Browsing by Subject "Amplifiers (electronic)"
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Item Open Access AlGaN/GaN HEMT-based fully monolithic X-band low noise amplifier(Wiley, 2005-04) Schwindt, R.; Kumar, V.; Aktas, O.; Lee, J. W.; Adesida, I.A fully monolithic AlGaN/GaN HEMT-based low noise amplifier is reported. The circuit demonstrated a noise figure of 3.5 dB, gain of -7.5 dB, input return loss of -7.5 dB, and output return loss of -15 dB at 8.5 GHz. The dc characteristics of individual 0.25-μm × 150-μm transistors were: maximum current density of 1.0 A/mm, maximum transconductance of 170 mS/mm and a threshold voltage of -6.8 V. The devices have a typical short circuit current gain cutoff frequency of 24.5 GHz and a maximum oscillating frequency of 48 GHz. The devices demonstrated a minimum noise figure of 1.6 dB with an associated gain of 10.6 dB at 10 GHz.Item Open Access Burst-mode Yb fiber amplifier producing 30 μJ individual pulse energy(Optical Society of America, 2012) Kalaycıoğlu, Hamit; Burak Eldeniz, Y.; İlday, F. Ömer; Eken, K.We report 30-μJ individual pulse energy for 150-ns long amplified bursts of 0.4 mJ total energy from a 1-kHz Yb-fiber amplifier. Non-uniformity of pulse energy distribution inside amplified bursts is significantly reduced. ©2012 Optical Society of America.Item Open Access Design of multi-octave band GaN-HEMT power amplifier(IEEE, 2012) Eren, Gulesin; Şen, Özlem A.; Bölükbaş, Basar; Kurt, Gökhan; Arıcan, Orkun; Cengiz, Ömer; Ünal, Sıla T.K.; Durmuş, Yıldırım; Özbay, EkmelThis paper describes design, fabrication and measurement of 6 GHz - 18 GHz monolithic microwave integrated circuit (MMIC) amplifier. The amplifier is realized as coplanar waveguide (CPW) circuit using 0.3 μm-gate Gallium-Nitride (GaN) HEMT technology. The amplifier has a small signal gain of 7 ± 0.75 dB. The output power at 3dB compression is better than 24 dBm with 16%-19% drain efficiency for the whole 6 GHz-18 GHz frequency band under continuous wave (CW) power. © 2012 IEEE.Item Open Access Distance laboratory applications ERRL: A study on radio communication in electronic field(IEEE, 2008-05) Aydın, C. Ç.; Türkmen, G.; Özyurt, E.; Aydın, E. U.; Çaǧıltay, N. E.; Özbek, M. E.; Alparslan, N. Ceren; Kara, A.In the last decade, the effect of internet usage in education is gradually increased. When we look from academic perspective, the new technologies provided alternatives for students learning. As distance education becomes important everyday, the indispensable elements of teaching and education, laboratories must be reachable via remote connection. Consequently, the education that is going to be given to the students will be more flexible with respect to place and time constraints and students can reach laboratory facilities at any time and anywhere not only in lectures and practical hours. In this study, European Remote Radio Laboratory (ERRL) which is a distance remote Radio Frequency (RF) laboratory designed for electrical-electronics students, is described generally. The software architecture, infrastructure and experiment that can be done with a remote connection have been described.Item Open Access Femtosecond Yb-doped fiber laser system at 1 μm of wavelength with 100-nm bandwidth and variable pulse structure for accelerator diagnostics(2007-05) Winter, A.; İlday, F. Ömer; Steffen, B.Laser-based diagnostic systems play an increasingly important role in accelerator diagnostics in, for instance, electron bunch length measurements. To date, the laser system of choice for electro-optic experiments has been the Ti:sapphire laser, providing several nanojoules of pulse energies at fixed a repetition rate, which is not well suited to the bunch structure of accelerator facilities such as FLASH. Limited long-term stability and operability of Ti:sapphire systems are significant drawbacks for a continuously running measurement system requiring minimal maintenance and maximum uptime. We propose fiber lasers as a promising alternative with significant advantages. Gating of the pulse train to match the bunch profile is simple with fibercoupled modulators, in contrast to bulk modulators needed for Ti:sapphire lasers. An in-line fiber amplifier can boost the power, such that a constant pulse energy is maintained regardless of the chosen pulse pattern. Significantly, these lasers offer excellent robustness at a fraction of the cost of a Ti:sapphire laser and occupy a fraction of the optical table space.Item Open Access High power K-band GaN on SiC CPW monolithic power amplifier(IEEE, 2014-10) Cengiz, Ömer; Şen, Özlem; Özbay, EkmelThis paper presents a high power amplifier at K-band (20.2-21.2 GHz). The AlGaN/GaN CPW MMIC amplifier is realized with 0.25 μm HEMT process on 2-inch semi-insulating SiC substrate. The amplifier has a small signal gain over 20 dB for Vds=15V and measured output power of over 31 dBm at 20.2 Ghz. PAE of the amplifier is around 22% for desired frequency band. Initial radiation hardness tests indicate a suitable stability of the technology in space. © 2014 European Microwave Association.Item Open Access Temperature-dependence of a GaN-based HEMT monolithic X-band low noise amplifier(IEEE, 2004-10) Schwindt, R. S.; Kumar, V.; Aktaş, Ozan; Lee, J.-W.; Adesida, I.The temperature-dependent performance of a fully monolithic AlGaN/GaN HEMT-based X-band low noise amplifier is reported. The circuit demonstrated a noise figure of 3.5 dB, gain of 7.5 dB, input return loss of -7.5 dB, and output return loss of -15 dB at 8.5 GHz at room temperature. The noise figure at 9.5 GHz increased from 2.5 dB at 43°C to 5.0 dB at 150°C. © 2004 IEEE.Item Open Access Time-and position-dependent modeling of high-power low-repetition-rate Er-Yb-fiber amplifier(IEEE, 2013) Pavlov, Ihor; Dülgergil, E.; Elahi, Parviz; İlday, F. ÖmerThere is rapid progress in the development of high-power fiber lasers due to their robust operation, low cost, high beam quality at high powers. There are various applications, such as laser sensing, LIDAR applications, processing of specific materials, which require robust and high-power pulsed laser sources at 1550 nm with high beam quality. Achievement of high peak power with low repetition rate is challenging due to well-known problems of strong nonlinear effects and amplified spontaneous emission (ASE) build-up between pulses. In order to reach highest efficiency, the design of each stage of amplification should be carefully optimized. Numerical modeling can be a great tool due to the large number of parameters involved [1]. To date, most modeling efforts of fiber amplification have assumed either a lumped gain model for pulse propagation or a distributed, position-dependent gain model for CW signal for computational simplicity. Here, we investigate both time- and position-dependent gain dynamics numerically, which are used to optimize experimental results. © 2013 IEEE.