Sharif Digital Repository

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... 

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... 

In recent years, communication systems with multiple antennas at the transmitter side and multiple antennas at the receiver side, shortly known as MIMO systems, have attracted a lot of attentions. Capability of these systems to increase the bandwidth efficiency and capacity of communication links has made them the core technology of next generation wireless systems.
As a first step to design and evaluate the performance of a MIMO system, a suitable channel model which is able to reflect the physical characteristics of the real environment appropriately is essential. Recently, a lot of models have been suggested to investigate MIMO channels, especially correlative models which use... 

Today’s radio transmitters must be able to send information in several standards. One problem involved in these wide band electronic systems lies in its end part, ie power amplifier. To have a broad band width either switching must be made among several power amplifiers with narrow band width (tuned) or the transistor part of power amplifier must be the same and single and selection be made only among matching networks. In this thesis, a power amplifier with broad band width without requiring a matching network has been designed and laid out. Also considering the low breakdown voltage of the gate oxide of the today’s standard CMOS transistors, it is very difficult to get a high output power... 

In this research, the design of a broadband multi-phase frequency synthesizer, applicable for the multi-path structure in the 5G NR1 transmitter, is investigated. This standard presents new challenges for synthesizer design; The synthesizer in such a system must cover a wide frequency range. On the other hand, since this standard employs Orthogonal Frequency Division Multiplexing, it must meet the stringent requirement of integrated phase noise over multiple decades of frequency. The synthesizer employs the phase-locked loop architecture. The frequency division method has been used to construct eight symmetrical phases. The designed synthesizer can generate a frequency range of 600 MHz to 5... 

tIncreasing the bandwidth of a receiver is limited to the bandwidth of the system's internal components such as amplifiers, power dividers / combiners, and directional couplers, which are widely used in array antenna systems. Wilkinson splitters are often used for balanced power dividers and hybrid branch line couplers are used for directional couplers because their macrostrip structure makes them lighter and cheaper, and ultimately increases their use. Unfortunately, these elements provide up to 20% fractional bandwidth, which is not enough in our intended use. Also, the design of the power divider at millimeter wave frequencies has challenges such as matching impedance across all bands and... 

In this thesis, a wideband multi-standard digital transmitter based on the multi-path architecture has been designed in 65-nm CMOS process. Moreover, the effect of phase error of the clocks on the output specifications of this multi-path transmitter has been analyzed, and based on the derived theoretical equations, circuit-level solutions for the correction of these errors have been proposed. In addition to the circuit-level solutions for error correction of the clocks, a general setup for calibration of the multi-path transmitter has been presented. Also, several software-based algorithms for the calibration of the transmitter have been studied and their validity has been verified using...