Novel frequency synthesizer for spur level reduction

, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 76-81 ; 9781728115085 (ISBN) Choopani, A ; Ghajari, S ; Safarian, A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

A novel frequency synthesizer architecture for reducing spur level is presented. By using a feedforward path a new zero in the transfer function is generated which enables us to increase the capacitor tied to the control voltage line and thus reducing spur level. A fast settling technique is also used to compensate the effect of spur reduction technique on settling time. Different blocks of frequency synthesizer are implemented in MATLAB/Simulink. Simulations show 13 dB improvement in reference spur level compared to conventional architecture for a 2.4 GHz frequency synthesizer

5-6 GHz dual-vector phase shifter in 0.18 μm LID CMOS

, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 82-86 ; 9781728115085 (ISBN) Choopani, A ; Fakharzadeh, M ; Safarian, A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2019

Abstract

In this paper, a low power active phase shifter in 0.18 μm CMOS technology, operating from 5 to 6 GHz, for WLAN applications is presented. Design equations for this novel structure, which consists of two current steering stages, transconductance stage and DACs, are derived, thoroughly. This phase shifter has a range of 360° with 5.625° phase resolution. The power consumption is 35 mW. The RMS phase error is only 0.3°. The simulated power gain, input P1dB, and NF are 4 dB, -0.8 dBm and 6 dB, respectively

Optimization of Heat Recovery and Water Capture System from Boiler Flue Gas

, M.Sc. Thesis Sharif University of Technology Armin, Bahman (Author) ; Saboohi, Yadollah (Supervisor)

Abstract

Thermal energy and water in flue gases varies with the type of fuel and thermal conversion system. Flue gas temperature is maintained in the range of 140 (℃) to 200 (℃) and it is subject to the sulfur content of the fuel. Vapor content of the flue gas is in the range of 10%_20% of volumetric flow. Considerable part of vapor may be recovered which can be used as cooling water make up. There are various means and methods for water capture and heat recovery which includes shell-tube heat exchanger among others. Selection of appropriate material and heat exchanger is conditioned by corrosion, temperature of flue gas and it’s economic feasibility. Identification of an optimal design of...

Design and Manufacturing of a Multi Functional Device For Experimental Fatigue Test and Special Facilities for Symmetric and Anti Symmetric Loading on Gears

, M.Sc. Thesis Sharif University of Technology Armin, Amir (Author) ; Durali, Mohammad (Supervisor)

Abstract

The goal of this research is design and manufacturing of a device for fatigue test and 3D crack propagation in spur gear roots. Clearly it should be able to test gear in oscillated bending load and control the amplitude and period of loading. Designed setup in this project using a electro hydraulic actuator can do it up to 50 KN and 10 Hz in amplitude and frequency and a PLC controls it during the test time. System can load gears symmetric or anti symmetric and simulate the effect of shaft misalignments, bearing damage and gear production tolerances on the gear loading. System completely designed, built and tested during this project and using experimental data, its performance was...

Design of Low Spur Fast Settling Integer-N Frequency Synthesizer for Bluetooth Application

, M.Sc. Thesis Sharif University of Technology Choopani, Armin (Author) ; Safarian, Amin Ghasem (Supervisor) ; Atarodi, Mojtaba (Supervisor)

Abstract

Frequency synthesizers are one of the most critical building blocks of RF systems. Their task is to produce high-frequency precise and stable clock signals from a low-frequency source. The signal used in mixers to up-convert and down-convert desired signals in transceivers and the precise clock of analog to digital converters are made by frequency synthesizers. Designing frequency synthesizer, because of its lots of parameter and dependency of these parameters to each other, is a hard task which forces designers to propose new structures. In this thesis, an integer-N frequency synthesizer for Bluetooth application, with the goals of decreasing spurious tones power and settling time, is...

Wake interference of two identical oscillating cylinders in tandem: An experimental study

, Article Ocean Engineering ; Volume 166 , 2018 , Pages 311-323 ; 00298018 (ISSN) Armin, M ; Khorasanchi, M ; Day, S ; Sharif University of Technology

Elsevier Ltd 2018

Abstract

This study aims to assess the impact of the spacing between cylinders on their dynamic behaviour. Observations during this experiment have helped to identify the effect of spacing on excitation mechanism of each cylinder as well as establishing the relationship between cylinders response and the spacing between them. Arrays of cylindrical Structures in close proximity are common in variety of engineering structures, particularly in the offshore industry. If the cylinders are flexible, and are subject to excitation from fluid flow, then the dynamics is influenced by complex interactions between the cylinders, dependent on a variety of parameters. Two cylinders were flexibly mounted in tandem...

On the development of a nonlinear time-domain numerical method for describing vortex-induced vibration and wake interference of two cylinders using experimental results

, Article Nonlinear Dynamics ; 2021 ; 0924090X (ISSN) Armin, M ; Day, S ; Karimirad, M ; Khorasanchi, M ; Sharif University of Technology

Springer Science and Business Media B.V 2021

Abstract

A nonlinear mathematical model is developed in the time domain to simulate the behaviour of two identical flexibly mounted cylinders in tandem while undergoing vortex-induced vibration (VIV). Subsequently, the model is validated and modified against experimental results. Placing an array of bluff bodies in proximity frequently happens in different engineering fields. Chimney stacks, power transmission lines and oil production risers are few engineering structures that may be impacted by VIV. The coinciding of the vibration frequency with the structure natural frequency could have destructive consequences. The main objective of this study is to provide a symplectic and reliable model capable...

A Semi-Supervised Algorithms for Clustering Microarray Data

, M.Sc. Thesis Sharif University of Technology Eslamzadeh, Habibollah (Author) ; Mahdavi Amiri, Nezamoddin (Supervisor) ; Madadkar Sobhani, Armin (Supervisor)

Abstract

Microarray which is also known as Biochip is a flat substrate of glass with the size of 1 ×1 cm on which a numerous number of biosensors are placed in an array format. Microarray DNAs are used to measure expression level of thousands of genes. Repeating these experiments in different conditions can result in patterns of expression. After preparation, the florescent sample is hybridized with the sensors of microarray surface and fluoresce intensities of the spots are measured by a special camera called CCD. The obtained pictures are examined by a computer and the spot lights converted into numerical data by image processing algorithms. Putting these numbers into matrices of size m×n is...