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    Locked and unlocked behaviour of mutually coupled microwave oscillators

    , Article IEE Proceedings: Microwaves, Antennas and Propagation, Stevenage, United Kingdom ; Volume 147, Issue 1 , 2000 , Pages 13-18 ; 13502417 (ISSN) Banai, A ; Farzaneh, F ; Sharif University of Technology
    IEE  2000
    The interinjection locking of microwave oscillators is investigated using differential equations governing the locking behaviour of two mutually coupled oscillators. The behaviour of the oscillators before and after locking is described, and the common oscillation frequencies, locking range and transient time constant are calculated. The spectra of the oscillators in the unlocked condition are also investigated, with particular attention to the spacing and amplitude variation of the spectral lines. Experimental results in connection with the theoretical investigations are also presented  

    Design & Implementation of Test circuit for an array of sensor Diodes in Low Temperature (77K)

    , M.Sc. Thesis Sharif University of Technology Ghoreishizadeh, Sara (Author) ; Medi, Ali (Supervisor) ; Fardmanesh, Mahdi (Supervisor)
    A Focal Plane Array (FPA) consists of one or two dimensional array of sensor elements and is widely used in imaging systems. Generally an FPA can be divided into two main parts: Sensor array and read-out/test circuit. In this thesis we design and implement a test circuit for an FPA that works in 77K. The circuit will be attached to the sensor to detect and amplify its very low level current that is in the range of 10 pA to more than 10 nA. Reducing MOSFET temperature from room temperature (300K) down to liquid nitrogen (77K) will greatly changes its parameters and characteristics such as Threshold Voltage and carrier mobility. However MOSFET models in low temperature are either... 

    Investigation of Temperature Effect on MOSFET Parameters and Modeling of Carrier Mobility in Temperature Range of 77 - 300K

    , M.Sc. Thesis Sharif University of Technology Seyed Fakhari, Moein (Author) ; Fardmanesh, Mahdi (Supervisor) ; Medi, Ali (Supervisor)
    Temperature reduction from room temperature to liquid nitrogen temperature has a significant effect in improvement of semiconductor devices operation such as field effect transistors. Nowadays cryoelectronics as a considerable branch of electronics is concerned by several groups. In order to optimize the procedure of low temperature IC design and fabrication we investigated the temperature effects on different parameters of MOSFET in this thesis. Several transistors in a variety of channel lengths were fabricated in different technology files. Wide measurement experiments were done on these transistors in order to find their drain current vs. drain to source voltage characteristics. From... 

    FDTD analysis of distributed amplifiers based on the fully distributed model

    , Article 2007 Asia-Pacific Conference on Applied Electromagnetics, APACE2007, Melaka, 4 December 2007 through 6 December 2007 ; 2007 ; 1424414350 (ISBN); 9781424414352 (ISBN) Mirzavand, R ; Abdipour, A ; Shishegar, A. A ; Sharif University of Technology
    In this paper a wave approach has been introduced to study the performance of a distributed amplifier. The time domain response of a FET is obtained by means of the fully distributed model. By applying the procedure to a pi-gate GaAs MESFET, the S matrix is computed from time domain results over a frequency range of 2-20 GHz. Scattering parameters of gate and drain lines are extracted from three-dimensional FDTD simulation. The result obtained by this wave approach is compared with device lumped model and Quasi static approach of transmission line. © 2007 IEEE  

    Design of a Low Power and Robust SRAM Cell Based on FinFET

    , M.Sc. Thesis Sharif University of Technology Sayyah Ensan, Sina (Author) ; Hesabi, Shahin (Supervisor) ; Moaiyeri, Mohammad Hossein (Supervisor)
    By scaling the technology node, leakage power and process variations emerge as the two important factors to design a chip. Static power becomes more important when the number of portable devices which spend most of the time in the idle mode is increasing.Process variations lessen performance, reliability and lead to more leakage power. To mitigate these limitations multiple devices have been proposed to displace Bulk MOSFET.Among these devices we can name FinFET and CNTFET transistors. FinFET transistors due to their superior gate control in compare to Bulk MOSFETs transistor have shown lesser short channel effects, more scalability, more I_on to I_off ratio and lesser process variations.... 

    Design of DC-DC Buck Converter Based on Reliability Considerations

    , M.Sc. Thesis Sharif University of Technology Javadian Jazy, Vahid (Author) ; Kaboli, Shahriyar (Supervisor)
    Nowadays power electronic devices have a wide usage in the industries for power conditioning. As a point of view, reliability is one of the most important figure of merits that should be considered to have long life time and also have more probability to do exactly the proposed mission. One of the widely used converter topologies is DC-DC step down converter which is used in different applications such as battery charger and voltage regulator. In this project, a step down DC-DC converter with Buck topology is designed with reliability consideration. Failure rate of power components are predicted based on MIL-HDBK-217. In addition, failure rate of auxiliary components of power devices are... 

    Theory and Simulation of Nonlinear Transmission Lines Using MOSFET Devices

    , M.Sc. Thesis Sharif University of Technology Kalantar Hojjatabadi, Mohsen (Author) ; Farzaneh, Forouhar (Supervisor)
    Nonlinear transmission line (NLTL) a guiding structure contains nonlinear elements. For discrete NLTLs, this structure is periodically loaded with nonlinear elements. In the structure of this line nonlinear elements such as ceramic capacitors, nonlinear magnetic elements, vector diodes, Mos transistors, etc can be used. With the rapid development of semiconductor devices and microwave band systems, the demand for implementation of NLTLs has increased. These lines provide wide band-width, cut-off frequencies over the hundreds of GHz and picosecond rise time for various systems.Among the applications of NLTL, the generation of high power RF pulses has attracted the most attention. In this... 

    Analysis of the Challenges in the Design of High Power and High Frequency Inverters

    , M.Sc. Thesis Sharif University of Technology Amerian, Pourya (Author) ; Kaboli, Shahryar (Supervisor)
    Power Inverter or DC to AC voltage converter is one of the most important and widely discussed topics in the world of power electronics and systems such as DC/DC converters. Increasing the switching frequency of the inverter, in addition to its many advantages, also creates challenges that will be addressed in this dissertation. To build a high frequency yet reliable inverter, you need accurate and comprehensive information about the inverter circuitry, parasitic elements, switches and their behavior against fault conditions such as short circuit, protection requirements and etc.In this dissertation, several MOSFET transistors is shorted under various test conditions while parameters...