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Artigos de revistas sobre o tema "Variable gain amplifiers"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 9 de fevereiro de 2022

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1

Bai, Chunfeng, Jianhui Wu e Xiaoying Deng. "A Review of CMOS Variable Gain Amplifiers and Programmable Gain Amplifiers". IETE Technical Review 36, n.º 5 (22 de agosto de 2018): 484–500. http://dx.doi.org/10.1080/02564602.2018.1507766.

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2

Liu, W., W. Liu e S. K. Wei. "CMOS exponential-control variable gain amplifiers". IEE Proceedings - Circuits, Devices and Systems 151, n.º 2 (2004): 83. http://dx.doi.org/10.1049/ip-cds:20040111.

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3

Borel, Andžej. "DEVELOPMENT AND INVESTIGATION OF INPUT AMPLIFIER FOR THE OSCILOSCOPE". Mokslas - Lietuvos ateitis 12 (20 de janeiro de 2020): 1–5. http://dx.doi.org/10.3846/mla.2020.11420.

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Digital oscilloscope’s structure has analog signal acquisition circuit, which transforms signal’s amplitude to fit ADC dynamic range. This circuit is commonly called oscilloscope’s vertical or front-end amplifier. Difficulty in designing front-end amplifiers in GHz range largely affects higher frequency range oscilloscope’s price. This work is focused on designing a front-end amplifier using discrete and openly sold components. We propose a design for attenuator, buffer, variable gain circuits. Amplifier’s prototype is designed. Main characteristics of the amplifier were measured. Measured bandwidth is 3 GHz. Amplifier’s gain and attenuation can support vertical scale sensitivity range from 10 mV/div to 1 V/div. Step response distortion is under 10 %. SMD and PTH relay model attenuators were evaluated. In this paper we review oscilloscope’s front-end purpose and structure. We review amplifiers design and provide the results of experimental measurements.

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4

DUONG, Q. H., C. W. KIM e S. G. LEE. "All CMOS Low-Power Wide-Gain Range Variable Gain Amplifiers". IEICE Transactions on Electronics E91-C, n.º 5 (1 de maio de 2008): 788–97. http://dx.doi.org/10.1093/ietele/e91-c.5.788.

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5

Huang, Yan-Yu, Wangmyong Woo, Hamhee Jeon, Chang-Ho Lee e J. Stevenson Kenney. "Compact Wideband Linear CMOS Variable Gain Amplifier for Analog-Predistortion Power Amplifiers". IEEE Transactions on Microwave Theory and Techniques 60, n.º 1 (janeiro de 2012): 68–76. http://dx.doi.org/10.1109/tmtt.2011.2175234.

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6

Ciubotaru, A. A. "A precision control circuit for variable-gain amplifiers". IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications 43, n.º 9 (1996): 779–82. http://dx.doi.org/10.1109/81.536747.

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7

Juang, C., S. F. Shiue, S. Y. Tsai e J. N. Yang. "Transimpedance amplifiers using three cascade variable inverter gain stages". Analog Integrated Circuits and Signal Processing 49, n.º 3 (11 de setembro de 2006): 299–302. http://dx.doi.org/10.1007/s10470-006-9706-0.

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8

Belousov, E. O., e A. G. Timoshenko. "Method for extending the bandwidth of variable gain amplifiers". Russian Microelectronics 43, n.º 7 (14 de novembro de 2014): 459–61. http://dx.doi.org/10.1134/s1063739714070026.

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9

Schindeler, Ryan, Daniel Cleveland e Keyvan Hashtrudi-Zaad. "Experimental evaluation of computer-controlled variable gain analog amplifiers". Analog Integrated Circuits and Signal Processing 86, n.º 3 (21 de janeiro de 2016): 449–58. http://dx.doi.org/10.1007/s10470-016-0690-8.

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10

Kong, Lingshan, Yong Chen, Haohong Yu, Chirn Chye Boon, Pui-In Mak e Rui P. Martins. "Wideband Variable-Gain Amplifiers Based on a Pseudo-Current-Steering Gain-Tuning Technique". IEEE Access 9 (2021): 35814–23. http://dx.doi.org/10.1109/access.2021.3062360.

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11

Schneider, A., e O. Werther. "Nonlinear Analysis of Noise in Current-Steering Variable Gain Amplifiers". IEEE Journal of Solid-State Circuits 39, n.º 2 (fevereiro de 2004): 290. http://dx.doi.org/10.1109/jssc.2003.821782.

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12

Petrzela, Jiri, e Roman Sotner. "Binary Memory Implemented by Using Variable Gain Amplifiers With Multipliers". IEEE Access 8 (2020): 197276–86. http://dx.doi.org/10.1109/access.2020.3034665.

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13

Godoy, Philip, e Joel L. Dawson. "Chopper Stabilization of Analog Multipliers, Variable Gain Amplifiers, and Mixers". IEEE Journal of Solid-State Circuits 43, n.º 10 (outubro de 2008): 2311–21. http://dx.doi.org/10.1109/jssc.2008.2004328.

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14

Kim, Chang-Woo. "Monolithic SiGe HBT Feedforward Variable Gain Amplifiers for 5 GHz Applications". ETRI Journal 28, n.º 3 (9 de junho de 2006): 386–88. http://dx.doi.org/10.4218/etrij.06.0205.0134.

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15

IIZUKA, K., M. KOUTANI, T. MITSUNAKA, H. KAWAMURA, S. TOYOYAMA, M. MIYAMOTO e A. MATSUZAWA. "RF Variable-Gain Amplifiers and AGC Loops for Digital TV Receivers". IEICE Transactions on Electronics E91-C, n.º 6 (1 de junho de 2008): 854–61. http://dx.doi.org/10.1093/ietele/e91-c.6.854.

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16

Bameri, H., H. Abdollahi e A. Hakimi. "A comprehensive, adjustable approach for linearizing and broadening the gain characteristic of variable gain amplifiers". Microelectronics Journal 45, n.º 8 (agosto de 2014): 1079–86. http://dx.doi.org/10.1016/j.mejo.2014.04.041.

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17

Lee, Samuel B. S., Hang Liu, Kiat Seng Yeo, Jer-Ming Chen e Xiaopeng Yu. "Design of Differential Variable-Gain Transimpedance Amplifier in 0.18 µm SiGe BiCMOS". Electronics 9, n.º 7 (27 de junho de 2020): 1058. http://dx.doi.org/10.3390/electronics9071058.

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This paper presents two new inductorless differential variable-gain transimpedance amplifiers (DVGTIA) with voltage bias controlled variable gain designed in TowerJazz’s 0.18 µm SiGe BiCMOS technology (using CMOS transistors only). Both consist of a modified differential cross-coupled regulated cascode preamplifier stage and a cascaded amplifier stage with bias-controlled gain-variation and third-order interleaving feedback. The designs have wide measured transimpedance gain ranges of 24.5–60.6 dBΩ and 27.8–62.8 dBΩ with bandwidth above 6.42 GHz and 5.22 GHz for DVGTIA designs 1 and 2 respectively. The core power consumptions are 30.7 mW and 27.5 mW from a 1.8 V supply and the input referred noise currents are 10.3 pA/√Hz and 21.7 pA/√Hz. The DVGTIA designs 1 and 2 have a dynamic range of 40.4 µA to 3 mA and 76.8 µA to 2.7 mA making both suitable for real photodetectors with an on-chip photodetector capacitive load of 250 fF. Both designs are compact with a core area of 100 µm × 85 µm.

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18

Snow, K. H., J. J. Komiak e D. A. Bates. "Segmented dual-gate MESFETs for variable gain and power amplifiers in GaAs MMIC". IEEE Transactions on Microwave Theory and Techniques 36, n.º 12 (dezembro de 1988): 1976–85. http://dx.doi.org/10.1109/22.17442.

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19

Kobayashi, K. W., A. K. Oki, D. K. Umemoto, S. K. Z. Claxton e D. C. Streit. "Monolithic GaAs HBT p-i-n diode variable gain amplifiers, attenuators, and switches". IEEE Transactions on Microwave Theory and Techniques 41, n.º 12 (1993): 2295–302. http://dx.doi.org/10.1109/22.260720.

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20

del Pino, J., Sunil L. Khemchandani, D. Galante-Sempere e C. Luján-Martínez. "A Compact Size Wideband RF-VGA Based on Second Generation Controlled Current Conveyors". Electronics 9, n.º 10 (30 de setembro de 2020): 1600. http://dx.doi.org/10.3390/electronics9101600.

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This paper presents a methodology to design a wideband radio frequency variable gain amplifier (RF-VGA) in a low-cost SiGe BiCMOS 0.35 μm process. The circuit uses two Class A amplifiers based on second-generation controlled current conveyors (CCCII). The main feature of this circuit is the wideband input match along with a reduced NF (5.5–9.6 dB) and, to the authors’ knowledge, the lowest die footprint reported (62 × 44 μm2 area). The implementation of the RF-VGA based on CCCII allows a wideband input match without the need of passive elements. Due to the nature of the circuit, when the gain is increased, the power consumption is reduced. The architecture is suitable for designing wideband, low-power, and low-noise amplifiers. The proposed design achieves a tunable gain of 6.7–18 dB and a power consumption of 1.7 mA with a ±1.5 V DC supply. At maximum gain, the proposed RF-VGA covers from DC up to 1 GHz and can find application in software design radios (SDRs), the low frequency medical implant communication system (MICS) or industrial, scientific, and medical (ISM) bands.

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21

Zvorykin, V. D., N. V. Didenko, A. A. Ionin, I. V. Kholin, A. V. Konyashchenko, O. N. Krokhin, A. O. Levchenko et al. "GARPUN-MTW: A hybrid Ti:Sapphire/KrF laser facility for simultaneous amplification of subpicosecond/nanosecond pulses relevant to fast-ignition ICF concept". Laser and Particle Beams 25, n.º 3 (20 de julho de 2007): 435–51. http://dx.doi.org/10.1017/s0263034607000559.

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The first stage of the petawatt excimer laser project started at the P.N. Lebedev Physical Institute, implements a development of multiterawatt hybrid GARPUN-MTW laser facility for generation of ultra-high intensity subpicosecond ultraviolet (UV) laser pulses. Under this project, a multi-stage e-beam-pumped 100-J, 100-ns GARPUN KrF laser was upgraded with a femtosecond Ti:Sapphire front-end, to produce combined subpicosecond/nanosecond laser pulses with variable time delay. Attractive possibility to amplify simultaneously short and long pulses in the same large-scale KrF amplifiers is analyzed with regard to the fast-ignition, inertial confinement fusion problem. Detailed description of hybrid laser system is presented with synchronized KrF and Ti:Sapphire master oscillators. Based on gain and absorption measurements at GARPUN amplifier and numerical simulations with a quasi-stationary code, we are predicting that 1.6 J can be obtained in a short pulse at hybrid GARPUN-MTW Ti:Sapphire/KrF laser facility, combined with several tens of joules in nanosecond pulse. Amplified spontaneous emission, which is responsible for the pre-pulse formation on a target, was also investigated: its acceptable level can be provided by properly choosing staged gain or loading the amplifiers by quasi-steady laser radiation. Fluorescence and transient absorption spectra of Ar/Kr/F2 mixtures conventionally used in KrF amplifiers were recorded to find out the possibility for femtosecond pulse amplification at the broadband Kr2F (42Γ → 1,2 2Γ) transition, which benefits in 100 times higher saturation energy density than for KrF (B → X) transition.

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22

Abdelfattah, K. M., e A. M. Soliman. "Variable gain amplifiers based on a new approximation method to realize the exponential function". IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications 49, n.º 9 (setembro de 2002): 1348–54. http://dx.doi.org/10.1109/tcsi.2002.802365.

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23

Arigong, Bayaner, Hualiang Zhang, Sungyong Jung e Hyoungsoo Kim. "A feed-forward equalizer with winner-take-all variable gain amplifiers for backplane channels". Microwave and Optical Technology Letters 55, n.º 11 (26 de agosto de 2013): 2666–70. http://dx.doi.org/10.1002/mop.27924.

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24

Liu, Hang, Xi Zhu, Chirn Chye Boon e Xiaofeng He. "Cell-Based Variable-Gain Amplifiers With Accurate dB-Linear Characteristic in 0.18 µm CMOS Technology". IEEE Journal of Solid-State Circuits 50, n.º 2 (fevereiro de 2015): 586–96. http://dx.doi.org/10.1109/jssc.2014.2368132.

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25

Langhammer, Lukas, Roman Sotner, Jan Dvorak, Jan Jerabek e Peter A. Ushakov. "Novel Reconnection-Less Reconfigurable Filter Design Based on Unknown Nodal Voltages Method and Its Fractional-Order Counterpart". Elektronika ir Elektrotechnika 25, n.º 3 (25 de junho de 2019): 34–38. http://dx.doi.org/10.5755/j01.eie.25.3.23673.

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A novel solution of reconnection-less electronically reconfigurable filter is introduced in the paper. The filter is designed based on unknown nodal voltages method (MUNV) using operational transconductance amplifiers (OTAs) and variable gain amplifier (VGA). The structure can provide all-pass, band-stop, high-pass 2nd order functions, high-pass function of the 1st order and direct transfer from the same topology without requirement of manual reconnection. The proposed structure also offers the electronic control of the pole frequency. Moreover, fractional-order design of the proposed filter is also provided. The behaviour is verified by simulations using Cadence IC6 (spectre) software.

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26

Gu, Cheng Jie, Xiang Ning Fan, Kuan Bao e Zai Jun Hua. "Design of a Reconfigurable Mixer for Multi-Mode Multi-Standard Receivers". Applied Mechanics and Materials 618 (agosto de 2014): 553–57. http://dx.doi.org/10.4028/www.scientific.net/amm.618.553.

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This paper reports a reconfigurable wideband passive mixer for direct conversion multimode multi-standard receivers. Different from the traditional current-commutating passive mixers, transconductor stage of this design is variable. And the TIA stage is a second-order low-pass transimpedance amplifiers based on Tow-Thomas biquad topology, working as a current mode filter. The mixer is controlled by a 4-bit control word to realize the flexible gain and variable intermediate frequency bandwidth. Other characteristics such as power consumption, NF, and linearity is also reconfigurable according to different communication standard. Circuit is implementing in 0.18μm CMOS technology. Post-simulation results show that, with the radio frequency ranges from 700 MHz to 2.6 GHz, it provides four voltage conversion gains (10/16/22/28dB) and three-3 dB intermediate frequency bandwidth (5/7.5/10MHz). Under the maximum gain, the double sideband NF of the mixer is 8.4 dB. And under the minimum gain, IIP3 is 13 dBm. The chip occupies an area of 0.248 mm2 and drains a current of 8.5mA from a 1.8 V supply when the mixer has highest gain.

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27

Zeb, Muhammad, Muhammad Tahir, Fida Muhammad, Suhana Mohd Said, Mohd Faizul Mohd Sabri, Mahidur R. Sarker, Sawal Hamid Md Ali e Fazal Wahab. "Amplified Spontaneous Emission and Optical Gain in Organic Single Crystal Quinquethiophene". Crystals 9, n.º 12 (21 de novembro de 2019): 609. http://dx.doi.org/10.3390/cryst9120609.

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In this paper, we report optical characteristics of an organic single crystal oligomer 5,5⁗-diphenyl-2,2′:5′,2″:5″,2‴:5‴,2⁗-quinquethiophene (P5T). P5T crystal is a thiophene/phenylene co-oligomer that possesses better charge mobility as well as photoluminescence quantum efficiency (PLQE) as compared to other organic materials. Stimulated emission in P5T is investigated via amplified spontaneous emission (ASE) measurements within broad pump energies ranging from 35.26 to 163.34 µJ/cm2. An Nd-YAG femtosecond-tunable pulsed laser is used as a pump energy source for the ASE measurements of P5T crystals at an excitation wavelength of 445 nm. The ASE spectra exhibit optical amplification in P5T crystals at a 625 nm peak wavelength with a lower threshold energy density (Eth) ≈ 52.64 μJ/cm2. P5T also demonstrates higher optical gain with a value of 72 cm−1, that is calculated by using the variable stripe-length method. The value of PLQE is measured to be 68.24% for P5T. This study proposes potential applications of P5T single crystals in organic solid state lasers, photodetectors, and optical amplifiers.

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28

RUNGE, K., P. J. ZAMPARDI, R. L. PIERSON, R. YU, P. B. THOMAS, S. M. BECCUE e K. C. WANG. "AlGaAs/GaAs HBT CIRCUITS FOR OPTICAL TDM COMMUNICATIONS". International Journal of High Speed Electronics and Systems 09, n.º 02 (junho de 1998): 473–503. http://dx.doi.org/10.1142/s012915649800021x.

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We describe experimental ultra-high-speed HBT circuits for lightwave communications applications. High speed circuits such as multiplexer/demultiplexers, variable gain amplifiers, (VGAs), and transimpedance amplifiers operating at high bit rates (>30 Gb/s) are required for the realization of high-performance lightwave systems using TDM or WDM. We have demonstrated 40 Gb/s 4:1 multiplexer, >30 Gb/s 1:4 demultiplexers, DC-26 GHz VGAs, DC-25 GHz transimpedance amplifiers, 30 Gb/s data and clock regenerators, 40 Gb/s differentiate-and-rectify timing recovery circuits, and 40 Gb/s delay-and-multiply timing recovery circuits, for use in such systems using a manufacturable hybrid digital/microwave HBT process.

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29

Han, Jingyu, Yu Jiang, Guiliang Guo e Xu Cheng. "A Reconfigurable Analog Baseband Circuitry for LFMCW RADAR Receivers in 130-nm SiGe BiCMOS Process". Electronics 9, n.º 5 (18 de maio de 2020): 831. http://dx.doi.org/10.3390/electronics9050831.

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A highly reconfigurable open-loop analog baseband circuitry with programmable gain, bandwidth and filter order are proposed for integrated linear frequency modulated continuous wave (LFMCW) radar receivers in this paper. This analog baseband chain allocates noise, gain and channel selection specifications to different stages, for the sake of noise and linearity tradeoffs, by introducing a multi-stage open-loop cascaded amplifier/filter topology. The topology includes a course gain tuning pre-amplifier, a folded Gilbert variable gain amplifier (VGA) with a symmetrical dB-linear voltage generator and a 10-bit R-2R DAC for fine gain tuning, a level shifter, a programmable Gm-C low pass filter, a DC offset cancellation circuit, two fixed gain amplifiers with bandwidth extension and a novel buffer amplifier with active peaking for testing purposes. The noise figure is reduced with the help of a low noise pre-amplifier stage, while the linearity is enhanced with a power-efficient buffer and a novel high linearity Gm-C filter. Specifically, the Gm-C filter improves its linearity specification with no increase in power consumption, thanks to an alteration of the trans-conductor/capacitor connection style, instead of pursuing high linearity but power-hungry class-AB trans-conductors. In addition, the logarithmic bandwidth tuning technique is adopted for capacitor array size minimization. The linear-in-dB and DAC gain control topology facilitates the analog baseband gain tuning accuracy and stability, which also provides an efficient access to digital baseband automatic gain control. The analog baseband chip is fabricated using 130-nm SiGe BiCMOS technology. With a power consumption of 5.9~8.8 mW, the implemented circuit achieves a tunable gain range of −30~27 dB (DAC linear gain step guaranteed), a programmable −3 dB bandwidth of 18/19/20/21/22/23/24/25 MHz, a filter order of 3/6 and a gain resolution of better than 0.07 dB.

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30

Kumar, Umesh, e P. Bhushan Mital. "Design, Fabrication, and Comparative Study of Electronically Tunable Active Filters". Active and Passive Electronic Components 18, n.º 2 (1995): 73–109. http://dx.doi.org/10.1155/1995/78209.

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The Kerwin-Huelsman Newcomb (KHN) biquad is the natural choice for use as a ‘universal’ filter building block out of the several existing 3-amplifier biquadratic filter sections based on the two integrator loop or state variable realization of 2nd order systems. A modified version of the KHN biquad, which is electronically tunable almost linearly over a decade range of center frequency, is presented. For electronic tunability, instead of the direct use of a FET as a voltage variable resistance to control the time constants of the integrators, a novel approach of using voltage-controlled variable-gain amplifiers at the inputs of both the integrators and one immediately after the input signal has been suggested. The circuit is suitable for use as a tunable universal filtering module and can be easily digitally programmed.Comparative treatment of general tuning methods of active filters, and some methods of electronic tuning of active filters are discussed. A brief description of tuning algorithms of active filters is also given.

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31

Mayer, U., F. Ellinger e R. Eickhoff. "Analysis and reduction of phase variations of variable gain amplifiers verified by CMOS implementation at C-band". IET Circuits, Devices & Systems 4, n.º 5 (2010): 433. http://dx.doi.org/10.1049/iet-cds.2009.0299.

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Nam, Hyosung, Taejoo Sim e Junghyun Kim. "A 2.4 GHz 20 W 8-channel RF Source Module with Solid-State Power Amplifiers for Plasma Generators". Electronics 9, n.º 9 (26 de agosto de 2020): 1378. http://dx.doi.org/10.3390/electronics9091378.

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This paper presents a novel multi-channel type RF source module with solid-state power amplifiers for plasma generators. The proposed module is consisted of a DC control part, RF source generation part, and power amplification part. A 2-stage power amplifier (PA) is combined with a gallium arsenide hetero bipolar transistor (GaAs HBT) as a drive PA and a gallium nitride high electron mobility transistor (GaN HEMT) as a main PA, respectively. By employing 8 channels, the proposed module secures better area coverage on the wafer during semiconductor processes such as chemical vapor deposition (CVD), etching and so on. Additionally, each channel can be maintained at a constant output power because they have a gain factor tunable by a variable gain amplifier (VGA). For that reason, it is possible to have uniform plasma density on the wafer. The operating sequence is controllable by an external DC control port. Moreover, copper–tungsten (CuW) heat spreaders were applied to prevent RF performance degradation from heat generated by the high power amplifier (HPA), and a water jacket was implemented at the bottom of the power amplification part for liquid cooling. Drawing upon the measurement results, the output power at each channel was over 43 dBm (20 W) and the drain efficiency was more than 50% at 2.4 GHz.

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SOLIMAN, EMAN A., e SOLIMAN A. MAHMOUD. "THE DIFFERENTIAL DIFFERENCE OPERATIONAL FLOATING AMPLIFIER: NEW CMOS REALIZATIONS AND APPLICATIONS". Journal of Circuits, Systems and Computers 18, n.º 07 (novembro de 2009): 1287–308. http://dx.doi.org/10.1142/s0218126609005666.

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This paper presents different novel CMOS realizations for the differential difference operational floating amplifier (DDOFA). The DDOFA was first introduced in Ref. 1 and was used to realize different analog circuits like integrators, filters and variable gain amplifiers. New CMOS realizations for the DDOFA are introduced in this literature. Furthermore the DDOFA is modified to realize a fully differential current conveyor (FDCC). Novel CMOS realizations of the FDCC are presented. The FDCC is used to realize second-order band pass–low-pass filter. Performance comparisons between the different realizations of the DDOFA and FDCC are given in this literature. PSPICE simulations of the overall proposed circuits are given using 0.25 μm CMOS Technology from TMSC MOSIS model and dual supply voltages of ±1.5 V.

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Moriyama, Takuro, e Daisuke Kurabayashi. "Adaptive Control Using an Oscillator Network with Capacitive Couplers". Journal of Advanced Computational Intelligence and Intelligent Informatics 15, n.º 6 (20 de agosto de 2011): 632–38. http://dx.doi.org/10.20965/jaciii.2011.p0632.

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We focus on the oscillatory aspects of neural components and their roles in neural system functionality such as adaptability. This study provides an implementation of adaptive control by using a network system consisting of oscillators and capacitive couplers. The functionality of oscillators alone is fairly limited, but capacitive couplers change interaction between oscillators, enabling logical operations, absolute function, gain variable amplifiers, and adaptive control. We provide basic functional networks of oscillators and capacitive couplers and demonstrate adaptive control implementation based on these functions.

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35

Hyun, Eugin, Young-Seok Jin e Jong-Hun Lee. "Design and Implementation of 24 GHz Multichannel FMCW Surveillance Radar with a Software-Reconfigurable Baseband". Journal of Sensors 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/3148237.

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We designed and developed a 24 GHz surveillance FMCW (Frequency Modulated Continuous Wave) radar with a software-reconfigurable baseband. The developed radar system consists of transceiver, two selectable transmit antennas, eight parallel receive antennas, and a back-end module for data logging and to control the transceiver. The architecture of the developed radar system can support various waveforms, gain control of receive amplifiers, and allow the selection of two transmit antennas. To do this, we implemented the transceiver using a frequency synthesizer device and a two-step VGA (Variable Gain Amplifier) along with switch-controlled transmit antennas. To support high speed implementation features along with good flexibility, we developed a back-end module based on a FPGA (Field Programmable Gate Array) with a parallel architecture for the real-time data logging of the beat signals received from a multichannel 24 GHz transceiver. To verify the feasibility of the developed radar system, signal processing algorithms were implemented on a host PC. All measurements were carried out in an anechoic chamber to extract a 3D range-Doppler-angle map and target detections. We expect that the developed software-reconfigurable radar system will be useful in various surveillance applications.

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Gaspar, Imre, Yanxun V. Yu, Sean L. Cotton, Dae-Hwan Kim, Anne Ephrussi e Michael A. Welte. "Klar ensures thermal robustness of oskar localization by restraining RNP motility". Journal of Cell Biology 206, n.º 2 (21 de julho de 2014): 199–215. http://dx.doi.org/10.1083/jcb.201310010.

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Communication usually applies feedback loop–based filters and amplifiers to ensure undistorted delivery of messages. Such an amplifier acts during Drosophila melanogaster midoogenesis, when oskar messenger ribonucleic acid (mRNA) anchoring depends on its own locally translated protein product. We find that the motor regulator Klar β mediates a gain-control process that prevents saturation-based distortions in this positive feedback loop. We demonstrate that, like oskar mRNA, Klar β localizes to the posterior pole of oocytes in a kinesin-1–dependent manner. By live imaging and semiquantitative fluorescent in situ hybridization, we show that Klar β restrains oskar ribonucleoprotein motility and decreases the posterior-ward translocation of oskar mRNA, thereby adapting the rate of oskar delivery to the output of the anchoring machinery. This negative regulatory effect of Klar is particularly important for overriding temperature-induced changes in motility. We conclude that by preventing defects in oskar anchoring, this mechanism contributes to the developmental robustness of a poikilothermic organism living in a variable temperature environment.

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Nguyen Thi, Bao My, Van Sy Nguyen, Van Tien Vu, Quang Tuan Ho, Thuy Mai Nguyen Thi, Ngoc Thiem Le, Thi Anh Vo e Manh Hung Nguyen. "Equipment for measuring the characteristics of X-ray". Nuclear Science and Technology 6, n.º 2 (24 de setembro de 2021): 39–46. http://dx.doi.org/10.53747/jnst.v6i2.155.

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X-ray measurement equipment is designed which utilizes a pair of photodiode detectors. The equipment is designed which utilizes a pair of photodiode detectors units which receive X-rays through filters with different attenuation coefficients for X-rays. The photodiode detector units preferably includes two pairs of photodiode detectors arranged symmetrically in four quadrants with the diodes in each detector unit in diagonally opposite quadrants. The outputs of the detector units are passed to variable gain amplifiers, gains of which are adjusted to bring the output voltages within a desired range, and the outputs of the amplifiers are integrated by integrators. After a selected period of time, the integration is stopped and the output voltages of the integrators are held and transmitted to an analog-to-digital converter. The ratio of the two output signals from a pair of photodiode detectors represents the kVp value of the X-ray machine and another pair of photodiode detectors used to measure the relative current in milliamps (mA) and exposure time of the x-ray unit.In this study, the equipment have been made for measuring the characteristics of X-Ray with an accuracy of kVp (kV), I (mA) is 5% and the 2% T.

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Kim, Jungah, Yongho Lee, Shinil Chang e Hyunchol Shin. "Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability". Electronics 9, n.º 3 (17 de março de 2020): 494. http://dx.doi.org/10.3390/electronics9030494.

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We present a low-power CMOS active-resistance-capacitance (active-RC) complex bandpass filter (BPF) with tunable gain, bandwidth, center frequency, quality factor, and passband flatness for Bluetooth applications. A transfer function analysis for a cross-coupled Tow-Thomas biquad structure is presented to prove that the flatness profile of the passband gain can be effectively controlled by independently tuning two cross-coupling resistors. The proposed biquad-based complex BPF was employed to realize a fourth-order baseband analog processor for a low intermediate frequency (low-IF) RF receiver. The baseband analog processor was composed of two complex biquad filters and three first-order variable-gain amplifiers. It was fabricated in a 65-nm RF CMOS and achieved wide tuning capabilities, such as a gain of −15.6 to 50.6 dB, a bandwidth of 1.4–3.9 MHz, a center frequency of 1.5–4.1 MHz, and a passband flatness of −1 to 1 dB. It also achieved an image rejection ratio of 40.3–53.3 dB across the entire gain tuning range. It consumed 1.4 mA from a 1 V supply and occupied an area of 0.19 mm2 on the silicon substrate. The implementation results prove that the proposed complex BPF was able to effectively enhance the signal processing performances through the flexible and wide-range tunability of the passband flatness, as well as that of the gain, bandwidth, center frequency, and quality factor.

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Nguyen, Van-Viet, Hyohyun Nam, Young Choe, Bok-Hyung Lee e Jung-Dong Park. "An X-band Bi-Directional Transmit/Receive Module for a Phased Array System in 65-nm CMOS". Sensors 18, n.º 8 (6 de agosto de 2018): 2569. http://dx.doi.org/10.3390/s18082569.

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We present an X-band bi-directional transmit/receive module (TRM) for a phased array system utilized in radar-based sensor systems. The proposed module, comprising a 6-bit phase shifter, a 6-bit digital step attenuator, and bi-directional gain amplifiers, is fabricated using 65-nm CMOS technology. By constructing passive networks in the phase-shifter and the variable attenuator, the implemented TRM provides amplitude and phase control with 360° phase coverage and 5.625° as the minimum step size while the attenuation range varies from 0 to 31.5 dB with a step size of 0.5 dB. The fabricated T/R module in all of the phase shift states had RMS phase errors of less than 4° and an RMS amplitude error of less than 0.93 dB at 9–11 GHz. The output 1dB gain compression point (OP1dB) of the chip was 5.13 dBm at 10 GHz. The circuit occupies 3.92 × 2.44 mm2 of the chip area and consumes 170 mW of DC power.

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40

Wheeler, Diek W., Paul H. M. Kullmann e John P. Horn. "Estimating Use-Dependent Synaptic Gain in Autonomic Ganglia by Computational Simulation and Dynamic-Clamp Analysis". Journal of Neurophysiology 92, n.º 5 (novembro de 2004): 2659–71. http://dx.doi.org/10.1152/jn.00470.2004.

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Biological gain mechanisms regulate the sensitivity and dynamics of signaling pathways at the systemic, cellular, and molecular levels. In the sympathetic nervous system, gain in sensory-motor feedback loops is essential for homeostatic regulation of blood pressure and body temperature. This study shows how synaptic convergence and plasticity can interact to generate synaptic gain in autonomic ganglia and thereby enhance homeostatic control. Using a conductance-based computational model of an idealized sympathetic neuron, we simulated the postganglionic response to noisy patterns of presynaptic activity and found that a threefold amplification in postsynaptic spike output can arise in ganglia, depending on the number and strength of nicotinic synapses, the presynaptic firing rate, the extent of presynaptic facilitation, and the expression of muscarinic and peptidergic excitation. The simulations also showed that postsynaptic refractory periods serve to limit synaptic gain and alter postsynaptic spike timing. Synaptic gain was measured by stimulating dissociated bullfrog sympathetic neurons with 1–10 virtual synapses using a dynamic clamp. As in simulations, the threshold synaptic conductance for nicotinic excitation of firing was typically 10–15 nS, and synaptic gain increased with higher levels of nicotinic convergence. Unlike the model, gain in neurons sometimes declined during stimulation. This postsynaptic effect was partially blocked by 10 μM Cd2+, which inhibits voltage-dependent calcium currents. These results support a general model in which the circuit variations observed in parasympathetic and sympathetic ganglia, as well as other neural relays, can enable functional subsets of neurons to behave either as 1:1 relays, variable amplifiers, or switches.

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Evseev, Vladimir, Mikhail Ivlev, Elena Lupanova, Sergey Nikulin, Vitaliy Petrov e Andrey Terentyev. "Automation of S-parameters measurements of high-power microwave transistors in a contact device with tunable strip matching circuits". ITM Web of Conferences 30 (2019): 11002. http://dx.doi.org/10.1051/itmconf/20193011002.

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In the practice by microwave power transistor amplifiers developing, the variable load method is usually used to determine the impedances of matching circuits in the complex conjugate matching mode. This solution involves the use of expensive equipment - coaxial impedance tuners and contact devices for mounting transistors in low impedance strip lines. An even more complicated and expensive way is the concept of X- parameters, based on the use of unique measuring equipment - a non-linear vector network analyzer, and a simulator for non-linear circuits design. The article proposes an alternative solution adapted to the operation of the transistor in real conditions and allowing to design the output stages of microwave power amplifiers using analysis and optimization of linear electrical circuits. The essence of the proposed solution is to automate the measurement of non-linear S-parameters of high-power microwave transistors in a contact device with tunable strip matching circuits for various DC supply voltage, frequency and input power mode in case of continuous or pulse input signal. The nonlinear S-parameters of the contact device are measured using the method of spatially remote variable load in the frequency range, in which the line conditioning and the maximum output power are achieved. The minimum of the reflected wave amplitude and the maximum gain are reached using movable strip matching transformers. The S-parameters measured in the coaxial line are automatically recalculated to the physical boundaries of the transistor by registering the positions of the input and output strip transformers.

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Gupta, Ritesh, Servin Rathi, Ravneet Kaur, Mridula Gupta e R. S. Gupta. "T-gate geometric (solution for submicrometer gate length) HEMT: Physical analysis, modeling and implementation as parasitic elements and its usage as dual gate for variable gain amplifiers". Superlattices and Microstructures 45, n.º 3 (março de 2009): 105–16. http://dx.doi.org/10.1016/j.spmi.2008.12.032.

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Alkhorshid, Daniel Rostami, Seyyedeh Fatemeh Molaeezadeh e Mikaeil Rostami Alkhorshid. "Analysis: Electroencephalography Acquisition System: Analog Design". Biomedical Instrumentation & Technology 54, n.º 5 (1 de setembro de 2020): 346–51. http://dx.doi.org/10.2345/0899-8205-54.5.346.

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Abstract Electroencephalography (EEG) is a sensitive and weak biosignal that varies from person to person. It is easily affected by noise and artifacts. Hence, maintaining the signal integrity to design an EEG acquisition system is crucial. This article proposes an analog design for acquiring EEG signals. The proposed design consists of eight blocks: (1) a radio-frequency interference filter and electro-static discharge protection, (2) a preamplifier and second-order high-pass filter with feedback topology and an unblocking mechanism, (3) a driven right leg circuit, (4) two-stage main and variable amplifiers, (5) an eight-order anti-aliasing filter, (6) a six-order 50-Hz notch filter (optional), (7) an opto-isolator circuit, and (8) an isolated power supply. The maximum gain of the design is approximately 94 dB, and its bandwidth ranges from approximately 0.18 to 120 Hz. The depth of the 50-Hz notch filter is −35 dB. Using this filter is optional because it causes EEG integrity problems in frequencies ranging from 40 to 60 Hz.

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Zhang, Jing Zhi. "A 520MHz Wideband Variable Gain Amplifier". Applied Mechanics and Materials 556-562 (maio de 2014): 1564–67. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.1564.

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The design and realization of a wideband variable gain amplifier for RF system is presented. The cascade of LNA and controllable attenuation makes the design have a 0-90dB gain adjustment range. Special care is devoted to the solution of typical problems encountered in the design of the amplifier, such as signal shielding and power supply decoupling. The amplifier uses passive amplitude-frequency equalization, 0.1-460MHz band variation is less than 1dB, the 3dB bandwidth is up to 520MHz. The noise characteristic is low, the total input referred noise is less than 15.5nV⁄√¯Hz.

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45

Balteanu, F., e M. Cloutier. "Charge-pump controlled variable gain amplifier". Electronics Letters 34, n.º 9 (1998): 838. http://dx.doi.org/10.1049/el:19980644.

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Asgari, Vahid, e Leonid Belostotski. "Wideband 28-nm CMOS Variable-Gain Amplifier". IEEE Transactions on Circuits and Systems I: Regular Papers 67, n.º 1 (janeiro de 2020): 37–47. http://dx.doi.org/10.1109/tcsi.2019.2942492.

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Chaudhry, Q., R. Alidio, G. Sakamoto e T. Cisco. "A SiGe MMIC variable gain cascode amplifier". IEEE Microwave and Wireless Components Letters 12, n.º 11 (novembro de 2002): 424–25. http://dx.doi.org/10.1109/lmwc.2002.805533.

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Floc'h, J. M., e L. Desclos. "Variable gain amplifier with traveling wave structure". Microwave and Optical Technology Letters 7, n.º 12 (20 de agosto de 1994): 539–42. http://dx.doi.org/10.1002/mop.4650071203.

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El-Gabaly, A. M., e C. E. Saavedra. "Wideband variable gain amplifier with noise cancellation". Electronics Letters 47, n.º 2 (2011): 116. http://dx.doi.org/10.1049/el.2010.3226.

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Thanachayanont, Apinunt. "Low-voltage compact CMOS variable gain amplifier". AEU - International Journal of Electronics and Communications 62, n.º 6 (junho de 2008): 413–20. http://dx.doi.org/10.1016/j.aeue.2007.06.002.

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