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Performance limits of optical clock recovery systems based on two-photon absorption receiver structure [electronic resource]
, Article IEEE Journal of Selected Topics in Quantum Electronics ; Vol.14, No.3, PP. 963-971 May/June 2008 ; Salehi, J. A ; Sharif University Of Technology
Abstract
In this paper, we analyze and discuss the performance limits of optical clock recovery systems using a phase-locked loop (PLL) structure with nonlinear two-photon absorption (TPA) phase detection scheme. The motivation in analyzing the aforementioned optical PLL with TPA receiver structure is due to a recent successful experiment reported in . We characterize the mathematical structure of PLLs with TPA, so as to evaluate the performance limits on optical clock recovery mechanism. More specifically, we identify two intrinsic sources of phase noise in the system namely, the on- off nature of the incoming data pulses and the detector's shot noise that ultimately limit the performance of the...
Design of a DLL-Based Frequency Synthesizer for Wireless Recievers
,
M.Sc. Thesis
Sharif University of Technology
;
Sharif Khani, Mohammad
(Supervisor)
;
Atarodi, Mojtaba
(Supervisor)
Abstract
A DLL-based frequency synthesizer that has the capability of producing fractional multiples of the reference frequency is designed and implemented in this thesis. The new structures for producing fractional multiples of reference frequency with DLLs are also presented. The designed frequency synthesizer is not a Sigma-delta modulator for synthesizing. This structure has a low jitter and phase-noise, low chip area, low settling time and a good stability due to its DLL-based nature. Also, a systematic model for simulating DLLs in MATLAB Simulink is proposed that is very efficient for giving a better insight to designing of DLLs. The settling time of the proposed topology for DLL is 2.5us. The...
A novel design of hybrid-time-interleaved current steering digital to analog converter and its behavioral simulation considering non-ideal effects
, Article Integration ; Volume 69 , 2019 , Pages 321-334 ; 01679260 (ISSN) ; Torkzadeh, P ; Sadughi, S ; Sharif University of Technology
Elsevier B.V
2019
Abstract
This work presents a behavioral model for non-ideal effects in a novel Hybrid time-interleaved digital to analog converter (TIDAC). In Hybrid DACs, both ΔΣ and Nyquist structures are used. In this work, in the Nyquist path, the 2-time-interleaving technique is used and in the ΔΣ path, a new structure is proposed to reduce the critical path in the TI delta-sigma modulator (DSM). In conventional TIDSM, adding each channel to the structure leads to increasing the critical path as one full-adder. This, in turn, decreases the speed of modulator since a single feedback loop is utilized to compute the running sum of the input signals. In this work, a new type of poly-phase decomposition is...
Jitter-buffer management for VoIP over wireless LAN in a limited resource device
, Article 4th International Conference on Networking and Services, ICNS 2008, Gosier, 16 March 2008 through 21 March 2008 ; 2008 , Pages 90-95 ; 076953094X (ISBN); 9780769530949 (ISBN) ; Tabandeh, M ; Behboodi, A ; Fotowat Ahmadi, A ; Sharif University of Technology
2008
Abstract
VoIP over WLAN is a promising technology as a powerful replacement for current local wireless telephony systems. Packet timing Jitter is a constant issue in QoS of IEEE802.11 networks and exploiting an optimum jitter handling algorithm is an essential part of any VoIP over WLAN (VoWiFi) devices especially for the low cost devices with limited resources. In this paper two common algorithms using buffer as a method for Jitter handling are analyzed with relation to different traffic patterns. The effect of different buffer sizes on the quality of voice will be assessed for these patterns. Various traffic patterns were generated using OPNET and Quality of output voice was evaluated based on ITU...
Low power Clock and Data Recovery Circuits in 20Gb/s Range in CMOS Technology
, M.Sc. Thesis Sharif University of Technology ; Hajsadeghi, Khosrow (Supervisor)
Abstract
Growing demand for increased data transmission in communication systems and the internet, has intensified the need to increase the bandwidth of high speed transceivers. One of the main elements in high speed receivers is the clock and data recovery circuit which guarantees the transfer of data with high reliability. In this thesis, the design of a clock and data recovery circuit for high frequency applications is considered. The aim of this project is the design of a circuit with low power and low jitter for high-speed input data. A new four stage LC ring oscillator is designed that works at the quarter rate of the input. A new idea for the design of the binary phase detectors has also been...
Design of Clock and Data Recovery Circuits Inmulti Gb/s Range in CMOS Technology
, M.Sc. Thesis Sharif University of Technology ; HajSadeghi, Khosrow (Supervisor)
Abstract
Some applications need fast locking clock and data recovery circuits for example the circuits that operate in burst mode must lock to the data packets which are transmitting from different transmitters very quickly and in just a few bit times. In such applications open-loop clock and data recovery circuits are used because lock time in closed-loop clock and data recovery circuits is usually much longer.
In this thesis a new open loop clock and data recovery circuit based on injection locking method has been proposed. This circuit can be used in applications such as passive optical networks that need fast locking. In this architecture a super harmonic injection-locked frequency divider...
In this thesis a new open loop clock and data recovery circuit based on injection locking method has been proposed. This circuit can be used in applications such as passive optical networks that need fast locking. In this architecture a super harmonic injection-locked frequency divider...
Performance Ehancement of Congestion Control Algorithm Through Traffic Flow Istinction
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
Congestion is an important issue in the network environment. To keep stable the perfor-mance of the network, congestion control algorithms have been extensively studied. Queue management method employed by the routers is one of the important issues in the congestion control study. Active Queue Management (AQM) has been proposed for early detection of congestion inside the network. AQM mechanisms control the queue length in a router by dropping arriving packets. The Random Early Detection (RED) is the most popular AQM mechanism used in routers on the Intenet to allow network users to simultaneously achieve high throughput and low average delay. The RED algorithm may cause heavy oscillation of...
Collective dynamics of interacting particles in unsteady flows
, Article SIAM Journal on Applied Dynamical Systems ; Vol. 13, Issue. 1 , 2014 , pp. 194-209 ; ISSN: 15360040 ; Jalali, M. A ; Sharif University of Technology
Abstract
We use the Fokker-Planck equation and its moment equations to study the collective behavior of interacting particles in unsteady one-dimensional flows. Particles interact according to a longrange attractive and a short-range repulsive potential field known as Morse potential. We assume Stokesian drag force between particles and their carrier fluid and find analytic single-peaked traveling solutions for the spatial density of particles in the catastrophic phase. In steady flow conditions the streaming velocity of particles is identical to their carrier fluid, but we show that particle streaming is asynchronous with an unsteady carrier fluid. Using linear perturbation analysis, the stability...
Yield-driven design-time task scheduling techniques for multi-processor system on chips under process variation: A comparative study
, Article IET Computers and Digital Techniques ; Volume 9, Issue 4 , 2015 , Pages 221-229 ; 17518601 (ISSN) ; Assare, O ; Rahmati, N ; Boroumand, A ; Barati, S ; Goudarzi, M ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
Process variation has already emerged as a major concern in design of multi-processor system on chips (MPSoC). In recent years, there have been several attempts to bring variability awareness into the task scheduling process of embedded MPSoCs to improve performance yield. This study attempts to provide a comparative study of the current variation-aware design-time task and communication scheduling techniques that target embedded MPSoCs. To this end, the authors first use a sign-off variability modelling framework to accurately estimate the frequency distribution of MPSoC components. The task scheduling methods are then compared in terms of both the quality of the final solution and the...
Cooperative cyclostationary spectrum sensing in cognitive radios at low SNR regimes
, Article IEEE International Conference on Communications, 23 May 2010 through 27 May 2010, Cape Town ; 2010 ; 05361486 (ISSN) ; 9781424464043 (ISBN) ; Nasiri Kenari, M ; Le Ngoc, T ; Sharif University of Technology
2010
Abstract
The paper proposes efficient cooperative cyclostationary spectrum sensing schemes in which each secondary user (SU) performs single-cycle cyclostationary detection for fast and simple implementation, while collaboration between SUs in final decision on the presence or absence of the primary user (PU) is explored to improve its performance. As the SUs simultaneously measure the spectral correlation functions at different cycle frequencies (CF) and exchange their information regarding the measured results, a sufficient number of CFs are effectively examined in a short period of time because of parallel searching, which makes the proposed cooperative spectrum sensing more reliable and faster....
All-Optical Clock Recovery Using Nonlinear Kerr Effect in Optical Fibers
, M.Sc. Thesis Sharif University of Technology ; Salehi, Javad (Supervisor)
Abstract
In this thesis, a brief review of the previously introduced all optical clock recovery methods are presented and then, two novel all optical PLLs, based on nonlinear Kerr effects in fiber optics, are introduced and thoroughly investigated. To obtain more insight into the subject, firstly, nonlinear Kerr effect and its two main applications, including FOPA amplifiers and optical Kerr shutters are described. One of the proposed PLLs employs a FOPA in its error signal detection process, and the other is based on using two Kerr shutter switches to detect the error signal. Since the PLLs are based on the quasi-instantaneous Kerr effect, they are expected to be suitable in ultra-high speed...
Statistical Analysis of Optical Clock Recovery System Based on Second Harmonic Generation (SHG) Detection Scheme in Optical Networks
, M.Sc. Thesis Sharif University of Technology ; Salehi, Javad (Supervisor)
Abstract
In this thesis, we statistically model and analyze one of the main systems in optical communications which are based on Second HarmonicGeneration (SHG) process. To this end, we first introduce various applications of this process in optical communication systems and see that the main application of this nonlinear process is in the process of optical clock recovery in both of OTDM and SPE_OCDMA networks. In the rest of the thesis, we characterize the mathematical structure of these systems and use that to statistically analyze their behavior. In considering the optical clock recovery system based on SHG, we introduce three intrinsic sources of timing jitter in the system, namely, the On-Off...
Theoretical considerations in designing ultra-high speed all-optical clock recovery using fiber optical parametric amplifiers
, Article Journal of Lightwave Technology ; Vol. 32, issue. 15 , August , 2014 , pp. 2678-2689 ; ISSN: 07338724 ; Salehi, J. A ; Sharif University of Technology
Abstract
In this paper, a new all-optical phase-locked loop (OPLL) in a TDM system is proposed and analyzed. The scheme relies on using fiber optical parametric amplifier (FOPA) device models and theories. In the proposed OPLL, the local clock pulse stream and the received data signal pulses are fed into the FOPA as its pump and amplified signals, respectively. The power of the resulting, relatively, strong idler signal depends on the phase difference between the local clock and the received data signal pulses, and it is used to reveal the OPLL's error signal. We characterize the mathematical structure of the proposed OPLL and identify its three intrinsic sources of phase noises namely, randomness of...
Eye diagram parameter extraction of nano scale VLSI interconnects
, Article 2012 IEEE 21st Conference on Electrical Performance of Electronic Packaging and Systems, EPEPS 2012 ; 2012 , Pages 327-330 ; 9781467325394 (ISBN) ; Sarvari, R ; Seydolhosseini, A ; Sharif University of Technology
2012
Abstract
In this paper, jitter due to both capacitive and inductive coupling is studied. Maximum frequency of driving signal on a wire is limited by its input rise time, fall time, pulse width, and the coupling effect from its neighbors. The analytical expressions to estimate the deterministic jitter time due to these effects are presented. The estimation is based on the fastest and slowest approximation of the signal waveform components. Also, we have extracted the eye opening parameters of the eye diagram. The inductance effects significance is shown on eye opening and jitter time. The 45nm technology is used for estimating the horizontal and vertical eye opening and jitter time. The presented...
Efficient cooperative cyclostationary spectrum sensing in cognitive radios at low SNR regimes
, Article IEEE Transactions on Wireless Communications ; Volume 10, Issue 11 , 2011 , Pages 3754-3764 ; 15361276 (ISSN) ; Le Ngoc, T ; Nasiri Kenari, M ; Sharif University of Technology
Abstract
This paper proposes efficient cooperative cyclostationary spectrum sensing schemes in which each secondary-user (SU) performs single-cycle (SC) cyclostationary detection for fast and simple implementation, while collaboration between SUs in final decision on the presence or absence of the primary-user (PU) is explored to improve its performance. As the SUs simultaneously measure the spectral correlation functions at different cycle-frequencies (CF) and exchange their information regarding the measured results, a sufficient number of CFs are effectively examined with parallel searching, which makes the proposed cooperative spectrum sensing more reliable. This paper presents another look at...
Almost zero-jitter optical clock recovery using all-optical kerr shutter switching techniques
, Article Journal of Lightwave Technology ; Volume 33, Issue 9 , February , 2015 , Pages 1737-1747 ; 07338724 (ISSN) ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, a new all optical phase-locked loop (OPLL) is proposed and analyzed. The scheme relies on using two optical Kerr shutters to reveal the OPLL's error signal. The set of optical Kerr shutters and the subsequent low-speed photodetectors realize two nonlinear cross-correlations between the local clock pulse stream (called pump in Kerr shutter notations) and the time-shifted replicas of the incoming received data signal (called probe). The outputs of the cross-correlators are subtracted to form the error signal of the OPLL. We characterize the mathematical structure of the proposed OPLL and identify its two intrinsic sources of phase noise, namely, randomness of the received...
Multifractal analysis of light scattering-intensity fluctuations
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 80, Issue 6 , 2009 ; 15393755 (ISSN) ; Jabbari Farouji, S ; Movahed, M. S ; Jafari, G. R ; Rahimi Tabar, M. R ; Sharif University of Technology
Abstract
We provide a simple interpretation of non-Gaussian nature of the light scattering-intensity fluctuations from an aging colloidal suspension of Laponite using the multiplicative cascade model, Markovian method, and volatility correlations. The cascade model and Markovian method enable us to reproduce most of recent empirical findings: long-range volatility correlations and non-Gaussian statistics of intensity fluctuations. We provide evidence that the intensity increments Δx (τ) =I (t+τ) -I (t), upon different delay time scales τ, can be described as a Markovian process evolving in τ. Thus, the τ dependence of the probability density function p (Δx,τ) on the delay time scale τ can be...
Low-drift optoelectronic oscillator based on a phase modulator in a sagnac loop
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 65, Issue 7 , 2017 , Pages 2617-2624 ; 00189480 (ISSN) ; Banai, A ; Kartner, F. X ; Sharif University of Technology
Abstract
A low-drift optoelectronic oscillator (OEO) is developed and experimentally shown. In the proposed OEO, a fiber Sagnac interferometer, including an optical phase modulator (PM) and a nonreciprocal bias unit, functions as an intrinsically drift-free intensity modulator. The phase noise of the proposed OEO is modeled in phase space, which is verified by experiments. Phase noise and frequency stability of the photonically generated microwave signals are measured. The single-sideband phase noise of the generated microwave signal is -106.6 dBc/Hz at 10-kHz offset from the 10.833-GHz carrier, with 120-fs rms timing jitter integrated from 1 kHz to 10 MHz. Frequency drift measurements show ±0.85-ppm...
Tunable low-Jitter low-drift spurious-free transposed-frequency optoelectronic oscillator
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 65, Issue 7 , 2017 , Pages 2625-2635 ; 00189480 (ISSN) ; Banai, A ; Kartner, F. X ; Sharif University of Technology
Abstract
We propose and theoretically and experimentally demonstrate a novel tunable spurious-free single-loop optoelectronic oscillator (OEO) with low drift and low-phase noise. In the proposed transposed-frequency OEO (TF-OEO), a nonreciprocal bias unit and an optical phase modulator in a fiber Sagnac interferometer function jointly as an intrinsically drift-free intensity modulator, which improves the long-term drift. Besides, a transposed-frequency low-noise filtered amplifier is used which replaces the conventional radio frequency (RF) bandpass filter (BPF) and RF amplifier with an intermediate frequency (IF) BPF, an ultralow phase noise IF amplifier, and a tunable local oscillator, to attain...
Performance limits of optical clock recovery systems based on two-photon absorption detection scheme
, Article IEEE Journal on Selected Topics in Quantum Electronics ; Volume 14, Issue 3 , 2008 , Pages 963-971 ; 1077260X (ISSN) ; Salehi, J. A ; Sharif University of Technology
2008
Abstract
In this paper, we analyze and discuss the performance limits of optical clock recovery systems using a phase-locked loop (PLL) structure with nonlinear two-photon absorption (TPA) phase detection scheme. The motivation in analyzing the aforementioned optical PLL with TPA receiver structure is due to a recent successful experiment reported in [8]. We characterize the mathematical structure of PLLs with TPA, so as to evaluate the performance limits on optical clock recovery mechanism. More specifically, we identify two intrinsic sources of phase noise in the system namely, the ON-OFF nature of the incoming data pulses and the detector's shot noise that ultimately limit the performance of the...