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    Adaptive filtering techniques in passive radar

    , Article Proceedings International Radar Symposium, Dresden ; Volume 2 , June , 2013 , Pages 1067-1078 ; 21555753 (ISSN) ; 9783954042234 (ISBN) Chitgarha, M. M ; Radmard, M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
    One of the most important obstacles in passive radar applications is removing the direct signal from the target channel. Otherwise, week echoes from the targets in the target channel would be ignored due to the limited dynamic range of the system. One of the most effective techniques in this field is using adaptive filters. In this paper various adaptive filters are introduced and their performances are shown and compared  

    A wide dynamic range low power 2× time amplifier using current subtraction scheme

    , Article 2016 IEEE International Symposium on Circuits and Systems, ISCAS 2016, 22 May 2016 through 25 May 2016 ; Volume 2016-July , 2016 , Pages 462-465 ; 02714310 (ISSN); 9781479953400 (ISBN) Molaei, H ; Khorami, A ; Hajsadeghi, K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    The most challenging issue of conventional Time Amplifiers (TAs) is their limited Dynamic Range (DR). This paper presents a mathematical analysis to clarify principle of operation of conventional 2× TA's. The mathematical derivations release strength reduction of the current sources of the TA is the simplest way to increase DR. Besides, a new technique is presented to expand the Dynamic Range (DR) of conventional 2× TAs. Proposed technique employs current subtraction in place of changing strength of current sources using conventional gain compensation methods, which results in more stable gain over a wider DR. The TA is simulated using Spectre-rf in TSMC 0.18um COMS technology. DR of the 2×... 

    A high dynamic range CMOS variable gain filter for ADSL

    , Article 2002 IEEE International Symposium on Circuits and Systems, Phoenix, AZ, 26 May 2002 through 29 May 2002 ; Volume 4 , 2002 , Pages IV/257-IV/260 ; 02714310 (ISSN) Mehrmanesh, S ; Atarodi, M ; IEEE ; Sharif University of Technology
    A 3rd order, 1.1 MHz, lowpass butterworth Gm-c filter has been combined with a low noise Variable Gain Amplifier to form the Variable Gain Filter (VGF). In this VGF an improved transconductor is used and a new method is used to adjust the transconductance gain for tuning application. A continuous variable gain current-to-current converter is used to tune the transconductor value. The THD of the VGF is -85 dB for 1 Vppd input signal and -50 dB for 3 Vppd input signal. VGF gain can be varied from 0 to 31 dB with 1 dB variation steps. Input referred noise is 20 nV/√Hz for maximum gain. All the circuits are designed based on a 0.25 μm CMOS process technology  

    The Analysis of HDR Video Reconstruction Methods

    , M.Sc. Thesis Sharif University of Technology Ghaffari, Mahdi (Author) ; Amini, Arash (Supervisor)
    The conventional cameras and displays do not have the ability to record and display the full brightness of the world around us. These deficiencies have led to the development of methods known as High Dynamic Range Imaging. Most of the work done in this field falls into two groups: compression of the light range and its expansion. In compression, the brightness range is intended to display content with a high dynamic range in simple displays. But the goal of expanding the brightness range is to reconstruct HDR content from a low dynamic range one. In addition to the above classification, this field is also categorized based on the type of content (image or video). In this study, the... 

    HDR Image Reconstruction from a Single-Exposure LDR Image

    , M.Sc. Thesis Sharif University of Technology Shahbazi, Mohammad (Author) ; Amini, Arash (Supervisor) ; Mohammadzadeh, Nargesolhoda (Co-Supervisor)
    High dynamic range (HDR) images provide more realistic experience in displaying real-world scenes than conventional low dynamic range (LDR) images by providing much more detailed luminance information; However, most imaging content is still available in low dynamic range. Inverse tonemapping is known as the problem of inferring an HDR image from a single-exposure LDR image in which the lost data caused by saturation of bright parts and quantization must be reconstructed.To address this problem, in this thesis, two fully-automatic architectures based on convolutional neural networks, are proposed. Both these architectures utilize a number of convolutional auto-encoders as... 

    Design and implementation of a high dynamic range C band down-converter

    , Article Progress in Electromagnetics Research Letters ; Volume 31 , 2012 , Pages 25-33 ; 19376480 (ISSN) Saatchi, V ; Tavakoli, Z ; Sharif University ot Technology
    PIER Letters  2012
    A technique that expands dynamic range (DR) of frequency down-converters in the C band frequency is presented. Primary characteristics of down-converter are evaluated to confirm that it can be used in microwave receivers. The C band down-converter is carried out by the combination of RF mixers, band pass interdigital filter, and X band combline filter which are designed entirely for this project. Attainment of the perfect receiver is the final purpose of this paper, and a method that causes 72 dB dynamic range, high tangential signal sensitivity and fine gain flatness is used for achieving the mentioned purpose. These efforts improve the dynamic range about 19 dB and gain flatness about 3.07... 

    A 1.8V high dynamic range CMOS Gm-c filter for portable video systems

    , Article 14th International Conference on Microelectronics, ICM 2002, 11 December 2002 through 13 December 2002 ; Volume 2002-January , 2002 , Pages 38-41 ; 0780375734 (ISBN) Mehrmanesh, S ; Aslanzadeh, H. A ; Vahidfar, M. B ; Atarodi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2002
    A 4th order, 5 MHz, lowpass Butterworth Gm-c filter has been combined with a low noise low-voltage amplifier to form a lowpass filter for video applications. In this filter an improved transconductor and a powerful method is used to adjust the transconductance gain for tuning application. A continuous variable gain current-to-current converter is used to tune the transconductor value. The THD of the filter is -77 dB for 1 Vppd input signal. Input referred noise is 40 nV/√Hz in the worst case. All the circuits are designed based on a 0.25 μm CMOS process technology with a single 1.8 V supply. © 2002 IEEE  

    Comparison of two triple-fiber sensor designs for small distance measurements

    , Article Microwave and Optical Technology Letters ; Vol. 56, issue. 9 , JUN , 2014 , pp. 1997-2001 ; ISSN: 08952477 Golnabi, H ; Sharif University of Technology
    Operation of two different optical fiber sensor designs for distance measurements with a good sensitivity, resolution, and wide dynamic range is reported. Design is based on the intensity modulation due to reflectance measurement from a target surface. Two reported designs are fabricated with a triple-fiber assembly, in which one uses a double-transmitter, while another one uses a double-receiver fiber design. Reflection signals from different targets are tested with these sensors and results for the mirror and A4 paper surfaces are described. The response curve for both experiments starts from a near zero level, shows a maximum at a certain distance and gradually drops to the background... 

    Two-dimensional multi-parameter adaptation of noise, linearity, and power consumption in wireless receivers

    , Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Vol. 61, issue. 8 , July , 2014 , p. 2433-2443 Meghdadi, M ; Sharif Bakhtiar, M ; Sharif University of Technology
    This paper presents a general method for real-time adaptation of wireless receivers according to the prevailing reception conditions. In order to maintain the desired signal quality at the minimum possible power dissipation, the method performs an optimal trade-off between noise, linearity, and power consumption in the building blocks of the receiver. This is achieved by continuously monitoring the signal-to-noise plus interference ratio (SNIR) and accordingly tuning the adaptation parameters embedded in the receiver design. A prototype DVB-H receiver chip, implemented in a standard 0.18-μ m CMOS process, is used as the test vehicle. By properly trading noise with linearity in the receiver,... 

    A low-power, second-order Δ/∑ modulator using a single class-AB op-amp for voice-band applications

    , Article Analog Integrated Circuits and Signal Processing ; Volume 49, Issue 2 , 2006 , Pages 199-211 ; 09251030 (ISSN) Safarian, A ; Sahandiesfanjani, F ; Heydari, P ; Atarodi, S. M ; Sharif University of Technology
    The design of a power-efficient second-order Δ/∑ modulator for voice-band is presented. At system level, a new single-loop, single-stage modulator is proposed. The modulator employs only one class-AB op-amp to realize a second-order noise shaping for voice-band applications. The modulator is designed in a 0.25μm standard CMOS process, and exhibits 86 dB dynamic range (DR) for a 4 kHz voice-bandwidth. The proposed modulator consumes 125μW from a 2.5 V supply. © Springer Science + Business Media, LLC 2006  

    An enhanced dynamic range low-power delta-sigma modulator for portable voice band applications

    , Article 2003 Southwest Symposium on Mixed-Signal Design, SSMSD 2003, 23 February 2003 through 25 February 2003 ; 2003 , Pages 263-268 ; 0780377788 (ISBN); 9780780377783 (ISBN) Safarian, A. Q ; Aslanzadeh, H. A ; Mehrmanesh, S ; Vahidfar, M. B ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2003
    A new second order sigma delta modulator with the reduced number of op-amps, to decrease static power consumption and area, is presented for voice band applications such as codecs. This switched capacitor modulator uses reused capacitor technique to reduce the input thermal noise and circuit area. It improves the DR of modulator by almost 0.5 bit. The modulator shows 87 dB DR for voice band while consuming 125 μW from a 2.5 V supply. © 2003 IEEE  

    Construction of Pt nanoparticle-decorated graphene nanosheets and carbon nanospheres nanocomposite-modified electrodes: Application to ultrasensitive electrochemical determination of cefepime

    , Article RSC Advances ; Volume 4, Issue 15 , 2014 , Pages 7786-7794 ; ISSN: 20462069 Shahrokhian, S ; Hosseini Nassab, N ; Ghalkhani, M ; Sharif University of Technology
    A novel ultrasensitive modified electrode was fabricated with a graphene nanosheets and carbon nanospheres (GNS-CNS)-based nanocomposite film as a powerful platform. Pt nanoparticles (PtNPs) were simply electrodeposited onto the GNS-CNS-coated glassy carbon electrode creating a PtNPs/GNS-CNS hybrid nanocomposite modified electrode. Scanning electron microscopy, energy dispersive X-ray spectroscopy and linear sweep voltammetry (LSV) techniques were used for the characterization of the prepared modified electrode. The results of investigation of electrochemical response characteristics of cefepime (CP) revealed a considerable improvement in the oxidation peak current of CP on PtNPs/GNS-CNS/GCE... 

    A fast enhanced algorithm of PRI transform

    , Article Proceedings - 6th International Symposium on Parallel Computing in Electrical Engineering, PARELEC 2011, 4 April 2011 through 5 April 2011 ; April , 2011 , Pages 179-184 ; 9780769543970 (ISBN) Mahdavi, A ; Pezeshk, A. M ; Sharif University of Technology
    The problem of estimating pulse repetition interval (PRI) of an interleaved pulse train which consist of several independent radar signals, is the main issue of signal processing in electronic support systems. PRI Transform algorithm is one of the well known and effective methods of PRI detection which is capable of detecting several close jittered signals and surpassing subharmonics, but have some drawbacks especially because of small PRI dynamic range and heavy computations. In this paper a modified PRI transform is introduced which manage wide range of PRIs simultaneously, and speed up the algorithm by significantly reducing the computations. Moreover an efficient threshold is set for... 

    Construction of a modified carbon paste electrode based on TiO2 nanoparticles for the determination of gallic acid

    , Article Journal of Solid State Electrochemistry ; Volume 17, Issue 1 , 2013 , Pages 157-165 ; 14328488 (ISSN) Tashkhourian, J ; Nami Ana, S. F ; Hashemnia, S ; Hormozi Nezhad, M. R ; Sharif University of Technology
    A modified carbon paste electrode was prepared by incorporating the TiO2 nanoparticles in the carbon paste matrix. The electrochemical behavior of gallic acid (GA) is investigated on the surface of the electrode using cyclic voltammetry and differential pulse voltammetry. The surface morphology of the prepared electrode was characterized using the scanning electron microscopy. The results indicate that the electrochemical response of GA is improved significantly at the modified electrode compared with the unmodified electrode. Furthermore, the capabilities of electron transfer on these two electrodes were also investigated by electrochemical impedance spectroscopy. Under the optimized... 

    Performance analysis of an optical beam-forming network with custom microwave CAD tools

    , Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010, Isfahan ; 2010 , Pages 100-104 ; 9781424467600 (ISBN) Shabani, M ; Akbari, M ; Sharif University of Technology
    Next generation wideband and ultra-wideband radar antenna arrays need efficient true-time delay networks for array control. Optical beam-forming networks have been considered as a promising solution in such arrays. Performance analysis of optical beam-formers is thus quiet necessary. In this paper signal to noise ratio and dynamic range of simple optical beam-forming structures are investigated with a custom microwave CAD tool. Two structures with optical and RF power combining methods are discussed. With the proposed devices' parameters, the optical combining method shows better performance for low and moderate optical powers  

    An investigation on the performance of receiving optical beam-forming networks

    , Article Final Program and Book of Abstracts - iWAT 2010: 2010 International Workshop on Antenna Technology: Small Antennas, Innovative Structures and Materials, 1 March 2010 through 3 March 2010 ; March , 2010 ; 9781424448845 (ISBN) Shabani, M ; Akbari, M ; Sharif University of Technology
    Next generation wideband and ultra-wideband radar antenna arrays need efficient true-time delay networks for array control. Following the great interest for optical control of antenna array beam steering, performance analysis of optical beam-formers is a must. In this paper signal to noise ratio and dynamic range of simple optical beamforming structures with components off the shelf are investigated theoretically. Especially the effects of certain power combining components such as arrayed wave guide gratings, broadband passive optical combiners and microwave combiners inspected. It turns up that an efficient microwave combiner would surpass the optical combiners in both SNR and dynamic... 

    Performance characterization of a low-cost dual-channel camera-based microarray scanner

    , Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 1534-1538 ; 9781467387897 (ISBN) Akhoundi, F ; Ghobeh, M ; Ghiasvand, E ; Akbari Roshan, K ; Motahari, S. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    In this paper, we have proposed, designed, implemented, and characterized a low-cost camera-based microarray scanner which is capable of imaging fluorescently-labeled DNA or Protein microarrays. The proposed system is designed to simultaneously measure two different fluorescent dyes using two parallel channels which increase the overall scan speed. We have shown that the wide dynamic range of system makes it able to detect fluorophore densities from 100-106 molecule/μm2. In each capture, a 5.6 mm × 3.7 mm field is imaged on a 22.3 mm × 14.9 mm (18 megapixels) CMOS sensor. Therefore, the microarray can be scanned with ∼ 1μm2 spatial resolution which is high enough to distinguish borders of... 

    Fabrication of modified TiO 2 nanoparticle carbon paste electrode for simultaneous determination of dopamine, uric acid, and l-cysteine

    , Article Journal of Solid State Electrochemistry ; Volume 13, Issue 9 , 2009 , Pages 1433-1440 ; 14328488 (ISSN) Mazloum Ardakani, M ; Talebi, A ; Naeimi, H ; Nejati Barzoky, M ; Taghavinia, N ; Sharif University of Technology
    A carbon paste electrode, modified with 2, 2″-[1,7- hepthandiylbis(nitriloethylidyne)]-bis-hydroquinone and TiO 2 nanoparticles, was used for the simultaneous determination of dopamine (DA), uric acid (UA), and l-cysteine. The study was carried out by using cyclic voltammetry, chronoamperometry, and square wave voltammetry (SWV) techniques. Some kinetic parameters such as the electron transfer coefficient (α) and heterogeneous rate constant (k s) were also determined for the DA oxidation. A dynamic range of 8.0-1400 μM, with the detection limit of 8.4∈×∈10 -7 M for DA, was obtained using SWV (pH∈=∈7.0). The prepared electrode was successfully applied for the determination of DA, UA, and... 

    Beamforming, null-steering, and simultaneous spatial and frequency domain filtering in integrated phased array systems

    , Article AEU - International Journal of Electronics and Communications ; Volume 110 , 2019 ; 14348411 (ISSN) Karami, P ; Atarodi, S. M ; Sharif University of Technology
    Elsevier GmbH  2019
    In the case that phased array systems are not capable of attenuating interferences, Radio Frequency (RF) front-ends and Analog Digital Converters (ADCs) with a large dynamic range are required to avoid saturation of the receiver. This leads to a higher power consumption. In this paper, employing N-path circuits in Mixer-First receivers, a novel method is introduced in which spatial and frequency blockers are eliminated right before entering the system on the antennas input. In fact using this technique, adjustable spatial notch filter and band-pass frequency filter are implemented to suppress spatial and frequency interferences. The proposed method enhances the robustness and effectiveness... 

    Electrochemical determinations of 6-mercaptopurine on the surface of a carbon nanotube-paste electrode modified with a cobalt salophen complex

    , Article Journal of Solid State Electrochemistry ; Volume 16, Issue 4 , April , 2012 , Pages 1643-1650 ; 14328488 (ISSN) Shahrokhian, S ; Ghorbani Bidkorbeh, F ; Mohammadi, A ; Dinarvand, R ; Sharif University of Technology
    A mixture of multi-walled carbon nanotube/graphite paste electrode modified with a salophen complex of cobalt was prepared and was applied for the study of the electrochemical behavior of 6-mercaptopurine (MP) using cyclic and differential pulse voltammetry (DPV). An excellent electrocatalytic activity toward the oxidation of MP was achieved, which led to a considerable lowering in the anodic overpotential and remarkable increase in the response sensitivity in comparison with unmodified electrode. Utilizing DPV method, a linear dynamic range of 1-100 μM with detection limit of 0.1 μM was obtained in phosphate buffer of pH 3.0. The electrochemical detection system was very stable, and the...