and trapping effects. Furthermore, better agreement was obtained when taking disorder effects into account. 3) The impossibility of obtaining any agreement without complete physical model of the sample indicates that trapping, contact barrier and mobility parameters could be fitted without ambiguity. Therefore, complete electrical characterization consistent with simulation can be obtained using the transient technique. The results obtained further increase well known usefulness of transient space-charge-limited current characterization of thin organic films.