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Sökning: WFRF:(Angelov A)

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1.
  • Aamodt, K., et al. (författare)
  • Alignment of the ALICE Inner Tracking System with cosmic-ray tracks
  • 2010
  • Ingår i: Journal of Instrumentation. - 1748-0221. ; 5
  • Konferensbidrag (refereegranskat)abstract
    • ALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 mu m in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10(5) charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.
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2.
  • Aamodt, K., et al. (författare)
  • First proton-proton collisions at the LHC as observed with the ALICE detector: measurement of the charged-particle pseudorapidity density at root s=900 GeV
  • 2010
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 65:1-2, s. 111-125
  • Tidskriftsartikel (refereegranskat)abstract
    • On 23rd November 2009, during the early commissioning of the CERN Large Hadron Collider (LHC), two counter-rotating proton bunches were circulated for the first time concurrently in the machine, at the LHC injection energy of 450 GeV per beam. Although the proton intensity was very low, with only one pilot bunch per beam, and no systematic attempt was made to optimize the collision optics, all LHC experiments reported a number of collision candidates. In the ALICE experiment, the collision region was centred very well in both the longitudinal and transverse directions and 284 events were recorded in coincidence with the two passing proton bunches. The events were immediately reconstructed and analyzed both online and offline. We have used these events to measure the pseudorapidity density of charged primary particles in the central region. In the range vertical bar eta vertical bar < 0.5, we obtain dN(ch)/d eta = 3.10 +/- 0.13(stat.) +/- 0.22(syst.) for all inelastic interactions, and dN(ch)/d eta = 3.51 +/- 0.15(stat.) +/- 0.25(syst.) for nonsingle diffractive interactions. These results are consistent with previous measurements in proton-antiproton interactions at the same centre-of-mass energy at the CERN Sp<(p)over bar>S collider. They also illustrate the excellent functioning and rapid progress of the LHC accelerator, and of both the hardware and software of the ALICE experiment, in this early start-up phase.
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3.
  • Aamodt, K., et al. (författare)
  • Midrapidity Antiproton-to-Proton Ratio in pp Collisons root s=0.9 and 7 TeV Measured by the ALICE Experiment
  • 2010
  • Ingår i: Physical Review Letters. - 1079-7114. ; 105:7
  • Tidskriftsartikel (refereegranskat)abstract
    • The ratio of the yields of antiprotons to protons in pp collisions has been measured by the ALICE experiment at root s = 0.9 and 7 TeV during the initial running periods of the Large Hadron Collider. The measurement covers the transverse momentum interval 0.45 < p(t) < 1.05 GeV/c and rapidity vertical bar y vertical bar < 0.5. The ratio is measured to be R-vertical bar y vertical bar<0.5 = 0.957 +/- 0.006(stat) +/- 0.0014(syst) at 0.9 Tev and R-vertical bar y vertical bar<0.5 = 0.991 +/- 0.005 +/- 0.014(syst) at 7 TeV and it is independent of both rapidity and transverse momentum. The results are consistent with the conventional model of baryon-number transport and set stringent limits on any additional contributions to baryon-number transfer over very large rapidity intervals in pp collisions.
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4.
  • Aamodt, K., et al. (författare)
  • Production of pions, kaons and protons in pp collisions at root s=900 GeV with ALICE at the LHC
  • 2011
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 71:6
  • Tidskriftsartikel (refereegranskat)abstract
    • The production of pi(+), pi(-), K+, K-, p, and (p) over bar at mid-rapidity has been measured in proton-proton collisions at root s = 900 GeV with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum (p(t)) spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges, the results are combined to extract spectra from p(t) = 100 MeV/c to 2.5 GeV/c. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean pt are compared with previous measurements, and the trends as a function of collision energy are discussed.
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5.
  • Aamodt, K., et al. (författare)
  • Transverse momentum spectra of charged particles in proton-proton collisions at root s=900 GeV with ALICE at the LHC
  • 2010
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 693:2, s. 53-68
  • Tidskriftsartikel (refereegranskat)abstract
    • The inclusive charged particle transverse momentum distribution is measured in proton-proton collisions at root s = 900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (vertical bar eta vertical bar < 0.8) over the transverse momentum range 0.15 < p(T) < 10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for vertical bar eta vertical bar < 0.8 is < p(T)>(INEL) = 0.483 +/- 0.001 (stat.) +/- 0.007 (syst.) GeV/c and < p(T)>(NSD) = 0.489 +/- 0.001 (stat.) +/- 0.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger < p(T)> than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET. (C) 2010 Published by Elsevier B.V.
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6.
  • Aamodt, K., et al. (författare)
  • Two-pion Bose-Einstein correlations in pp collisions at root s=900 GeV
  • 2010
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 82:5
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the measurement of two-pion correlation functions from pp collisions at root s = 900 GeV performed by the ALICE experiment at the Large Hadron Collider. Our analysis shows an increase of the Hanbury Brown-Twiss radius with increasing event multiplicity, in line with other measurements done in particle- and nuclear collisions. Conversely, the strong decrease of the radius with increasing transverse momentum, as observed at the Relativistic Heavy Ion Collider and at Tevatron, is not manifest in our data.
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7.
  • Aamodt, K., et al. (författare)
  • Charged-particle multiplicity measurement in proton-proton collisions at root s=0.9 and 2.36 TeV with ALICE at LHC
  • 2010
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 68:1-2, s. 89-108
  • Tidskriftsartikel (refereegranskat)abstract
    • Charged-particle production was studied in proton-proton collisions collected at the LHC with the ALICE detector at centre-of-mass energies 0.9 TeV and 2.36 TeV in the pseudorapidity range vertical bar eta vertical bar < 1.4. In the central region (vertical bar eta vertical bar < 0.5), at 0.9 TeV, we measure charged-particle pseudo-rapidity density dN(ch)/d eta = 3.02 +/- 0.01(stat.)(-0.05)(+0.08)(syst.) for inelastic interactions, and dN(ch)/d eta = 3.58 +/- 0.01 (stat.)(-0.12)(+0.12)(syst.) for non-single-diffractive interactions. At 2.36 TeV, we find dN(ch)/d eta = 3.77 +/- 0.01(stat.)(-0.12)(+0.25)(syst.) for inelastic, and dN(ch)/d eta = 4.43 +/- 0.01(stat.)(-0.12)(+0.17)(syst.) for non-single-diffractive collisions. The relative increase in charged-particle multiplicity from the lower to higher energy is 24.7% +/- 0.5%(stat.)(-2.8)(+5.7)%(syst.) for inelastic and 23.7% +/- 0.5%(stat.)(-1.1)(+4.6)%(syst.) for non-single-diffractive interactions. This increase is consistent with that reported by the CMS collaboration for non-single-diffractive events and larger than that found by a number of commonly used models. The multiplicity distribution was measured in different pseudorapidity intervals and studied in terms of KNO variables at both energies. The results are compared to proton-antiproton data and to model predictions.
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8.
  • Aamodt, K., et al. (författare)
  • Charged-particle multiplicity measurement in proton-proton collisions at root s=7 TeV with ALICE at LHC
  • 2010
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 68:3-4, s. 345-354
  • Tidskriftsartikel (refereegranskat)abstract
    • The pseudorapidity density and multiplicity distribution of charged particles produced in proton-proton collisions at the LHC, at a centre-of-mass energy root s = 7 TeV, were measured in the central pseudorapidity region vertical bar eta vertical bar < 1. Comparisons are made with previous measurements at root s = 0.9 TeV and 2.36 TeV. At root s = 7 TeV, for events with at least one charged particle in |eta vertical bar| < 1, we obtain dN(ch)/d eta = 6.01 +/- 0.01(stat.)(-0.12)(+0.20) (syst.). This corresponds to an increase of 57.6%+/-0.4%(stat.)(-1.8%)(+3.6) (syst.) relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution.
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9.
  • Aamodt, K., et al. (författare)
  • The ALICE experiment at the CERN LHC
  • 2008
  • Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
  • Forskningsöversikt (refereegranskat)abstract
    • ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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12.
  • Mueller, T., et al. (författare)
  • Characterization and intercomparison of aerosol absorption photometers : result of two intercomparison workshops
  • 2011
  • Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 4:2, s. 245-268
  • Tidskriftsartikel (refereegranskat)abstract
    • Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate.
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13.
  • Avolio, G., et al. (författare)
  • Millimeter-Wave FET Nonlinear Modelling Based on the Dynamic-Bias Measurement Technique
  • 2014
  • Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 62:11, s. 2526-2537
  • Tidskriftsartikel (refereegranskat)abstract
    • In the paper, the nonlinear model of a microwave transistor is extracted from large-signal measurements acquired under "dynamic-bias" operation. Specifically, the transistor is driven by low-frequency large signals while a high-frequency tickle is applied on top of them. The low-frequency large signals, along with the dc bias voltages, set the large-signal operating point which represents a dynamic-bias condition for the device under test. Thanks to this technique, one can get at once and separately the nonlinear currents and charges of the transistor as a result of a very few nonlinear measurements. Additionally, the proposed technique allows one to accurately reconstruct the time-domain waveforms at the device-under-test terminals while the frequency of the tickle can be set as high as the bandwidth of today's vector calibrated nonlinear measurement systems (i.e., 67 GHz). The approach, which is general and independent of device technology, is applied on a 0.15-mu m GaAs pHEMT specifically designed for resistive cold-FET mixer applications.
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14.
  • Avolio, G., et al. (författare)
  • Nonlinear model for 40-GHz cold-FET operation
  • 2014
  • Ingår i: International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, INMMiC 2014.
  • Konferensbidrag (refereegranskat)abstract
    • We extract the nonlinear model of a 0.15 μm GaAs pHEMT for cold-FET mixer applications. The model parameters are extracted from experimental data obtained by simultaneously driving the device under test with low-frequency large signals and a tickle tone at the RF operating frequency. The advantage of this approach is twofold. Firstly, as a result of a single measurement one can get separately the nonlinear currents and charge. Secondly, one can perform nonlinear characterization, and subsequently modeling, even if the RF frequency is such that its harmonics cannot be measured by today's nonlinear network vector analyzers.
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15.
  • Avolio, G., et al. (författare)
  • Small-Versus Large-Signal Extraction of Charge Models of Microwave FETs
  • 2014
  • Ingår i: IEEE Microwave and Wireless Components Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-1764 .- 1531-1309. ; 24:6, s. 394-396
  • Tidskriftsartikel (refereegranskat)abstract
    • In this letter we extract the parameters of the charge equations of a microwave transistor nonlinear model which is available in commercial CAD tools. In particular, the charge model parameters are extracted starting from small- and large-signal measurements. A better accuracy can be achieved when using large-signal measurements since the model parameters are obtained from experimental data which better reproduce the actual operating condition of the device under test. An advanced 0.15 x 300 mu m(2) pHEMT in GaAs technology, aimed at cold-FET mixer design, is considered as case study.
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16.
  • Crupi, G., et al. (författare)
  • Purely analytical extraction of an improved nonlinear FinFET model including non-quasi-static effects
  • 2009
  • Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317. ; 86:11, s. 2283-2289
  • Tidskriftsartikel (refereegranskat)abstract
    • An analytical procedure is proposed for extracting a new nonlinear FinFET model, which accounts for non-quasi static effects. The accuracy and the robustness of the obtained nonlinear model are completely validated through the comparison between simulated and measured device behaviour in both linear and nonlinear cases. This study clearly shows that the inclusion of the non-quasi-static phenomena leads to significant model simulation improvements, which become more pronounced at higher frequency. (C) 2009 Elsevier B.V. All rights reserved.
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17.
  • Abbasi, Morteza, 1982, et al. (författare)
  • Single-Chip 220-GHz Active Heterodyne Receiver and Transmitter MMICs With On-Chip Integrated Antenna
  • 2011
  • Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 59:2, s. 466-478
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the design and characterization of single-chip 220-GHz heterodyne receiver (RX) and transmitter (TX) monolithic microwave integrated circuits (MMICs) with integrated antennas fabricated in 0.1-mu m GaAs metamorphic high electron-mobility transistor technology. The MMIC receiver consists of a modified square-slot antenna, a three-stage low-noise amplifier, and a sub-harmonically pumped resistive mixer with on-chip local oscillator frequency multiplication chain. The transmitter chip is the dual of the receiver chip by inverting the direction of the RF amplifier. The chips are mounted on 5-mm silicon lenses in order to interface the antenna to the free space and are packaged into two separate modules. The double-sideband noise figure (NF) and conversion gain of the receiver module are measured with the Y-factor method. The total noise temperature of 1310 +/- 100K(corresponding to an NF of 7.4 dB), including the losses in the lens and antenna, is measured at 220 GHz with a respective conversion gain of 3.5 dB. The radiated continuous-wave power from the transmitter module is measured to be up to -6 dBm from 212 to 226 GHz. The transmitter and receiver are linked in a quasi-optical setup and the IF to IF response is measured to be flat up to 10 GHz. This is verified to be usable for transmission of a 12.5-Gb/s data stream between the transmit and receive modules over a 0.5-m wireless link. The modules operate with a 1.3-V supply and each consume 110-mW dc power. The presented 220-GHz integrated circuits and modules can be used in a variety of applications, including passive and active imaging, as well as high-speed data communications. To the best of our knowledge, these MMICs are the highest frequency single-chip low-noise heterodyne receiver and transmitter pair reported to date.
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18.
  • Abbasi, Morteza, 1982, et al. (författare)
  • Single-Chip Frequency Multiplier Chains for Millimeter-Wave Signal Generation
  • 2009
  • Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 57:12, s. 3134-3142
  • Tidskriftsartikel (refereegranskat)abstract
    • Two single-chip frequency multiplier chains targeting 118 and 183 GHz output frequencies are presented. The chips are fabricated in a 0.1 mu m GaAs metamorphic high electron-mobility transistor process. The D-band frequency doubler chain covers 110 to 130 GHz with peak output power of 5 dBm. The chip requires 2 dBm input power and consumes only 65 mW of dc power. The signal at the fundamental frequency is suppressed more than 25 dB compared to the desired output signal over the band of interest. The G-band frequency sextupler (x6) chain covers 155 to 195 GHz with 0 dBm peak output power and requires 6.5 dBm input power and 92.5 mW dc power. The input signal to the multiplier chain can be reduced to 4 dBm while the output power drops only by 0.5 dB. The unwanted harmonics are suppressed more than 30 dB compared to the desired signal. An additional 183 GHz power amplifier is presented to be used after the x6 frequency multiplier chain if higher output power is required. The amplifier delivers 5 dBm output power with a small-signal gain of 9 dB from 155 to 195 GHz. The impedance matching networks are realized using coupled transmission lines which is shown to be a scalable and straightforward structure to use in amplifier design. Microstrip transmission lines are used in all the designs.
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19.
  • Angelov, B., et al. (författare)
  • An integrated model for designing of technical systems : Another step to coherence between theory and practice
  • 2020
  • Ingår i: IOP Conference Series. - : Institute of Physics Publishing (IOPP).
  • Konferensbidrag (refereegranskat)abstract
    • A number of authors recommend selecting the systems design methods to be used depending on the practical tasks to be solved. At the same time, results of studies aiming at clarifying and systematizing practical tasks are very rare. In the frames of the research performed, it was revealed that in the companies four major tasks use to be solved - adapting an existing solution to work in new conditions, refining an existing solution, combining it with previously developed elements and creating a new solution. Resultantly, in the research an integrated model for design of technical systems was proposed. This model was obtained by combining (overlaying) the methods for solving the four main tasks defined and subsequently the content of the different stages in the proposed model was clarified. © Published under licence by IOP Publishing Ltd.
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20.
  • Angelov, Iltcho, 1943, et al. (författare)
  • Hybrid measurement-based extraction of consistent large-signal models for microwave FETs
  • 2013
  • Ingår i: 43rd European Microwave Conference, EuMC 2013 - Held as Part of the 16th European Microwave Week, EuMW 2013; Nuremberg; Germany; 7 October 2013 through 10 October 2013. - 9782874870316 ; , s. 267-270
  • Konferensbidrag (refereegranskat)abstract
    • This paper discusses a procedure to extract large-signal models for microwave transistors. By using experimental data, which not necessarily reflect the actual operating conditions, accurate large-signal models, suitable for CAD tools and working at high frequencies, can be obtained by combining direct extraction of basic parameters and numerical optimization. The idea consists of linking the model parameters directly to experimental data. In this way the extraction procedure is sped up. Examples of large-signal models for GaAs and GaN transistors are reported.
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21.
  • Angelov, Iltcho, 1943, et al. (författare)
  • Large signal evaluation of nonlinear HBT model
  • 2007
  • Ingår i: IEICE Transactions on Electronics. - : Institute of Electronics, Information and Communications Engineers (IEICE). - 0916-8524 .- 1745-1353. ; E91C:7, s. 1091-1097
  • Konferensbidrag (refereegranskat)abstract
    • The performance of recently developed Large Signal (LS) HBT model was evaluated with extensive LS measurements like Power spectrum, Load pull and Inter-modulation investigations. Proposed model has adopted temperature dependent leakage resistance and a simplified capacitance models. The model was implemented in ADS as SDD. Important feature of the model is that the main model parameters are taken directly from measurements in rather simple and understandable way. Results show good accuracy despite the simplicity of the model. To our knowledge the HBT model is one of a few HBT models which can handle high current & Power HBT devices, with significantly less model parameters with good accuracy.
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22.
  • Angelov, Iltcho, 1943, et al. (författare)
  • On the Large Signal Evaluation and Modeling of GaN FET
  • 2010
  • Ingår i: IEICE Transactions on Electronics. - 0916-8524. ; E93C:8, s. 1225-1233
  • Tidskriftsartikel (refereegranskat)abstract
    • The large signal performance and model for GaN FET devices was evaluated with DC, S-parameters, and large signal measurements. The large signal model was extended with bias and temperature dependence of access resistances, modified capacitance and charge equations, as well as breakdown models. The model was implemented in a commercial CAD tool and exhibits good overall accuracy.
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23.
  • Avolio, G., et al. (författare)
  • A novel technique for the extraction of nonlinear model for microwave transistors under dynamic-bias operation
  • 2013
  • Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467361767 ; , s. Art. no. 6697394-
  • Konferensbidrag (refereegranskat)abstract
    • In this work we describe a novel technique for the extraction of nonlinear model for microwave transistors from nonlinear measurements obtained by simultaneously driving the device under test with low- and high-frequency excitations. Specifically, the large-signal operating point of the device is set by large-signal low-frequency excitations. On top of these a tickle tone at high-frequency is applied. In this way, one can separate the contributions of the IDS current source and the charge sources by a single measurement. The nonlinear model, based on equations available in commercial CAD tools, is extracted for a 0.15 μm GaAs pHEMT. Good agreement is obtained between model predictions and experimental data.
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24.
  • Avolio, G., et al. (författare)
  • A procedure for the extraction of a nonlinear microwave GaN FET model
  • 2017
  • Ingår i: International Journal of Numerical Modelling: Electronic Networks, Devices and Fields. - : Wiley. - 0894-3370 .- 1099-1204. ; 30:1, s. UNSP e2151-
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we describe an extraction procedure of nonlinear models for microwave field-effect transistor (FET). We use a nonlinear model available in commercial CAD tools, and we extract the parameters by combining direct extraction and numerical optimization. We determine a first estimate of the model parameters by few DC and S-parameter measurements. Next, we refine the parameters by optimization against low-frequency and high-frequency vector-calibrated large-signal measurements gathered with a Large-Signal-Network Analyzer (LSNA). As case study we consider a 0.25x200 mu m(2) GaN FET on SiC for power amplifier applications. Ultimately, we want to show that a good accuracy level can be achieved while minimizing the extraction effort and that an accurate model can be built and suitably tailored depending on the final application.
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25.
  • Avolio, G., et al. (författare)
  • Identification technique of FET model based on vector nonlinear measurements
  • 2011
  • Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 47:24, s. 1323-U37
  • Tidskriftsartikel (refereegranskat)abstract
    • A new modelling approach which exploits only vector nonlinear measurements is described. The parameters of the I-V and Q-V nonlinear constitutive functions are identified by combining low-and high-frequency large-signal measurements with a numerical optimisation routine. Low-frequency dispersion manifesting in the I-V characteristics is also correctly accounted for. As a case study a gallium nitride HEMT on silicon carbide substrate is considered and very good agreement between measurements and simulation is achieved.
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26.
  • Avolio, G., et al. (författare)
  • Waveforms-based large-signal identification of transistor models
  • 2012
  • Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
  • Konferensbidrag (refereegranskat)abstract
    • Measurements of low-and high-frequency vector-calibrated large-signal waveforms are exploited in this work to identify the parameters of a FET nonlinear model. The I DS nonlinear current source and the nonlinear charge sources' parameters are respectively determined from a small set of low-(2 MHz) and high-frequency (8 GHz) load-pull measurements by using a least square numerical optimization. Under low-frequency operation the contribution of the charge sources and any other reactive element can be neglected. In this way the identification of the IDS parameters is more accurate while remarkably speeding up the optimization routine as well. The proposed procedure is quite general and can be applied to different types of active devices. As case study, a 0.25-μm GaAs pHEMT is considered and the extracted model is validated under conditions different than the ones exploited within the identification step. A very good agreement between model predictions and experimental data is achieved.
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27.
  • Crupi, G., et al. (författare)
  • Analysis of quasi-static assumption in nonlinear finFET model
  • 2008
  • Ingår i: 2008 17th International Conference on Microwaves, Radar and Wireless Communications, MIKON 2008. - 9788390666280
  • Konferensbidrag (refereegranskat)abstract
    • The construction and validation of a quasi-static nonlinear microwave model for FinFETs are investigated. A very good agreement between model simulations and measurements is obtained under different DC bias points, input power levels, fundamental frequencies up to 5 GHz, and device geometries. Since the intrinsic part of the FET model is based on the quasi-static approximation, the goal of this work is to analyze in detail the limitations of this assumption by examining the intrinsic admittance parameters versus the frequency.
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28.
  • Crupi, G., et al. (författare)
  • Combined empirical and look-up table approach for non-quasi-static modelling of GaN HEMTs
  • 2009
  • Ingår i: 9th International Conference on Telecommunications in Modern Satellite, Cable, and Broadcasting Services, TELSIKS 2009 - Proceedings of Paper. - 9781424443833 ; , s. 40-43
  • Konferensbidrag (refereegranskat)abstract
    • In this paper the empirical and the look-up table approaches are combined to accurately model a gallium nitride based HEMT on silicon carbide. That solution allows to exploit the advantages of both approaches. The validity of the extracted model is verified by comparing model simulations with DC and microwave measurements.
  •  
29.
  • Crupi, G., et al. (författare)
  • Non-linear FinFET Modeling: Lookup Table and Empirical Approaches
  • 2008
  • Ingår i: International Journal of Microwave and Optical Technology. - 1553-0396. ; 3:3, s. 157-164
  • Tidskriftsartikel (refereegranskat)abstract
    • The non-linear microwave modeling of advanced transistors is becoming more and more essential to the design and fabrication processes. Consequently, this study is focused on the equivalent circuit based non-linear microwave modeling of FinFET. An accurate multi-bias small signal equivalent circuit is extracted and subsequently used for analytically constructing a non-linear full blown lookup table model. Furthermore, an alternative model implementation, which is based on empirical expressions, is investigated. The validity of both non-linear modeling approaches is confirmed by the good agreement between model simulations and large signal measurements.
  •  
30.
  • Medina, M. A.Yarleque, et al. (författare)
  • Doherty amplifier design for 3.5 GHz WiMAX considering load line and loop stability
  • 2008
  • Ingår i: 2008 European Microwave Integrated Circuit Conference, EuMIC 2008; Amsterdam; Netherlands; 27 October 2008 through 31 October 2008. - 9782874870071 ; , s. 1549-1552
  • Konferensbidrag (refereegranskat)abstract
    • Legacy Doherty amplifier is characterized by using a larger transistor for the peak amplifier such that this reaches saturation with a smaller excitation signal. However due to device availability and modelling considerations, this is not often feasible. In this paper, the design and measurement of a Doherty amplifier utilizing only single sized device is realized. Unlike previous research works, intrinsic load line is utilized to tune the offset lines, as well as to verify the actual dynamic load principle. Stability aspects are covered for this type of amplifier, which are not normally included in earlier works. Finally an assessment of its applicability and benefits for WiMAX at 3.5 GHz is realized using a class AB amplifier as a comparison basis.
  •  
31.
  • Oishi, Toshiyuki, et al. (författare)
  • Semi-physical nonlinear model for HEMTs with simple equations
  • 2010
  • Ingår i: 2010 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, INMMiC 2010; Goteborg; 26 April 2010 through 27 April 2010. - 9781424474127 ; , s. 20-23
  • Konferensbidrag (refereegranskat)abstract
    • A Nonlinear Circuit Model (NCM) combined with device/physical parameters was developed by using hyperbolic tangent (tanh) function and applied to GaN high electron mobility transistors (HEMTs). The equations for the NCM were constructed to reproduce the results of a device physical simulation. Model parameters are similar with the parameters used in the device design. The simulated DC and capacitance characteristics agree well with the measurement data over wide voltage range. Furthermore, numbers of the parameters were reduced to only 17 by using common physical parameters to both drain current and capacitance models. © 2010 IEEE.
  •  
32.
  • Otsuka, Hiroshi, et al. (författare)
  • Semi-physical nonlinear circuit model with device/physical parameters for HEMTs
  • 2011
  • Ingår i: International Journal of Microwave and Wireless Technologies. - 1759-0787 .- 1759-0795. ; 3:1, s. 25-33
  • Tidskriftsartikel (refereegranskat)abstract
    • A nonlinear circuit model (NCM) with physical parameters is proposed for direct simulation of the RF characteristics of GaN high-electron-mobility transistors (GaN HEMTs) on the basis of device structure. The physical equations are used for the construction of the model in order to connect strongly the model parameters with the device/physical parameters. Hyperbolic tangent functions are used as the model equations to ensure good model convergence and rapid simulation (short simulation time). The usefulness of these equations is confirmed by technology computer aided design (TCAD) simulation. The number of model parameters for the nonlinear components (Ids, Cgs, Cgd) is reduced to 17 by using common physical parameters for modeling the drain current and capacitance. The accuracy of this model is verified by applying to GaN HEMTs. The modeled I–V and capacitance characteristics agree well with the measurement data over a wide voltage range. Furthermore, this model can be used for the accurate evaluation of S-parameters and large-signal RF characteristics.
  •  
33.
  • Zirath, Herbert, 1955, et al. (författare)
  • Integrated receivers up to 220 GHz utilizing GaAs-mHEMT technology
  • 2009
  • Ingår i: 2009 IEEE International Symposium on Radio-Frequency Integration Technology, RFIT 2009; Singapore; Singapore; 9 January 2009 through 11 January 2009. - 9781424450305 ; , s. 225-228
  • Konferensbidrag (refereegranskat)abstract
    • The status of integrated receivers for remote sensing and communication applications from 60 GHz to higher frequencies is reviewed. Recent receiver results for silicon and III-V technologies are compared with Schottky diode receivers.
  •  
34.
  • Zirath, Herbert, 1955, et al. (författare)
  • On the status of Low Noise Millimeterwave MMIC Receivers
  • 2009
  • Ingår i: APMC: 2009 ASIA PACIFIC MICROWAVE CONFERENCE. - 9781424428014 ; 1-5, s. 1303-1306
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The status of integrated receivers for remote sensing and communication applications from 60 GHz to higher frequencies is reviewed. Recent receiver results for silicon and technologies are compared with Schottky diode receivers.
  •  
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