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tunability
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Numerical Simulation, Tunability and Experimental Investigation of Random Lasers and Using ZnO Nanosheets in these Lasers and UV Photodetectors
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Bahrampour, Ali Reza (Supervisor) ; Taghavinia, Nima (Co-Advisor)
Abstract
In this thesis, first, random lasing in a three dimensional disordered medium has been simulated using FDTD method and some properties of random lasers which were observed by others in the previous experiments have theoretically been shown. Our simulation results show that when the density of particles increases to an upper limit, the intensity of lasing modes is enhanced. Also, the effects of pumping rate and particle size on the number of lasing modes and their intensity are studied. Lasing threshold of laser modes in different disordered systems is calculated and it is shown that by an appropriate selection of the central frequency of gain line-shape, the output power intensity of random...
Design and Implementation of Tunable Microwave Gain Equalizer
,
M.Sc. Thesis
Sharif University of Technology
;
Banai, Ali
(Supervisor)
Abstract
Modern broadband microwave and millimeter-wave systems often struggle with excessive pass band ripple and negative gain slopes due to the loss of transmission lines such as coaxial cables, or ripples in the gain characteristic of broadband amplifiers. The common solution for this problem is using a gain equalizer to compensate for the intrinsic pass band variation with some extra loss in the band of interest in return.Designed equalizers often have a constant slope in their bandwidth. However, having ripples in pass band or in other words slope changing in some parts of the band is one of the issues that designers should deal with. In this thesis, after reviewing the previous works on the...
Design and Development of Low Noise Active Inductors and a Novel General Theory for Low Phase Noise Oscillators in RF Receivers
, Ph.D. Dissertation Sharif University of Technology ; Sharif Bakhtiar, Mehrdad (Supervisor)
Abstract
In this thesis, we intend to explore the application of active inductors in high-performance radio receivers. The proposed active inductor uses a feed-forward path to improve the noise performance. This is done without sacrificing the quality factor and the power consumption. The proposed active inductor is designed and implemented in a standard 0.18μm CMOS technology. The measurement results show an almost three fold improvement in the noise performance, comparing to the typical existing structures. The resonance frequency of the inductor can be tuned from 1.8 GHz to 5.5 GHz, while the quality factor can be adjusted up to 30. The total current consumption of the active inductor is 4.8...