Sharif Digital Repository

Growing demand for increased data transmission in communication systems and the internet, has intensified the need to increase the bandwidth of high speed transceivers. One of the main elements in high speed receivers is the clock and data recovery circuit which guarantees the transfer of data with high reliability. In this thesis, the design of a clock and data recovery circuit for high frequency applications is considered. The aim of this project is the design of a circuit with low power and low jitter for high-speed input data. A new four stage LC ring oscillator is designed that works at the quarter rate of the input. A new idea for the design of the binary phase detectors has also been... 

Some applications need fast locking clock and data recovery circuits for example the circuits that operate in burst mode must lock to the data packets which are transmitting from different transmitters very quickly and in just a few bit times. In such applications open-loop clock and data recovery circuits are used because lock time in closed-loop clock and data recovery circuits is usually much longer.
In this thesis a new open loop clock and data recovery circuit based on injection locking method has been proposed. This circuit can be used in applications such as passive optical networks that need fast locking. In this architecture a super harmonic injection-locked frequency divider... 

Analog to digital converters are one of the most important component of Bluetooth and GSM receivers. The pipeline and Successive Approximation Register (SAR) ADCs are mainly used in these receivers. However, the pipeline ADCs consume lots of power and SAR ADCs suffer the resolution in advanced technologies. On the other hand, the Delta-Sigma ADCs are capable of achieving high resolution with a low power. So in this thesis, the various kinds and different implementations of Delta-Sigma Modulators are introduced. The system level design and the conversion between Discrete-Time Modulators and Continuous-Time Modulators are explained. The non-ideality effects such as limited gain and bandwidth... 

SAR image noise is a significant problem for SAR image analysis.The inherent noise of SAR images, known as speckle, seriously affects the SAR image interpretation. It also has adverse effects on the classification and segmentation of SAR images. Due to its great significance, the SAR image processing has received considerable attention in recent years and many researchers have developed techniques to reduce the inherent noise accompanying the SAR images. A survey of the literature shows that the wavelet analysis is one of the most common methods used for speckle reduction. While the power of the morphological analysis method has mostly not been recognized, we have utilized this efficient... 

Polypropylene plants receive propylene monomer and produce polypropylene polymer by inducing chemical reactions under high pressure and high temperature conditions. In these plants it is essential to monitor and carefully control the density and level of the material contents in slurry high pressure and high temperature reactors and vessels. Due to process conditions and the advantages of the non contact measuring method we use radioactive level and density measurement method specially gamma ray level and density detectors and transmitters in P.P plants. Sometimes, however known and unknown natural or manmade factors may affect the performance of these devices. The known factors such as NORM... 

Effect of resolution of Time to Digital Converters (TDCs) on the performance of All-Digital Phase Locked Loops (ADPLLs) and capability of achieving higher resolution in advanced technologies lead to introducing different kinds of TDCs. Beside the analysis of different kinds of TDCs, This thesis proposes three new TDCs based on the time amplifi-cation concept. A new pipeline TDC is designed using a wide dynamic range time amplifi-er. A new method is used to widen dynamic range of the conventional time amplifiers. In order to get a low power high resolution conversion, a new delay element design is devel-oped to reduce the delay value and its sensitivity to mismatch and process variations.... 

Many applications that require heavy processing, such as augmented reality, facial recognition, self-driving cars, and digital healthcare systems, are emerging. Many devices in the Internet of Things space cannot process such a volume of calculations. One of the newest methods to solve this problem is using new architectures in network design, among which we can refer to the edge computing architecture. In this method, by offloading the computation on the available computing resources close to the network's end nodes, we try to provide the results of the calculations for the end nodes of the network as quickly as possible. In this thesis, the problem of determining the computation offloading... 

In this thesis, we study the task of sign language translation using a non-end-to-end framework by utilizing large language models. The proposed method initially generates a sequence of glosses corresponding to a sign language video through a continuous sign language recognition model, which is then considered as input for a language model. The role of a language model in this framework is to translate the sequence of glosses into coherent sentences in spoken language. Given the limited training resources available for machine translation models on the specific problem of sign language to text translation, leveraging large language models can be highly beneficial due to the accumulated... 

In this research non-contact ultrasonic based method is used for liquid level measurement in a container. A system has been designed and developed to determine the liquid level and show the results on a personal computer. The system contains three main parts, which are mechanical and electronic parts and the programming. The setup can measure the liquid level with the accuracy of 1cm. An ATMEGA8 microprocessor commands to relays and controls the pumps. The pumps are used to change the height of the liquid in the containers to accurately calibrate the sensor and test its operation. The ultrasonic sensor, which is mounted above the vessel, transfers the data to an ATMEGA64 microprocessor for... 

High speed data converters are very often used in telecommunication systems. Since these systems are increasingly used in mobile form reducing the power consumption in these circuits is of great importance. The goal of this project was to design a pipeline 10 bit converter for a sample rate of 500 M sample/s with a power consumption of 50mW for the input level of 1Vp-p and a 1.5V power supply in 0.18μm CMOS technology. To reach these goals a number of low-power techniques are proposed in various levels of abstraction. In system level, the sampling and feedback capacitors, as well as the stage resolution of the ADC is optimized .And to... 

The purpose of this thesis is designing and implementation of a Carry Skip Adder using CMOS traditional technology and Gate Diffusion Input technique (GDI). I present a carry skip adder (CSKA) structure that has a higher speed, lower energy consumption compared with the conventional one. The Gate Diffusion Input is a novel technique for low power digital circuit design. This technique reduces the power dissipation, propagation delay, area of digital circuits and it maintains low complexity of logic design  

The rapid development of scientific areas in this modern era makes the process of finding new field of research slow and laborious for prospective scholars. Thus, having a vision of the future could be helpful to pick a right path for doing researches and ensuring that it is worth to invest in. This thesis seeks to predict research trends by using link prediction approaches on keywords network and discusses about the performance of various algorithms in different situations. Moreover, for the last part of the experiments, novel link prediction algorithms are proposed by the author, enhances the accuracy of prediction results. The data set collected from Sciencedirect and Scopus by a strong... 

When the keywords in academic articles are collected and accumulated to achieve a certain amount, they will display a network property. This property can help us to get the hotspot graph of science by using the keywords network, which is directly related to the subject of the paper. Also by analyzing this network, it is possible to forecast the future science hotspots.By analyzing keywords network from complex networks point of view, we are able to predict the future hotspots based on current trends, previous growth patterns that happened or with the power of different centrality measures like eigenvector etc. As an example, when a new keyword appears in a paper for the first time, a complex... 

The use of the Internet of Things in buildings has become increasingly important. Meanwhile, sensors and actuators play a very important role. With the help of sensors, various data of residents' environment and behavior can be obtained and various parameters can be controlled through actuators. Data from the presence, measurement and decision making of the components of this structure in a building can be used to model and predict the behavior of residents with methods of machine learning, data mining and artificial intelligence such as deep learning and Gaussian processes, helping to achieve the goal of residents' comfort and energy saving.In the desired structure, the sensor- actuator... 

Nowadays, by integrating the Internet of Things systems into the daily life of humans, mankind has created a platform for providing numerous and diverse services through which life has become much simpler and more convenient. These systems have gradually become an integral part of today's life. They are used in many areas of production and service provision, such as healthcare, agricultural industry, supply chain, education system, transportation, and many others. Although these achievements have facilitated human life in many aspects, they are also associated with many security risks. Intrusion detection systems (IDS) are methods for predicting possible damage (through security attacks such... 

In this thesis, A novel approach for ¼-rate clock Phase Detector (PD) structure for Phase Locked Loop (PLL)-based Clock and Data Recovery (CDR) is proposed. In this approach, the retimed data is generated within the circuit and no extra circuit is needed. Another advantage of this topology is that the error and reference signals are independent of delay time through gates and no extra replica circuit is needed to compensate the delay. This topology results in a lower power circuit and smaller area for high speed application compared to conventional topologies  

Embedded SRAM unit is recognized as an important block in the systems on chip. In recent years due to an abrupt increase in the number of such systems which often work with battery, the priority of designing of low power circuits has been increased. Furthermore, increase in the number of transistors in the SRAM and increase in leakage current of MOS transistors with technology scaling have rendered the SRAM into the main energy consumer (from both static and dynamic view).In the writing operation due to the full swing of bit line, the dynamic power forms the main chunk of the consumptive power. The static consumptive power mostly happens due to the leakage current of broken cells in an array...