Sharif Digital Repository

Emergence of the implantable biomedical microsystems and personal area networks in recent years result in a new class of biomedical systems that requires data transmition in short range at various data rates. Performing with ultra low power consumption and long battery life are crucial in these systems. Therefore, designing low power radios for these systems is still an active research area. Ultera wideband systems are specially considered for implementations because of their potential characteristics.
In this dissertation, different biomedical applications and data communication approaches are surveyed. Then, Different architectures of UWB receivers are reviewed. To implement a low... 

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 40 M sample/s with a power consumption of 20mW for the input level of 1Vp-p and a 1V power supply in 0.13μm 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 analytically which leads to simple back-envelope formulas to... 

Considering the drastical increasing of greenhouse gases in the atmosphere, especially carbon dioxide, reduction of these gases seems necessary to combat global warming. Fossil fuel power plants are one of the main sources of CO2 emission. In this thesis, CO2 capture from a natural gas fired combined cycle power plant using different oxygen percent in air feed is studied. Aspen Plus was used to evaluate the effect of this capture technology on the plant efficiency and energetic parameters of the system. Aspen Hysys is used to simulate Amine absorption tower and Air Separation cryogenic tower. Since the oxygen production plant, CO2 capture and transport are cost and energy intensive, the cost... 

With the rapid development of wireless communication standards, the co-existence of multiple standards in a single chip becomes inevitable. It is also fueling interest in analog to digital converters (ADCs) that are reconfigurable over a wide range of bandwidths and resolutions with adaptive power consumption. Employing such ADCs rather than using multiple individually power-optimized ADCs results in a great reduction of silicon area. Hence, a reconfigurable ADC can reduce time to market, and save costs.
This thesis addresses the challenges exists in conventional reconfigurable methods, and presents a novel reconfiguration methodology for changing resolution in pipeline ADCs. The... 

iN This thesis, Design and implementation of a low voltage, low power Delta-Sigma Modulator (DSM) is presented. System level considerations have been discussed thoroughly. In addition a systematic design flow in the context of continuous time delta sigma modulators is provided. While voltage-domain signal processing becomes more difficult in deep sub-micron processes, a finer time resolution is achievable. Time-domain quantizers can ameliorate the design challenges of flash quantizers which arises from lower supply voltages and higher fraction of comparator metastable region. VCO based quantizer such as voltage to frequency and voltage to phase considered as time domain quantizers can be a... 

Nowadays embedded system play an important role in human life. The majority of these systems work in harsh environments which intensifies the importance of fault tolerance in embedded systems. This capability is usually achieved by adding redundancy to the system. But common embedded systems are weaker than desktop and server systems and probably have a limited source of power which makes the redundancies expensive. Hardware fault tolerant techniques impose significant cost to system and increase the development time which makes software-only solutions more attractive. An important general purpose software-only technique in protecting the application data is EDDI. This technique is based on... 

Gain bandwidth products of Operational Amplifiers are dependent to power consumption. In this thesis we introduce negative capacitance circuit as a candidate to improve GBWs of OPAMPs in constant power, or achieve the requested GBW in lower power consumption. First we characterize negative capacitance circuit and introduce a model for that. Then we see how pole-zero placement will change, when we add negative capacitance circuit to a circuit node. As an application we use this circuit in Folded Cascode and Current mirror OPAMPs and give design guideline for this topologies. A three stages and a one stage OPAMP is designed in 0.18um CMOS, for the application of negative capacitance... 

High speed data converter are very often used in telecommunication systems. Since these systems are increasingly used in mobile foem 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 200MS/s with a power consumption of 35 mW for the input level of 1Vp-p and a 1.8V power supply in 0.18um CMOS technology.
To reach these goals, a number of low power techniqes are proposed in various levels of abstraction. In system level, the sampling and feedback capacitors is optimized analytically which leads to simple back-envelope formulas to calculate the optimum values. In circuit level, a... 

SAR ADC is a data converter which is based on binary search to convert an analog signal to a digital signal. Unlike other converters like pipeline, most of its constituent parts are digital, and hence scalable with process and consume less power, moreover can have better speed and power performance. With advanced technologies, namely 45nm and 32 nm CMOS, SAR ADCs are preferable as they consume much less power and area, therefore well-suited for portable applications, as opposed to Flash and Pipleline converters.
The main drawback of this type of converter is its limited speed which is due to the fact that one clock cycle is required to evaluate each bit. As a result, there is a... 

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.... 

The telecommunication manhole is a place that the cables of the telephone network are located on it. line Inside these manholes, there are equipment and cables for telephone. The number of these places is many, so protection and maintenance of the manholes have been problematic in case of theft of the cap, equipment inside them and flooding. Also, lack of inspection officers and the high cost of repairing and replacing parts inside them, has made it difficult for telecom companies to handle these problems. The only way to connect the manhole is a telephone line inside them. Also, there is no proper electrical power inside the manhole, so the design and implementation of a system that... 

During recent years the main concern of analog designers is to get the most use of Computer Aided Design (CAD) tools for design procedures.Thus the main purpose of this thesis is to introduce a very fast and precise CAD tool for the design of pipelined analog to digital converters (ADC). This is accomplished by utilizing some simulation and optimization based CAD tools at the same time. In the optimization part, the conventional numerical methods are replaced with the proposed analytical approaches. Also, anew algorithm is used in the simulation part, which makes the monte-carlo simulation to be faster compared to the conventional cases. To verify the accuracy of CAD tool performance, a...