This thesis work is mainly focused on studying RF performance degradation of a low noise amplifier (LNA) circuit due to hot carrier effect (HCE) in both the weak and strong inversion regions. Since the figures of merit for the RF circuit characterization are gain, noise figure, input, and output matching, the LNA RF performance drift is evaluated in a Cadence SpectreRF simulator subject to these features. This thesis presents hot carrier induced degradation results of an LNA to show that the HCE phenomenon is one of the serious reliability issues in the aggressively scaled RF CMOS design, especially for long-term operation of these devices. The predicted degradation from simulation results can be used design reliable CMOS RF circuits.

Noise in electronic circuits can sometimes cause problems. It is especially problematic in for example high sensitive sensors and high end audio and video equipment. In audio and video equipment the noise will make its way into the sound and picture reducing the overall quality. Sensors that are constructed to sense extremely small changes can only pick up changes larger than the noise floor of the circuit. By lowering the noise, sensors can achieve higher accuracy.  This thesis presents an ultra low noise solution of the biasing circuitry to the bolometer used in one of FLIR Systems high end cameras. The bolometer uses different adjustable direct current voltage sources and is extremely sensitive to noise. The purpose is to improve the picture quality and the thermal measurement resolution. A prototype circuit was constructed and in the end of the thesis a final circuit with successful result will be presented.

This thesis describes a unique approach of turning on and off transistor cores to reconfigure low-noise amplifiers. A small footprint single-pole, single-throw switch is optimized for low insertion loss and high isolation. A narrowband (non-switchable) LNA is developed as a basis of comparison for reconfigurable designs. The optimized switch is incorporated into different switchable transistor core architectures. These architectures are investigated to determine their ability to reconfigure amplifier performance. One switchable transistor core topology is integrated into a cascode LNA design. An in depth stability analysis employing the S-probe technique is used to help improve the reliability of the cascode design. In addition, a single-pole, double-throw transmit/receive switch, as well as a deserializer are developed to help support the LNA block in a reconfigurable phased-array radar system. This type of flexible radar design is very beneficial in challenging electromagnetic environments.

No description available.

Submitted in fulfillment of the academic requirements for the Master’s Degree of Technology: Electrical Engineering – Light Current, Durban University of Technology, 2012. / The development of a transit radio telescope at the hydrogen line frequency of 1420 MHz is described. The telescope antenna uses a 5 m diameter parabolic reflector with an estimated efficiency of 50 % and an F/D ratio of 0.5. The gain of the antenna at 1420 MHz (wavelength of 21.1 cm) is approximately 35 dB with a beamwidth of approximately 3°. The antenna is mounted on a concrete beam at the first floor level, running between two 5 floor tower blocks on the Steve Biko campus of the Durban University of Technology. The majority of the components of the radio telescope antenna and receiver were designed and manufactured at the Durban University of Technology by students of the Departments of Mechanical and Electronic Engineering. The measured sensitivity of the receiver is approximately -94 dBm with a bandwidth of approximately 80 MHz. Radio sources successfully detected by the radio telescope include the Sun, the Moon, Sagittarius A, Centaurus A and Vela X.

International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, California / The Very Large Array (VLA) radio telescope, located in west-central New Mexico, obtains high-resolution radio images of astronomical objects by using Fourier aperture synthesis with 27 antennas. With the addition of X-band to its receiving capabilities by 1989, and when arrayed with the Goldstone Deep Space Communications Complex (GDSCC), the VLA will double the Deep Space Network (DSN) receiving aperture in the U. S. longitude for signals from Voyager 2 at Neptune. This paper describes the VLA and the installation of the X-band system, its operation and performance for Voyager data reception, and its capabilities for other science at X-band.

Envisioning novel fully monolithic fiber-optical devices, this dissertation investigates four fiber optical devices both, active and passive, that contribute to the goal of further integrating and miniaturizing fiber optics. An all phosphate glass fiber laser was designed in an effort to reduce laser intensity noise by reducing cavity losses and low mechanical strength that arise from intra-cavity fusion splices between silica fiber Bragg gratings (FBG) and phosphate active fiber in state of the art phosphate single frequency fiber lasers. Novel phosphate glass based FBGs have been fabricated utilizing high intensity laser pulses at 193 nm and a phase-mask. Net reflectivities of up to 70 % and a bandwidth of 50 pm have been achieved in the FBGs. The laser design comprised two of the novel FBGs and a short section of Er³⁺Yb³⁺ phosphate fiber to form a distributed Bragg reflector (DBR) laser. The performance of the new laser has been compared to a conventional phosphate fiber laser. Particular focus was put on the laser intensity noise due to its dependence on intra-cavity losses. Relative intensity noise (RIN) amplitudes of -80 dB/Hz have been measured for both lasers when operating at comparable output powers. For similar levels of absorbed pump power the relaxation oscillation frequencies (ROF) were shifted towards lower frequencies in the new laser. ExcessFBG scattering losses and mode-field miss-match between the active and passive fiber limited the output power of the new laser to 16 mW compared to 140 mW in the conventional laser. A monolithic all-phosphate glass fiber laser with up to 550 mW output power that is operating at a single longitudinal mode and exhibiting narrow linewidth is presented. The laser cavity has been formed by inscribing FBGs directly into heavily Er³⁺Yb³⁺ doped phosphate glass fiber using femtosecond laser pulses and a phase mask, completely eliminating the need for intra-cavity fusion splices. A linewidth of less than 60 kHz and relaxation oscillation peak amplitudes below -100 dB/Hz without active suppression of RIN have been measured. The compact form factor and higher output power combined with the low noise and narrow linewidth characteristic make this laser an ideal candidate for ranging, interferometry and sensing applications. Strong and robust Bragg gratings in optical fiber fabricated from highly photosensitive photo-thermo-refractive (PTR) glass are demonstrated. The fibers were drawn at 900 °C from a machined PTR-glass preform. A low power two beam interference pattern from a continuous wave (cw) He-Cd laser with a wavelength of 325 nm was used to write gratings into the fibers, achieving peak grating strengths of 20 dB and a spectral width of 45 pm. The gratings showed no sign of degradation when exposed to a high temperature environment of 425 °C for several hours. This is significantly higher when compared to standard Telecom FBGs which are rated for operation temperatures below 200 °C. A detailed study of novel mode-field adapters (MFA) based on multi-mode interference in graded index multi-mode fibers (GIMF) is presented. MFAs are often used in cases when low coupling losses between single mode fibers with very different mode-field diameters are needed. Here a new type of MFAs has been fabricated and characterized from a selection of commercially available single mode and graded index fibers. Compared to existing techniques the presented MFAs can be fabricated very quickly and are not limited to certain fiber types. Insertion losses of 0:5 dB over a spectral range of several hundred nm have been obtained with an ultra compact MFA with a length of 275 μm.

Durant ces vingt dernières années l'émergence des technologies MEMS a rendu possible l'intégration de capteurs au sein de systèmes complexes de taille réduite. Quelques-uns de ces capteurs se retrouvent dans des dispositifs tels que les téléphones mobiles, GPSs, ordinateurs portables… Il existe néanmoins une contrainte majeure, quand à l’utilisation de capteurs dans les applications fonctionnant sur batterie : leurs «consommation». En effet du fait de cette contrainte la plus part des capteurs développés de nos jours sont basés sur des modes de transduction capacitif limitant ainsi la consommation mais par la même occasion complexifiant lourdement la conception de l’élément sensible. Cette complexité de réalisation de l’élément sensible se répercute donc sur le prix du produit final. Le meilleur moyen de diminuer le prix de revient d’un capteur est l’utilisation d’une technologie de transduction qui permet de diminuer la complexité structurelle du capteur. La transduction résistive répond bien à ce problème, cependant les structures de conditionnement de signal les plus utilisées dissipent une puissance excessive. Cette thèse propose donc l’étude d’une structure électronique faible bruit / faible consommation innovante (le pont Actif) permettant le conditionnement de signaux issus de capteurs résistifs. Les critères d’évaluation du pont actif sont ici le gain, le bruit intrinsèque de l’électronique (facteur limitant de la résolution) et, le plus important, la consommation globale du capteur (éléments sensible + électronique de traitement). / Since resistive sensors exist, the Wheatstone bridge has been the most commonly used conditioningand read-out architecture. Even with the development of MEMS in the last decade, the Wheatstonebridge remains the preferred solution to transpose a physical magnitude into the electrical domain assoon as a resistive transduction method is used. Nevertheless the Wheatstone bridge introduces amajor issue for low-power sensors, the dependence of resolution to power consumption. Moreover,the output signal is directly proportional to the supply voltage. Finally, power consumption is theprice to pay for high resolution in a Wheatstone bridge.Low-power requirement, in mobile applications, is probably one of the main reasons to explain whycapacitive transduction has been preferred for many MEMS. Indeed, even if the fabrication process isoften more complex than for resistive sensors, the power consumption of capacitive transduction isfar below the one of dissipative resistor-based sensors.In order to extend the potential application of resistive MEMS, a power-efficient interface circuit isrequired. My PhD thesis deals with the design and manufacturing of an innovative conditioning andread-out interface for resistive MEMS sensor. The proposed structure includes a digital offsetcompensation for robustness to process, voltage, temperature variations, and/or analog to digitalconversion. Results demonstrate good resolution to power consumption ratio and a good immunityto environmental parameters. Experimental results on a fully integrated CMOS/MEMS sensor finallydemonstrate the efficiency of this promising read-out architecture called The active bridge.

Esta dissertação apresenta o projeto de um amplificador de baixo ruído (LNA) para aplicação em 2,4 GHz na tecnologia CMOS 0,35 µm. A metodologia baseia-se na obtenção das dimensões dos dispositivos do circuito considerando o consumo de potência e o desempenho em relação ao ruído. Os resultados mostram que a metodologia implementada é eficaz no projeto de um LNA quando se comparam os resultados obtidos nos cálculos com os resultados obtidos no simulador. A expressão de corrente que considera canal curto impõe maior precisão nos resultados, pois se aplica o ajuste de curva com a curva de corrente obtida pelo simulador. Isto permite maior precisão nos resultados dos cálculos de ruído. O fluxo do projeto baseia-se na implementação de dispositivos ideais obtidos de projeto com o propósito de fazer-se comparações dos resultados de cálculos com as simulações, então, usa-se dispositivos reais e ajusta-se o circuito para encontrar melhores desempenhos quanto às especificações. Os resultados mostram a necessidade de ajuste do circuito quando inserido o modelo do indutor para que se consiga desempenhos próximos dos obtidos inicialmente. Em seguida, realiza-se o layout do circuito e sua extração parasitária para fins de fabricação. Verifica-se que a metodologia apresentada é capaz de direcionar a um projeto de um LNA na tecnologia com resultados finais satisfatórios de ganho, ruído e consumo. Assim os resultados esperados são 14,66 dB de ganho, 1,9 dB de fator de ruído e 2,99 mA de consumo de corrente (9,87 mW em 3,3 V de alimentação) ambos no primeiro estágio. / This work presents the design of a low-noise amplifier (LNA) for application at 2.4 GHz using CMOS 0.35 µm technology. The methodology is based on obtaining the dimensions of the devices taking into account of power consumption and performance on noise. Results show that the implemented methodology is efficient in the design of LNAs when it compares results obtained by calculation and simulation. The expression of current that considers short-channel effects increases the precision of results because curve fitting is applied with the current of the simulator. This permits precision on the results of the noise calculation. The design-flow firstly bases on implementation of ideal devices obtained by design on purposes of doing comparisons between calculated and simulated results, then real devices is used and the circuit is fixed to find better performance regarding the specifications. The results showed the necessity of adjusts in the circuit when the inductor is inserted to reach a closer initial performance. Afterwards, the layout of the circuit and its parasitic extraction are worked out for purposes of fabrication. It is verified that this methodology is capable of directing to the design of LNAs using the proposed technology with satisfactory final results of gain, noise and power consumption. Therefore, the expected results are 14,66 dB of gain, 1,9 dB of noise figure, 2,99 mA of current consumption (9,87 mW within 3.3 V of supply voltage) both of them at first stage.

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.