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Journal articles on the topic 'I/Q modulator impairments'

Author: Grafiati

Published: 8 June 2022

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1

Anttila, Lauri, Peter Händel, Olli Mylläri, and Mikko Valkama. "Recursive learning-based joint digital predistorter for power amplifier and I/Q modulator impairments." International Journal of Microwave and Wireless Technologies 2, no. 2 (April 2010): 173–82. http://dx.doi.org/10.1017/s1759078710000280.

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The main implementation impairments degrading the performance of direct-conversion radio transmitters are in-phase/quadrature (I/Q) mismatch, local oscillator (LO) leakage, and power amplifier (PA) nonlinear distortion. In this article, we propose a recursive least-squares-based learning algorithm for joint digital predistortion (PD) of frequency-dependent PA and I/Q modulator impairments. The predistorter is composed of a parallel connection of two parallel Hammerstein (PH) predistorters and an LO leakage compensator, yielding a predistorter which as a whole is fully linear in the parameters. In the parameter estimation stage, proper feedback signal from the transmitter radio frequency (RF) stage back to the digital parts is deployed, combined with the indirect learning architecture and recursive least-squares training. The proposed structure is one of the first techniques to explicitly consider the joint estimation and mitigation of frequency-dependent PA and I/Q modulator impairments. Extensive simulation and measurement analysis is carried out to verify the operation and efficiency of the proposed PD technique. In general, the obtained results demonstrate linearization and I/Q modulator calibration performance clearly exceeding the performance of current state-of-the-art reference techniques.

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2

Anttila, Lauri, Peter Handel, and Mikko Valkama. "Joint Mitigation of Power Amplifier and I/Q Modulator Impairments in Broadband Direct-Conversion Transmitters." IEEE Transactions on Microwave Theory and Techniques 58, no. 4 (April 2010): 730–39. http://dx.doi.org/10.1109/tmtt.2010.2041579.

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3

Anastasijevic, Ana, Duska Coja, Natasa Neskovic, Aleksandar Neskovic, and Djuradj Budimir. "Joint power amplifier and I/Q modulator impairments modelling and compensation for LTE transmitters using artificial neural networks." AEU - International Journal of Electronics and Communications 69, no. 2 (February 2015): 529–38. http://dx.doi.org/10.1016/j.aeue.2014.11.005.

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4

Tyagi, Rishita. "Simulation and Performance Analysis of RoF System Using Fiber Impairments." International Journal for Research in Applied Science and Engineering Technology 10, no. 5 (May 31, 2022): 2055–61. http://dx.doi.org/10.22214/ijraset.2022.42759.

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Abstract: A Radio over Fiber (RoF) system has a unique feature of containing both a fiber optic link and a free space radio path. Fiber based wireless access facilitates high-capacity multimedia services in a real-time basis. In this research paper, the RoF system is simulated in the presence of fiber impairments, namely, Polarization Mode Dispersion (PMD) and Cross Phase Modulation (XPM) and Four-Wave Mixing (FWM) with the help of OptiSystem simulation tool. The variations in Quality factor (Q factor) and Bit Error Rate (BER) with respect to wavelength of 1552 nm and bit rates of 10 Gb/s of input signal is analyzed in the presence of the linear and non-linear impairments of the fiber. Keywords: Radio over Fiber (RoF), Polarization Mode Dispersion (PMD), Cross Phase Modulation (XPM), Four-Wave Mixing (FWM), OptiSystem, Bit Error Rate (BER), Q factor.

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5

Wu, Yibo, Ulf Gustavsson, Alexandre Graell I. Amat, and Henk Wymeersch. "Low Complexity Joint Impairment Mitigation of I/Q Modulator and PA Using Neural Networks." IEEE Journal on Selected Areas in Communications 40, no. 1 (January 2022): 54–64. http://dx.doi.org/10.1109/jsac.2021.3126024.

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6

Muhammad, Fazal, Farman Ali, Usman Habib, Muhammad Usman, Imran Khan, and Sunghwan Kim. "Time Domain Equalization and Digital Back-Propagation Method-Based Receiver for Fiber Optic Communication Systems." International Journal of Optics 2020 (February 12, 2020): 1–13. http://dx.doi.org/10.1155/2020/3146374.

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Fiber optic communication systems (FOCSs) have attained a lot of attention by revolutionizing the telecommunication industry and offering new possibilities with the technical advancements in state-of-the-art high speed digital electronics. Advanced modulation formats make use of the phase, amplitude, and polarization of the optical signals at the same time to provide high spectral efficiency as compared with 1 bit/s/Hz for the intensity modulation direct detection system (IMDD), but are highly prone to transmission impairments. Thus, the effects that add up to the optical fiber impairments such as optical fiber chromatic dispersion (OFCD), polarization model dispersion (PMD), and phase offset and noise (POaN) need to be addressed at the receiver side. The development of components and algorithms to minimize these effects in next generation FOCSs with 100 Gbps data rate and beyond with long-haul transmission is still a challenging issue. In this paper, digital signal processing- (DSP-) assisted dispersion and nonlinear compensation techniques are presented to compensate for physical layer impairments including OFCD, PMD, and POaN. The simulations are performed considering Dual Polarization- (DP-) QPSK modulation format to achieve two-fold data rate to achieve spectral efficiency of 3.28 bits/s/Hz by making use of the polarization diversity and system performance is investigated in terms of bit error rate (BER), constellation diagrams, and quality factor (Q-factor) for different values of optical signal-to-noise ratio (OSNR), launch power (PL), and fiber length.

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7

Trombley, Paul Q. "Selective Modulation of GABAA Receptors by Aluminum." Journal of Neurophysiology 80, no. 2 (August 1, 1998): 755–61. http://dx.doi.org/10.1152/jn.1998.80.2.755.

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Trombley, Paul Q. Selective modulation of GABAA receptors by aluminum. J. Neurophysiol. 80: 755–761, 1998. Aluminum has been implicated in several neurodegenerative conditions including Alzheimer's disease. Because the mammalian olfactory system has an unusual capacity for the uptake and transneuronal spread of inhaled substances such as aluminum, whole cell recording techniques were used to examine the actions of aluminum on basic membrane properties and amino acid receptors on rat olfactory bulb mitral/tufted (M/T) neurons in culture. Aluminum had little direct effects on M/T neurons. Aluminum (100 μM) did not evoke a membrane current or alter action-potential shape or duration. Aluminum also had no marked effects on the family of voltage-gated membrane currents evoked by a series of 10-mV, 50-ms depolarizing steps. However, aluminum dramatically potentiated the current evoked by 30 μM γ-aminobutyric acid (GABA) at concentrations <100 μM. Conversely, higher concentrations of aluminum blocked the GABA-evoked current. The effects of aluminum on GABA-evoked currents were not voltage dependent. Aluminum (100 μM) equally potentiated both inward currents at −30 mV and outward currents at + 30 mV. At 300 μM, aluminum blocked both inward and outward currents to a similar extent. In some neurons, aluminum only blocked the current and potentiation was not observed. The biphasic action of aluminum on GABA-evoked currents suggests separate binding sites: a high-affinity potentiating site and a low-affinity inhibiting site. Despite its effects on GABA-evoked currents, aluminum did not alter membrane currents evoked by glutamate, N-methyl-d-aspartate, kainate, or glycine. Aluminum also did not reduce spontaneous excitatory synaptic activity, suggesting little, if any, effect on glutamate release. Although a causal role for aluminum in Alzheimer's disease and other neuropathological conditions remains controversial, it is clear that elevated aluminum concentrations in the brain are associated with a variety of cognitive impairments. The present results indicate that aluminum can alter the function of GABAA receptors and may suggest that aluminum can contribute to cognitive impairment through disruption of inhibitory circuits.

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8

Aldaya, Ivan, Elias Giacoumidis, Geraldo de Oliveira, Jinlong Wei, Julián Leonel Pita, Jorge Diego Marconi, Eric Alberto Mello Fagotto, Liam Barry, and Marcelo Luis Francisco Abbade. "Histogram Based Clustering for Nonlinear Compensation in Long Reach Coherent Passive Optical Networks." Applied Sciences 10, no. 1 (December 23, 2019): 152. http://dx.doi.org/10.3390/app10010152.

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In order to meet the increasing capacity requirements, network operators are extending their optical infrastructure closer to the end-user while making more efficient use of the resources. In this context, long reach passive optical networks (LR-PONs) are attracting increasing attention.Coherent LR-PONs based on high speed digital signal processors represent a high potential alternative because, alongside with the inherent mixing gain and the possibility of amplitude and phase diversity formats, they pave the way to compensate linear impairments in a more efficient way than in traditional direct detection systems. The performance of coherent LR-PONs is then limited by the combined effect of noise and nonlinear distortion. The noise is particularly critical in single channel systems where, in addition to the the elevated fibre loss, the splitting losses should be considered. In such systems, Kerr induced self-phase modulation emerges as the main limitation to the maximum capacity. In this work, we propose a novel clustering algorithm, denominated histogram based clustering (HBC), that employs the spatial density of the points of a 2D histogram to identify the borders of high density areas to classify nonlinearly distorted noisy constellations. Simulation results reveal that for a 100 km long LR-PON with a 1:64 splitting ratio, at optimum power levels, HBC presents a Q-factor 0.57 dB higher than maximum likelihood and 0.21 dB higher than k-means. In terms of nonlinear tolerance, at a BER of 2×10 − 3 , our method achieves a gain of ∼2.5 dB and ∼1.25 dB over maximum likelihood and k-means, respectively. Numerical results also show that the proposed method can operate over blocks as small as 2500 symbols.

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9

Cohen, D. A., M. Hossein-Zadeh, and A. F. J. Levi. "High-Q microphotonic electro-optic modulator." Solid-State Electronics 45, no. 9 (September 2001): 1577–89. http://dx.doi.org/10.1016/s0038-1101(01)00165-4.

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10

Alavi, M. S., R. B. Staszewski, L. C. N. de Vreede, A. Visweswaran, and J. R. Long. "All-Digital RF $I/Q$ Modulator." IEEE Transactions on Microwave Theory and Techniques 60, no. 11 (November 2012): 3513–26. http://dx.doi.org/10.1109/tmtt.2012.2211612.

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11

Angrisani, L., A. Napolitano, and M. Vadursi. "Measuring $I/Q$ Impairments in WiMAX Transmitters." IEEE Transactions on Instrumentation and Measurement 58, no. 5 (May 2009): 1299–306. http://dx.doi.org/10.1109/tim.2008.2009141.

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12

Blas, J. M., and J. I. Alonso. "Low cost wideband I-Q vector modulator." Electronics Letters 33, no. 1 (1997): 18. http://dx.doi.org/10.1049/el:19970031.

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13

Wang, Dong-Fei, Li-Ting Shan, and Lei Wang. "Photonic Filter-Free Scheme for D-Band mm-Wave Signal Generation with Frequency 12-Tupling Only via One Integrated In-Phase and Quadrature Modulator." Journal of Nanoelectronics and Optoelectronics 17, no. 1 (January 1, 2022): 40–47. http://dx.doi.org/10.1166/jno.2022.3167.

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In this work, we have proposed a new scheme of generating continuously tunable and filter-less D-band millimeter-wave (mm-wave) signal with frequency 12-tupling only via one integrated in-phase and quadrature (I/Q) modulator. The two sub-MZMs in the I/Q modulator, biased at peak point, are applied to eliminate odd order optical tones. By controlling the phase and amplitude of RF driving signals, I/Q modulator bias point, and the optical phase shifter embed in the lower arm of I/Q modulator, a frequency 12-tupling signal can be obtained through the beat frequency in the photodetector. Employing 10 GHz RF drive signal, 120 GHz millimeter wave signal can be realized by detailed mathematical formula derivation and simulation, and optical sideband suppression ratio (OSSR) can reach 37.65 dB and radio frequency sideband suppression ratio (RFSSR) can reach 32.08 dB.

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14

Escalante-Zarate, Luis, Yuri O. Barmenkov, José L. Cruz, and Miguel V. Andres. "Q-Switch Modulator as a Pulse Shaper in Q-Switched Fiber Lasers." IEEE Photonics Technology Letters 24, no. 4 (February 2012): 312–14. http://dx.doi.org/10.1109/lpt.2011.2178822.

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15

Schmalz, Klaus, Eckard Grass, Frank Herzel, and Maxim Piz. "An Integrated 5 GHz Wideband Quadrature Modem for OFDM Gbit/s Transmission in SiGe:C BiCMOS." International Journal of Microwave Science and Technology 2007 (October 1, 2007): 1–8. http://dx.doi.org/10.1155/2007/47927.

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This paper presents a 5 GHz wideband I/Q modulator/demodulator for 650 MHz OFDM signal bandwidth, which is integrated with a 5 GHz phase locked loop for I/Q generation. The quadrature signals are derived from a 10 GHz CMOS VCO followed by a bipolar frequency divider. The phase noise at 1 MHz offset is −112 dBc/Hz for the modulator as well as for the demodulator. The chips were produced in a 0.25 μm SiGe BiCMOS technology. The signal-to-noise ratio (SNR) of transmitted/received OFDM signal and the corresponding I/Q mismatch versus baseband frequency are given. The modulator achieves an SNR of 22–23 dB, and the demodulator realizes an SNR up to 22 dB. The modulator reaches a data rate of 2.16 Gbit/s using 64 QAM OFDM, and the demodulator realizes 1.92 Gbits/s.

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16

Linz, A., and A. Hendrickson. "Efficient implementation of an I-Q GMSK modulator." IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing 43, no. 1 (1996): 14–23. http://dx.doi.org/10.1109/82.481470.

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17

Epel, Boris, Subramanian V. Sundramoorthy, and Howard J. Halpern. "250 MHz passive Q-modulator for reflection resonators." Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering 47B, no. 2 (April 2017): e21356. http://dx.doi.org/10.1002/cmr.b.21356.

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18

Yang, Zhixian, Kun Qu, and Xiang Liu. "Frequency-Octupling Millimeter-Wave Optical Vector Signal Generation via an I/Q Modulator-Based Sagnac Loop." Symmetry 11, no. 1 (January 14, 2019): 84. http://dx.doi.org/10.3390/sym11010084.

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A new method for generating frequency-octupling millimeter-wave (mm-wave) vector signals in optical fields via a Sagnac loop is proposed. In this scheme, two orthogonally polarized fourth order sidebands can be obtained through an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator. The two optical sidebands are sent into an I/Q modulator-based Sagnac loop. The I/Q modulator is modulated by a 16QAM baseband signal. In the Sagnac loop, one of the sidebands is modulated by the baseband vector signal along one direction, and the other sideband is unmodulated along the opposite direction because the I/Q modulator has the traveling-wave nature. Thanks to this modulation property and the symmetrical structure of the Sagnac loop, a frequency-octupling mm-wave vector signal that is free from interband beating and fiber chromatic dispersion interference can be generated by the photodetector (PD). After simulating a 20 km single-mode fiber (SMF) transmission, the generated frequency-octupling vector signal was good in function.

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19

Young, A. W. "Face processing impairments and delusional misidentification." Neurocase 4, no. 3 (June 1, 1998): 255q—264. http://dx.doi.org/10.1093/neucas/4.3.255-q.

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20

Aziz, Mohsin, Fadhel Ghannouchi, and Mohamed Helaoui. "Blind Compensation of I/Q Impairments in Wireless Transceivers." Sensors 17, no. 12 (December 19, 2017): 2948. http://dx.doi.org/10.3390/s17122948.

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21

Angrisani, L., R. S. L. Moriello, and M. Vadursi. "Measuring Time-Varying $I/Q$ Impairments in Digital Transmitters." IEEE Transactions on Instrumentation and Measurement 58, no. 10 (October 2009): 3510–18. http://dx.doi.org/10.1109/tim.2009.2018005.

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22

Capmany, J., J. Mora, B. Ortega, and D. Pastor. "High-Q microwave photonic filter with a tuned modulator." Optics Letters 30, no. 17 (September 1, 2005): 2299. http://dx.doi.org/10.1364/ol.30.002299.

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23

El-Nahal, Fady. "Coherent 16 Quadrature Amplitude Modulation (16QAM) Optical Communication Systems." Photonics Letters of Poland 10, no. 2 (June 30, 2018): 57. http://dx.doi.org/10.4302/plp.v10i2.809.

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Coherent optical fiber communications for data rates of 100Gbit/s and beyond have recently been studied extensively primarily because high sensitivity of coherent receivers could extend the transmission distance. Spectrally efficient modulation techniques such as M-ary quadrature amplitude modulation (M-QAM) can be employed for coherent optical links. The integration of multi-level modulation formats based on coherent technologies with wavelength-division multiplexed (WDM) systems is key to meet the aggregate bandwidth demand. This paper reviews coherent 16 quadrature amplitude modulation (16QAM) systems to scale the network capacity and maximum reach of current optical communication systems to accommodate traffic growth. Full Text: PDF ReferencesK. Kikuchi, "Fundamentals of Coherent Optical Fiber Communications", J. Lightwave Technol., vol. 34, no. 1, pp. 157-179, 2016. CrossRef S. Tsukamoto, D.-S. Ly-Gagnon, K. Katoh, and K. Kikuchi, "Coherent Demodulation of 40-Gbit/s Polarization-Multiplexed QPSK Signals with16-GHz Spacing after 200-km Transmission", Proc. OFc, Paper PDP29, (2005). DirectLink K. Kikuchi, "Coherent Optical Communication Technology", Proc. OFC, Paper Th4F.4, (2015). CrossRef J. M. Kahn and K.-P. Ho, "Spectral efficiency limits and modulation/detection techniques for DWDM systems", IEEE J. Sel. Topics Quantum Electron., vol. 10, no. 2, pp. 259–272, (2004). CrossRef S. Tsukamoto, K. Katoh, and K. Kikuchi, "Coherent demodulation of optical multilevel phase-shift-keying signals using homodyne detection and digital signal processing", IEEE Photon. Technol. Lett., vol. 18, no. 10, pp. 1131–1133, (2006). CrossRef Y. Mori, C. Zhang, K. Igarashi, K. Katoh, and K. Kikuchi, "Unrepeated 200-km transmission of 40-Gbit/s 16-QAM signals using digital coherent receiver", Opt. Exp., vol. 17, no. 32, pp. 1435–1441, (2009). CrossRef H. Nakashima, Et al., "Digital Nonlinear Compensation Technologies in Coherent Optical Communication Systems", Proc. OFC, Paper W1G.5, (2017). CrossRef S. J. Savory, "Digital filters for coherent optical receivers", Opt. Exp., vol. 16, no. 2, pp. 804–817, (2008). CrossRef D. S. Millar, T. Koike-Akino, S. Ö. Arık, K. Kojima, K. Parsons, T. Yoshida, and T. Sugihara, "High-dimensional modulation for coherent optical communications systems", Opt. Express, vol. 22, no. 7, pp 8798-8812, (2014). CrossRef R. Griffin and A. Carter, "Optical differential quadrature phase-shift key (oDQPSK) for high capacity optical transmission", Proc. OFC, Paper WX6, (2002). DirectLink K. Kikuchi, "Digital coherent optical communication systems: fundamentals and future prospects", IEICE Electron. Exp., vol. 8, no. 20, pp. 1642–1662, (2011). CrossRef F. Derr, "Optical QPSK transmission system with novel digital receiver concept", Electron Lett., vol. 27, no. 23, pp. 2177–2179, (1991). CrossRef R. No’e, "Phase noise tolerant synchronous QPSK receiver concept with digital I&Q baseband processing", Proc. OECC, Paper 16C2-5, (2004). DirectLink D.-S. Ly-Gagnon, S. Tsukamoto, K. Katoh, and K. Kikuchi, "Coherent detection of optical quadrature phase-shift keying signals with carrier phase estimation", J. Lightw. Technol., vol. 24, no. 1, pp. 12–21, (2006). CrossRef M. Taylor, "Coherent detection method using DSP for demodulation of signal and subsequent equalization of propagation impairments", IEEE Photon. Technol. Lett., vol. 16, no. 2, pp. 674–676, (2004). CrossRef S. Tsukamoto, K. Katoh, and K. Kikuchi, "Unrepeated transmission of 20-Gb/s optical quadrature phase-shift-keying signal over 200-km standard single-mode fiber based on digital processing of homodyne-detected signal for Group-velocity dispersion compensation", IEEE Photon. Technol. Lett., vol. 18, no. 9, pp. 1016–1018, (2006). CrossRef S. Tsukamoto, Y. Ishikawa, and K. Kikuchi, "Optical Homodyne Receiver Comprising Phase and Polarization Diversities with Digital Signal Processing", Proc. ECOC, Paper Mo4.2.1, (2006). CrossRef K. Kikuchi and S. Tsukamoto, "Evaluation of Sensitivity of the Digital Coherent Receiver", J. Lightw. Technol., vol. 20, no. 13, pp. 1817–1822, (2008). CrossRef S. Ishimura and K. Kikuchi, "Multi-dimensional Permutation Modulation Aiming at Both High Spectral Efficiency and High Power Efficiency", Proc. OFC/NFOEC, Paper M3A.2, (2014). CrossRef F. I. El-Nahal and A. H. M. Husein, "Radio over fiber access network architecture employing RSOA with downstream OQPSK and upstream re-modulated OOK data", (Optik) Int. J. Light Electron Opt., vol. 123, no. 14, pp: 1301-1303, (2012). CrossRef T. Koike-Akino, D. S. Millar, K. Kojima, and K. Parsons, "Eight-Dimensional Modulation for Coherent Optical Communications", Proc. ECOC, Paper Tu.3.C.3, (2013). DirectLink B. Sklar, Digital communications: Fundamentals and Applications, Prentice-Hall, (2001).

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24

Gupta, Arpit K., Joohwa Kim, Peter Asbeck, and James F. Buckwalter. "A 9 mW, Q-Band Direct-Conversion I/Q Modulator in SiGe BiCMOS Process." IEEE Microwave and Wireless Components Letters 22, no. 6 (June 2012): 327–29. http://dx.doi.org/10.1109/lmwc.2012.2197379.

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25

Kiayani, Adnan, Lauri Anttila, Yaning Zou, and Mikko Valkama. "Advanced Receiver Design for Mitigating Multiple RF Impairments in OFDM Systems: Algorithms and RF Measurements." Journal of Electrical and Computer Engineering 2012 (2012): 1–16. http://dx.doi.org/10.1155/2012/730537.

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Direct-conversion architecture-based orthogonal frequency division multiplexing (OFDM) systems are troubled by impairments such as in-phase and quadrature-phase (I/Q) imbalance and carrier frequency offset (CFO). These impairments are unavoidable in any practical implementation and severely degrade the obtainable link performance. In this contribution, we study the joint impact of frequency-selective I/Q imbalance at both transmitter and receiver together with channel distortions and CFO error. Two estimation and compensation structures based on different pilot patterns are proposed for coping with such impairments. The first structure is based on preamble pilot pattern while the second one assumes a sparse pilot pattern. The proposed estimation/compensation structures are able to separate the individual impairments, which are then compensated in the reverse order of their appearance at the receiver. We present time-domain estimation and compensation algorithms for receiver I/Q imbalance and CFO and propose low-complexity algorithms for the compensation of channel distortions and transmitter IQ imbalance. The performance of the compensation algorithms is investigated with computer simulations as well as with practical radio frequency (RF) measurements. The performance results indicate that the proposed techniques provide close to the ideal performance both in simulations and measurements.

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26

Gao, Yongsheng, Aijun Wen, Wei Jiang, Yangyu Fan, Deyun Zhou, and You He. "Wideband Photonic Microwave SSB Up-Converter and I/Q Modulator." Journal of Lightwave Technology 35, no. 18 (September 15, 2017): 4023–32. http://dx.doi.org/10.1109/jlt.2017.2726532.

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27

Luo, Jian, Wilhelm Keusgen, and Andreas Kortke. "Efficient Joint Estimation and Compensation of CFO, Tx/Rx Frequency-Selective I/Q Imbalance, and the MIMO Radio Channel in OFDM Systems." Journal of Electrical and Computer Engineering 2013 (2013): 1–20. http://dx.doi.org/10.1155/2013/679032.

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MIMO OFDM is a very promising technique for future wireless communication systems. By applying direct conversion architecture, low-cost, low-power, small size, and flexible implementation of MIMO OFDM systems can be realized. However, the performance of direct conversion architecture-based MIMO OFDM systems can be seriously affected by RF impairments incling carrier frequency offset (CFO) and I/Q-imbalance. While OFDM is sensitive to CFO, direct conversion architecture is sensitive to I/Q imbalance. Such RF impairments aggravate as the carrier frequency becomes higher for example, beyond 60 GHz. To achieve the desired high performance of MIMO OFDM, such RF impairments have to be compensated for. In this paper, the joint compensation of CFO, transmitter and receiver frequency-selective I/Q imbalance, and the MIMO radio channel is investigated. Two preamble-based schemes are proposed for impairment parameter estimation. The proposed preambles are constructed both in time and frequency domains and require much less overhead than the state-of-the-art designs. Furthermore, much lower computational complexity is allowed, enabling efficient implementation. The advantages and effectiveness of both proposed schemes are compared and verified by numerical simulations and complexity analysis.

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28

Zhang, Qin, and Zhi Bin Zeng. "Simulation Analysis on DPD Performance with DC Offset." Applied Mechanics and Materials 380-384 (August 2013): 4108–11. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.4108.

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DC offset of the input analog signal I and Q of quadrature modulator which is as DAC and RF channel interface will affect bit error rate (BER) of the system, the quality of the emission signals and the overall effect of DPD[. This paper focuses on the influences of non-ideal characteristics quadradure modulator on DPD technology.

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29

Angrisani, L., and R. Colella. "Detection and evaluation of I/Q impairments in RF digital transmitters." IEE Proceedings - Science, Measurement and Technology 151, no. 1 (January 1, 2004): 39–45. http://dx.doi.org/10.1049/ip-smt:20040005.

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30

Pun, K. P., C. S. Choy, C. F. Chan, and J. E. da Franca. "An I/Q Mismatch-Free Switched-Capacitor Complex Sigma–Delta Modulator." IEEE Transactions on Circuits and Systems II: Express Briefs 51, no. 5 (May 2004): 254–56. http://dx.doi.org/10.1109/tcsii.2004.827552.

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31

Paramonov, V. M., and A. S. Kurkov. "Q-switched Er-doped fiber source based on electrooptical modulator application." Laser Physics 25, no. 6 (May 1, 2015): 065103. http://dx.doi.org/10.1088/1054-660x/25/6/065103.

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32

Lv, Qiang, Kun Xu, Yitang Dai, Yan Li, Jian Wu, and Jintong Lin. "I/Q intensity-demodulation analog photonic link based on polarization modulator." Optics Letters 36, no. 23 (November 28, 2011): 4602. http://dx.doi.org/10.1364/ol.36.004602.

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33

Kim, Jusung, Han-Shin Jo, Kyoung-Jae Lee, Dong-Ho Lee, Dae-Hyun Choi, and Sangkil Kim. "A Low-Complexity I/Q Imbalance Calibration Method for Quadrature Modulator." IEEE Transactions on Very Large Scale Integration (VLSI) Systems 27, no. 4 (April 2019): 974–77. http://dx.doi.org/10.1109/tvlsi.2018.2883758.

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SAN, H. "Complex Bandpass AD Modulator Architecture without I, Q-Path Crossing Layout." IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E89-A, no. 4 (April 1, 2006): 908–15. http://dx.doi.org/10.1093/ietfec/e89-a.4.908.

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Hosseini-Sharifabad, Ali, Mohammad Reza Mofid, Majid Moradmand, and Mohammad Keimasi. "The Effect of Omega-lycotoxin on the Cognitive Impairment Induced by Kainic Acid in Rats." Iranian Journal of Toxicology 15, no. 1 (January 1, 2021): 49–56. http://dx.doi.org/10.32598/ijt.15.1.740.1.

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Background: Excitotoxicity is a common pathological process in neurodegenerative diseases associated with overactivity of N-methyl-D-aspartate (NMDA) and P/Q type voltage-gated calcium (Cav2.1) channels. Omega-lycotoxin-Gsp2671g is a therapeutic tool to modulate overactive Cav2.1 (P/Q type) channels. Omega-lycotoxin binds to Cav2.1 channels with high affinity and selectivity. This study aimed to investigate the effects of Omega-lycotoxin on the cognitive impairment induced by kainic acid in rats. Methods: The effect of pre-treatment and post-treatment trials of intra-hippocampal Cornu Ammonis-3 administration of omega-lycotoxin (0.5, 1 or 2µg) was studied on the cognitive impairment induced by kainic acid in rats. The rats’ learning and memory were assessed by the passive avoidance and a single-day testing version of the Morris water maze method. Results: Omega-lycotoxin caused a significant increase in the latency of the passive avoidance test and the duration of their presence in the target area of the Morris water maze test compared to the groups treated with kainic acid (P<0.0001). There were statistically significant differences for the effects of various doses of omega-lycotoxin. The post-treatment groups showed a greater improvement than those in the pretreatment groups. Conclusion: The findings demonstrated that a single dose of omega-lycotoxin can prevent or revert the memory impairment caused by kainic acid in rats.

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M. A. Eid, Mahmoud, Ashraf S. Seliem, Ahmed Nabih Zaki Rashed, Abd El-Naser A. Mohammed, Mohamed Yassin Ali, and Shaimaa S. Abaza. "The key management of direct/external modulation semiconductor laser response systems for relative intensity noise control." Indonesian Journal of Electrical Engineering and Computer Science 21, no. 2 (February 1, 2021): 968. http://dx.doi.org/10.11591/ijeecs.v21.i2.pp968-977.

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<p><span>This study outlines the management of either direct or external modulation semiconductor laser systems for the key solution of bit rate up to 25 Gb/s under relative intensity noise (RIN) control. The bias and modulation peak currents based laser rate equations are optimized to achieve max Q factor and min bit error rate (BER) using first proposed model and optical/electrical signal power, optical/electrical signal to noise ratio are also enhanced using second proposed model. The percentage enhancement ratio in max. Q-factor and min. BER using first proposed model ranges from 53.25 % to 71.63 % in compared to the previous model. In the same way, by using second proposed model, the electrical signal power at optical receiver is enhanced within the range of 48.66 % to 68.88 % in compared to the previous model. Optical signal/noise ratio (OSNR) after optical fiber cable (OFC), signal/noise ratio (SNR) after electrical filter are measured with using different electrical pulse generators and electrical modulators at the optimization stage. The first proposed model reported better max. Q and min. BER values than the previous model. In addition to the second proposed model (direct modulation) has outlined better optical/electrical signal power than the previous model, while max. Q, min. BER values are kept constant. It is found that non return to zero pulse generator has presented better signal power than other pulse generators by using second proposed model. As well as the mixed of raised cosine pulse generator with external modulator reported max. Q, min. BER with other pulse generators by using first proposed model. OSNR at OFC is optimized by using continuous phase frequency shift keying (CPFSK) electrical modulator, While SNR at optical receiver is optimized by using phase shift keying (PSK) electrical modulator.</span></p>

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Yi, Minwoo, Sungjun Yoo, Youngseok Bae, Sunghoon Jang, Joonhyung Ryoo, and Jinwoo Shin. "Design and Manufacture of Traveling-wave Electro-optic Modulator for X-band LFM Signal Generation." Journal of the Korea Institute of Military Science and Technology 24, no. 6 (December 5, 2021): 610–18. http://dx.doi.org/10.9766/kimst.2021.24.6.610.

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In this paper, a photonic-based microwave system technology is described, and a traveling-wave electro-optic modulator is designed and manufactured as a key component. The fabricated modulator is composed of a metal diffusion waveguide for optical transmission and a planar waveguide electrode on lithium niobate substrate for microwave transmission. The electro-optic response bandwidth of I and Q channels in a fabricated dual parallel Mach-Zehnder modulator were measured for 27.67 and 28.11 GHz, respectively. Photonic four times up-converted X-band frequency and linear frequency modulated signal were confirmed using the fabricated electro-optic modulator by S-band input signal. The confirmed broadband signal can be applied to a microwave system for surveillance and high-resolution ISAR imaging.

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Chen, Tenghui, Weichao Yao, Hiyori Uehara, Chunyang Ma, Muhammad Sohail, Chunxiang Zhang, Yanqi Ge, Dianyuan Fan, and Jun Liu. "High-peak-power and wavelength tunable acousto-optic Q-switched Er:ZBLAN fiber laser." Japanese Journal of Applied Physics 61, no. 4 (March 17, 2022): 040902. http://dx.doi.org/10.35848/1347-4065/ac58d5.

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Abstract We demonstrate Q-switching operation of a single-moded mid-infraredEr3+-doped ZBLAN (Er:ZBLAN) fiber laser based on an acousto-optic modulator. The fiber laser can produce steady Q-switched pulses as short as 24.8 ns at an average output power of 45.7 mW with a single transverse mode, corresponding to a peak power of 18.4 kW. In addition, a wavelength tuning range from 2715.4 to 2790.4 nm is also achieved in the Q-switching regime at the repetition rate of 1 kHz. The experimental results demonstrate the huge potential of producing mid-infrared energetic and wavelength tunable short-pulses in an actively Q-switched Er:ZBLAN fiber laser.

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Zhao, Mingming, Wen Zhou, Li Zhao, Jiangnan Xiao, Xinying Li, Feng Zhao, and Jianjun Yu. "A New Scheme to Generate Multi-Frequency Mm-Wave Signals Based on Cascaded Phase Modulator and I/Q Modulator." IEEE Photonics Journal 11, no. 5 (October 2019): 1–8. http://dx.doi.org/10.1109/jphot.2019.2939275.

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Hirooka, Toshihiko, and Masataka Nakazawa. "Q-factor analysis of nonlinear impairments in ultrahigh-speed Nyquist pulse transmission." Optics Express 23, no. 26 (December 18, 2015): 33484. http://dx.doi.org/10.1364/oe.23.033484.

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Kedia, Deepak, and Monika Nehra. "Extended Reach 10 Gb/s Transmission with an Optical I/Q Modulator Using VCSELs over OFDM-Based Multimode Fiber Link." International Journal of Optics 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/2395495.

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This paper investigates the possibilities of extending the reach of a 10 Gb/s orthogonal frequency division multiplexing- (OFDM-) based multimode fiber (MMF) link with an optical I/Q modulation technique through vertical cavity surface emitting lasers (VCSELs). The proposed I/Q modulation technique comprises two VCSELs in a 90° hybrid combination to produce I/Q modulated OFDM signal. The results show the excellent performance (in terms of BER and Q factor) of the direct-detection optical- (DDO-) OFDM system with the proposed I/Q modulation in comparison to the direct modulation case. The proposed system is able to achieve worst-case BER of about 1.8616 × 10−3 and Q factor of about 10.9949 dB over a 5 km MMF link. The I/Q modulation technique in the DDO-OFDM system has further been investigated for extending the transmission reach of the MMF link using multispan configuration.

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Zhao, J., K. Li, F. Kong, K. Cheng, and B. Zhao. "Diode-pumped actively Nd:Lu0.33Y0.37Gd0.3VO4 Q-switched laser with electro-optic (EO) modulator." Laser Physics 22, no. 5 (April 3, 2012): 911–13. http://dx.doi.org/10.1134/s1054660x12050374.

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Zhuo, Z., J. M. Jiang, T. Li, S. G. Li, C. X. Shan, H. B. Qin, J. Li, B. Zhao, and J. Z. Chen. "Study of LD pumped Q-switched Nd:Y0.5Lu0.5VO4 laser with acousto-optic modulator." Laser Physics 21, no. 9 (July 4, 2011): 1558–61. http://dx.doi.org/10.1134/s1054660x11150370.

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Zhao, S., J. Zhao, G. Li, K. Yang, Y. Sun, D. Li, J. An, J. Wang, and M. Li. "Doubly Q-switched laser with electric-optic modulator and GaAs saturable absorber." Laser Physics Letters 3, no. 10 (October 1, 2006): 471–73. http://dx.doi.org/10.1002/lapl.200610038.

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Yubing, T., T. Huiming, P. Jiying, and L. HongYi. "LD-pumped actively Q-switched Yb:YAG laser with an acoustic-optical modulator." Laser Physics 18, no. 1 (January 2008): 12–14. http://dx.doi.org/10.1134/s1054660x08010027.

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Singal, Anuj, and Deepak Kedia. "Performance Analysis of Antenna Selection Techniques in MIMO-OFDM System with Hardware Impairments: Energy Efficiency perspective." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 4 (August 1, 2018): 2272. http://dx.doi.org/10.11591/ijece.v8i4.pp2272-2279.

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<p>In this paper we propose a new MIMO-OFDM model in which we consider various antenna selection techniques like Bulk selection and Per-subcarrier selection etc. with hardware impairments such as non-linearties of amplifiers, quantization noise, phase noise and I-Q imbalance etc. As we know that the transceiver hardware impairments limit the channel capacity and the energy efficiency of MIMO-OFDM system, so we can not neglect the fundamental impacts of these hardware impairments {Kappa (0.05 0.1)} on the energy efficiency in the high SNR domain. Therefore we analyze the Energy Efficiency of Bulk and Per-subcarrier antenna selection techniques with or without hardware impairments. It has been observed that the energy efficiency decreases as the value of these hardware impairments increases. As we compared the Bulk antenna selection with the Per-subcarrier antenna selection scheme, the Per-subcarrier antenna selection requires more number of RF (radio frequency) chains and transmits power in comparison to the Bulk selection. Due to this, the Bulk antenna selection technique is more energy efficient than Per-subcarrier antenna selection.</p>

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Sharma, Seema, and Suresh Vir Singh Rana. "Melatonin Improves Liver Function in Benzene-Treated Rats." Archives of Industrial Hygiene and Toxicology 64, no. 2 (June 1, 2013): 219–27. http://dx.doi.org/10.2478/10004-1254-64-2013-2248.

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In this study, we investigated the beneficial effects of melatonin against benzene-induced liver function impairments in Wistar rats. After 30 days of treatment, it significantly lowered hepatosomatic indices, bilirubin, and hydroxyproline in male and female benzene-treated rats. Even though it did not influence aspartate aminotransferase, melatonin had beneficial effects on alanine aminotransferase and alkaline phosphatase. Our results suggest that melatonin is an effective modulator of liver function in benzenetreated rats thanks to its antioxidative properties.

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Nehra, Monika, and Deepak Kedia. "Design of Optical I/Q Modulator Using Dual-drive Mach-Zehnder Modulators in Coherent Optical-OFDM System." Journal of Optical Communications 39, no. 2 (April 25, 2018): 155–59. http://dx.doi.org/10.1515/joc-2016-0089.

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AbstractA CO-OFDM system combines the advantages of both coherent detection and OFDM modulation for future high speed fiber transmission. In this paper, we propose an I/Q modulation technique using dual-drive MZMs for high rate 10 Gb/s CO-OFDM system. The proposed modulator provides 10.63 dBm improved optical spectra compared to a single dual-drive MZM. The simulation results in terms of BER and Q factor are quite satisfactory upto a transmission reach of 3,000 km and that to without making use of any dispersion compensation. A BER of about 8.03×10−10and 15.06 dB Q factor have been achieved at −10.43 dBm received optical power.

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Brigham, Christopher R., Kathryn Mueller, Steven Demeter, and Randolph Soo Hoo. "Q&A: Multiple Lower Extremity Impairments and AMA Guides, Third Edition, Revised." Guides Newsletter 22, no. 2 (March 1, 2017): 15–16. http://dx.doi.org/10.1001/amaguidesnewsletters.2017.marapr05.

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Gao, Zhi Qiang, Jin Bao Lan, Xiao Wei Liu, and Liang Yin. "The Delta-Sigma Modulator of Fractional-N Frequency Synthesizer for Wireless Sensors Network Applications." Key Engineering Materials 609-610 (April 2014): 1014–19. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.1014.

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This paper presents a design of fractional-N frequency synthesizer with low dithering, which is fabricated in a 130nm CMOS process. A 3rd-order delta-sigma modulator is based on digital multi-stage noise shaping (MASH) structure with its second and third stage dithered by 7-bit linear feedback shift register (LFSR) was designed for the frequency synthesizer, and a long word is used for the first modulator in the MASH structure. The simulation result of the whole frequency synthesizer shows that it can output two-way I/Q signal between 2.28GHz and 2.53GHz, and its spurs are lower than-75dBc.

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