CMOS active pixel sensors (APS) have shown competitive performance with charge-coupled device (CCD) and offer many advantages in cost, system power reduction and on-chip integration of VLSI electronics. Among CMOS image sensors, sensors with logarithmic pixels are particularly applicable for outdoor environment where the light intensity varies over a wide range. They are also randomly accessible in both time and space. A major drawback comes from process variations during fabrication. This gives rise to a considerable fixed pattern noise (FPN) which deteriorates the image quality. In this thesis, a technique that greatly reduces FPN using on-chip calibration is introduced. An image sensor that consists of 64x64 active pixels has been designed, fabricated and tested. Pixel pitch is 18um x 19.2um? and is fabricated in a 0.5-um? CMOS process. The proposed pixel circuit considerably reduces the FPN as predicted in theoretical analysis. The measured FPN value is 2.29% of output voltage swing and column-wise FPN is 1.49% of mean output voltage over each column.

CMOS active pixel sensors (APS) have shown competitive performance with charge-coupled device (CCD) and offer many advantages in cost, system power reduction and on-chip integration of VLSI electronics. Among CMOS image sensors, sensors with logarithmic pixels are particularly applicable for outdoor environment where the light intensity varies over a wide range. They are also randomly accessible in both time and space. A major drawback comes from process variations during fabrication. This gives rise to a considerable fixed pattern noise (FPN) which deteriorates the image quality. In this thesis, a technique that greatly reduces FPN using on-chip calibration is introduced. An image sensor that consists of 64x64 active pixels has been designed, fabricated and tested. Pixel pitch is 18um x 19.2um? and is fabricated in a 0.5-um? CMOS process. The proposed pixel circuit considerably reduces the FPN as predicted in theoretical analysis. The measured FPN value is 2.29% of output voltage swing and column-wise FPN is 1.49% of mean output voltage over each column.

We report on experiments with a mobile robot using one vision process (forward motion vision) to calibrate another (stereo vision) without resorting to any external units of measurement. Both are calibrated to a velocity dependent coordinate system which is natural to the task of obstacle avoidance. The foundations of these algorithms, in a world of perfect measurement, are quite elementary. The contribution of this work is to make them noise tolerant while remaining simple computationally. Both the algorithms and the calibration procedure are easy to implement and have shallow computational depth, making them (1) run at reasonable speed on moderate uni-processors, (2) appear practical to run continuously, maintaining an up-to-the-second calibration on a mobile robot, and (3) appear to be good candidates for massively parallel implementations.

The thesis is composed of tow topics: a high performance current-balancing instrumentation amplifier (IA) for ECG (Electrocardiogram) monitoring systems and an IA with CMRR (Common-Mode Rejection Ratio) self-calibration. In the first topic, a high common mode rejection ratio (CMRR) and a low input referred noise instrumentation amplifier (IA) is presented for ECG applications. A high pass filter (HPF) with a small-Gm OTA using a current division technique is employed to attain small transconductance, which needs only a small capacitor in the HPF such that the integration on silicon is highly feasible. The proposed design is carried out by TSMC standard 0.18 £gm CMOS technology. CMRR is found to be 127 dB and the voltage gain is 45 dB according to the simulation results. The second topic discloses an instrumentation amplifier with CMRR self-calibration capability. The propose design is also carried out by TSMC standard 0.18 £gm CMOS technology. To achieve a CMRR of more than 80 dB, a calibration resistance string and a detection circuit have been utilized. The DC gain of the proposed design is 60 dB and the frequency bandwidth is bound in 10 KHz, which is adaptable for biomedical signal acquisition applications.

In this thesis digital control techniques for two receiver front-end components i.e. the downconverter mixer and the modulator are presented. With decrease in size of CMOS-based geometries, decrease in performance and yield of analog components has become an issue. Using the digital components on a System-on-Chip to account for the shortcoming in analog circuitry and thereby developing 'self-calibrating' systems has become a reliable way to address this issue. In the telecommunications industry, this is directly correlated to lower post-fabrication testing times, quicker product development and lower overhead costs. The first design presented is a 0.13 um CMOS mixer with variable gain capability. A Digital Assist system was put in place to extend the 3-dB bandwidth of the system using a microcontroller. An interpolation routine was used to predict the bias voltages based on variations in frequency and desired input power. The digital-to-analog converter on the microcontroller was used to set the required bias voltages. The mixer's bandwidth was extended from 12GHz to 15GHz using digital assist. The gain of the mixer with the digital assist in place could be varied from 1.2-9.8dB. The second design presented is a 5.4GHz multi-scheme modulator fabricated in 0.13 um CMOS technology. The modulator is capable of carrying out quadrature amplitude modulation as well as phase-shift keying modulation. The modulator makes use of a novel OTA design to generate a set of orthogonal basis vectors which allows for facile mapping of the modulated data on the I-Q plane. The modulator carries out modulation in 4-PSK, 8-PSK, 4-QAM and 16-QAM modes with a maximum error vector magnitude of only 8.51%. A digital assist model to attain ubiquitous operation inside a system is also presented for this modulator. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2014-05-03 13:16:06.018

MEMS gyroscopes have become an essential component in consumer, industrial and automotive applications, owing to their small form factor and low production cost. However, their poor stability, also known as drift, has hindered their penetration into high-end tactical and navigation applications, where highly stable bias and scale factor are required over long period of time to avoid significant positioning error. Improving the long-term stability of MEMS gyroscopes has created new challenges in both the physical sensor design and fabrication, as well as the system architecture used for interfacing with the physical sensor. The objective of this research is to develop interface circuits and systems for in-situ control and self-calibration of MEMS resonators and resonant gyroscopes to enhance the stability of bias and scale factor without the need for any mechanical rotary stage, or expensive bulky lab characterization equipment. The self-calibration techniques developed in this work provide 1-2 orders of magnitude improvement in the drift of bias and scale factor of a resonant gyroscope over temperature and time.

This thesis includes two topics, which are a Self-sampled ALL-MOS ASK Demodulator and a Synchronous DAC with Self-calibration. An all-MOS ASK demodulator with a wide bandwidth for lower ISM band applications is presented in the first half of this thesis. The chip area is reduced without using any passive element. It is very compact to be integrated in an SOC (system-on-chip) for wireless biomedical applications, particularly in biomedical implants. Because of low area cost and low power consumption, the proposed design is also easily to be integrated in other mobile medical devices. The self-sampled loop with a MOS equivalent capacitor compensation mechanism enlarges the bandwidth, which is more than enough to be adopted in any application using lower ISM bands. To demonstrate this technique, an ASK demodulator prototype is implemented and measured using a TSMC 0.35 £gm standard CMOS process. The second topic reveals a synchronous DAC with self-calibration. The main idea is to use a calibration circuit to overcome large error of output voltage caused by the variation of the unit capacitor. When DAC is not calibrated, INL is larger than 1.7 LSB. After calibrated, INL is improved to be smaller than 0.5 LSB. To demonstrate this technique, a DAC prototype is implemented and measured using a TSMC 0.18 £gm standard CMOS process.

No description available.

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are relatively new biomedical techniques developed during the last century, which are frequently recommended for patients with joint diseases. In spite of their success and huge popularity, the postoperative failure rates for these procedures remain significant. Migration and micromotion of the implant are the primary indicators of its postoperative stability and many in vitro measurement techniques have been discussed. However, effective, practical methods to measure these metrics in vivo have proven elusive and the evolution of such a technique is the subject of this thesis. An implantable, remotely interrogated electronic system for the in vivo measurement of both micromotion and migration in the axial direction is proposed. The main purpose of the device is to improve the ability of clinicians to assess the longterm stability of orthopaedic implants and also to plan and optimise patients’ rehabilitation protocols. The system is based on a modified form of differential variable reluctance transducer (DVRT) in which the nullpoint of the system set automatically by means of a selfcalibration process. Simulations and preliminary in vitro measurements on the bench show that the selfcalibration algorithm works correctly in spite of component tolerances and initial set up errors, allowing a gross displacement (migration) to be measured with a resolution of 15 �m and a range from 0 to 4 mm, and that the device can measure micromotion with an amplitude as low as 1 �m in the range from 200 �m to 200 �m. Accuracy of less than 10 % are achieved in both micromotion and migration measurements. Prototypes of all the major components and subsystems have been fabricated in CMOS integrated circuit (IC) technology as part of the project. Measurements support the feasibility of constructing an integrated version of the complete system for implantation and in vivo use in the future.

An important step in data processing from terrestrial laser scanning (TLS) is georeferencing, i.e. transformation of the scanner data (point clouds) into a real world coordinate system, which is important for their integration with other geospatial data. An efficient approach for this is direct georeferencing, whereby the position and orientation of the scanner can be determined in the field, similarly to the working routine of total stations. Thus the efficiency of the survey can be increased, and the project time and costs reduced. An important factor that affects the results of TLS surveys, especially those with direct georeferencing, is scanner calibration. In the recent years, the method of self-calibration used in photogrammetry has become popular for the recovery of systematic errors in laser scanners. This thesis has two main aims. The first one is to develop an approach for self-calibration of terrestrial laser scanners, which can be made available to users, and apply it to the calibration of a number of pulsed laser scanners in order to get a better insight into the systematic instrumental errors present in these instruments. The second aim is to investigate the possibilities for direct georeferencing in TLS in static applications, with the focus on the use of GPS for this purpose, and to develop a survey system based on the combination of TLS and GPS. An additional aim of the thesis is to make a systematic description of the error sources in TLS surveys, where direct georeferencing is employed. A good understanding of these error sources is necessary to secure the data accuracy. We subdivide these errors into four groups: instrumental, object-related, environmental and georeferencing. We have developed a unified approach for self-calibration of terrestrial laser scanners, where one can introduce stochastic information about all the estimated parameters, which helps in reducing their correlations. In part, it is possible to use direct georeferencing to determine the exterior orientation parameters of the scanner. We applied this approach to the self-calibration of the pulsed scanners Callidus CP 3200, Leica HDS 3000 and Leica Scan Station. The initial assumption was that the scanner systematic instrumental errors, or calibration parameters, were similar to those in a total station. However, other errors not explained by the “a priori” total station error model can be present in the scanners. We revealed two such errors – the scale errors in the vertical angles and horizontal directions in the scanners Callidus CP 3200 and Leica HDS 3000, respectively. Most systematic errors were estimated with relatively high precision and low correlations with other system parameters. We have developed a prototype combined survey system, which allows the user to use GPS for direct georeferencing of the scanner parallel to the scanning. In the current implementation, the system consists of the scanning system Leica Scan Station 2, 2 GPS receivers and antennas from Leica and a number of necessary accessories. The scanner position can be determined from RTK (or possibly Network-RTK) measurements with the accuracy of better than 1 cm, both in plane and height. The position of the backsight target can be determined from post-processing of static GPS measurements with similar accuracy. In order to estimate the accuracy of the combined system and its efficiency in a typical TLS survey, we carried out several test measurements. The results have shown that it is possible to achieve the coordinate accuracy of better than 1 cm at the object distance of up to 50 m. This is comparable to the accuracy of conventional direct georeferencing, i.e. when the scanner is centred over a known point. The time expenses for the test survey of a building located at KTH campus, starting from the planning and finishing with the georeferenced point cloud, were about 1.5 workdays. The time expenses could be reduced further if the system was installed on a moving platform during the fieldwork. Hence, the combined system can be successfully used for the surveys of built environments, e.g. engineering constructions and historical monuments, which can be carried out fast and with high accuracy. / QC 20100806 / 3D laser scanning of engineering constructions and historical monuments