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Journal articles on the topic 'Impedance mismatch'

Author: Grafiati

Published: 4 June 2021

Last updated: 12 June 2025

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1

Pathan, Erum, Afarulrazi Abu Bakar, Mubashir Hayat Khan, Muhammad Asad, and Haider Arshad. "Multiloop low bandwidth communication-based power sharing control for microgrids." Indonesian Journal of Electrical Engineering and Computer Science 21, no. 2 (2020): 682. http://dx.doi.org/10.11591/ijeecs.v21.i2.pp682-690.

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<span>In parallel-connected inverter-based microgrids, the reactive power sharing accuracy can not have satisfactory results effortlessly. Mismatch in feeder impedances of the parallel-connected inverter-based microgrids is a significant cause of inaccurate reactive power-sharing. In voltage source inverters (VSI) based microgrids, especially for the islanded mode of operation, the conventional centralized or decentralized control techniques are not much helpful to control the voltage deviations due to impedance mismatch. Mismatch of the feeder impedance is compensated by the addition of fixed virtual impedance. Whereas, the change in the virtual impedance is compensated by adaptive virtual impedance-based control techniques which are helpful to mitigate power-sharing errors, but in most of the control schemes virtual impedance-based control mechanism needs pre-knowledge of feeder impedance which increases the computational burden. This paper presents a decentralized virtual impedance-based power sharing control. In the proposed control solution to mitigate reactive power sharing errors in distributed generation (DG) units, mismatch of the parallel-connected feeder impedance is equalized by regulating the addition of equivalent impedance to each DG inverter. Proposed control technique offers an independent implementation without any pre-knowledge of the feeder impedance. Hence, the implementation of the control scheme is a straightforward and computational burden is also reduced. Simulation results show the effectiveness of the control scheme. </span>

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2

Cherkasova, P. G., and B. A. Novikov. "Seamless design: Impedance mismatch revisited." Programming and Computer Software 32, no. 5 (2006): 268–75. http://dx.doi.org/10.1134/s0361768806050033.

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3

Ngavouka, Maryse D. Nkoua, Pietro Capaldo, Elena Ambrosetti, Giacinto Scoles, Loredana Casalis, and Pietro Parisse. "Mismatch detection in DNA monolayers by atomic force microscopy and electrochemical impedance spectroscopy." Beilstein Journal of Nanotechnology 7 (February 9, 2016): 220–27. http://dx.doi.org/10.3762/bjnano.7.20.

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Background: DNA hybridization is at the basis of most current technologies for genotyping and sequencing, due to the unique properties of DNA base-pairing that guarantee a high grade of selectivity. Nonetheless the presence of single base mismatches or not perfectly matched sequences can affect the response of the devices and the major challenge is, nowadays, to distinguish a mismatch of a single base and, at the same time, unequivocally differentiate devices read-out of fully and partially matching sequences. Results: We present here two platforms based on different sensing strategies, to detect mismatched and/or perfectly matched complementary DNA strands hybridization into ssDNA oligonucleotide monolayers. The first platform exploits atomic force microscopy-based nanolithography to create ssDNA nano-arrays on gold surfaces. AFM topography measurements then monitor the variation of height of the nanostructures upon biorecognition and then follow annealing at different temperatures. This strategy allowed us to clearly detect the presence of mismatches. The second strategy exploits the change in capacitance at the interface between an ssDNA-functionalized gold electrode and the solution due to the hybridization process in a miniaturized electrochemical cell. Through electrochemical impedance spectroscopy measurements on extended ssDNA self-assembled monolayers we followed in real-time the variation of capacitance, being able to distinguish, through the difference in hybridization kinetics, not only the presence of single, double or triple mismatches in the complementary sequence, but also the position of the mismatched base pair with respect to the electrode surface. Conclusion: We demonstrate here two platforms based on different sensing strategies as sensitive and selective tools to discriminate mismatches. Our assays are ready for parallelization and can be used in the detection and quantification of single nucleotide mismatches in microRNAs or in genomic DNA.

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4

Wang, Da Long, Zheng Bin Wu, and Jian Wang. "Study of Effects of Differential via on Signal Integrity." Advanced Materials Research 805-806 (September 2013): 1011–16. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.1011.

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If characteristic impedance along a transmission line mismatch on a printed circuit board, high-speed signal has serious signal integrity problems. When signal path of a differential pair jumps layers, mismatched impedance between differential via and differential line will affect the signal integrity. The models of a coupled transmission line and via are presented in this paper. Impedance matching of the coupled transmission line and differential via for differential signals is studied. The effects of differential via dimensions on differential signals is simulated and analyzed.

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5

Chen, Liang, Heng Nian, and Yunyang Xu. "Impedance Aggregation Method of Multiple Wind Turbines and Accuracy Analysis." Energies 12, no. 11 (2019): 2035. http://dx.doi.org/10.3390/en12112035.

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The sequence domain impedance modeling of wind turbines (WTs) has been widely used in the stability analysis between WTs and weak grids with high line impedance. An aggregated impedance model of the wind farm is required in the system-level analysis. However, directly aggregating WT small-signal impedance models will lead to an inaccurate aggregated impedance model due to the mismatch of reference frame definitions among different WT subsystems, which may lead to inaccuracy in the stability analysis. In this paper, we analyze the impacts of the reference frame mismatch between a local small-signal impedance model and a global one on the accuracy of aggregated impedance and the accuracy of impedance-based stability analysis. The results revealed that the impact is related to the power distribution of the studied network. It was found that that the influence of mismatch on stability analysis became subtle when subsystems were balanced loaded. Considering that balanced loading is a common configuration of the practical application, direct impedance aggregation by local small-signal models can be applied due to its acceptable accuracy.

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6

Hu, Bo, Moran Wang, and Yimei Du. "The influence of impedance mismatch of the medium with gradient change of impedance on acoustic characteristics." MATEC Web of Conferences 283 (2019): 09005. http://dx.doi.org/10.1051/matecconf/201928309005.

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Medium with gradient change of acoustic impedance is a new type acoustic structure. It is composed of several materials and has a continuous gradient composition and structure whose specific acoustic impedance varies smoothly across the layer. It has been used in various practical situations such as acoustic rectifiers, medical devices, weakening vibration and reducing noise. The purpose of this paper is to investigate the effect of boundary impedance mismatch on acoustic characteristics of gradient impedance media. The propagation mechanism of acoustic waves in medium with gradient change of specific acoustic impedance was calculated by transfer matrix method. By setting the different ratios of the acoustic impedance at interfaces of matching layer, the relationship between specific acoustic impedance mismatch and acoustic characteristics are derived and the corresponding conclusions are drawn. These conclusions provide an idea for the preparation of relevant medium.

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7

Wang and Cao. "A Review of Impedance Matching Techniques in Power Line Communications." Electronics 8, no. 9 (2019): 1022. http://dx.doi.org/10.3390/electronics8091022.

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Impedance mismatch that degrades signal power transfer and affects communication reliability is a major obstacle for power line communications (PLC). Impedance matching techniques can be designed to effectively compensate for the impedance mismatch between PLC modems and power line networks at a specific frequency or for a given frequency band. In this paper, we discuss the tradeoffs that need to be made when designing an effective impedance matching network. We also make a comprehensive review of previous state-of-the-art PLC impedance matching techniques and provide a useful classification of each technique. Finally, we discuss important issues (concerns) and provide suggestions for research directions deserving more attention. This review provides a useful guideline for researchers and manufacturers to quickly understand impedance matching principles and facilitate the design of an effective impedance matching coupler for PLC applications.

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8

Tang, Yue, Ronghui Chang, Limin Zhang, and Feng Yan. "An Interference Suppression Method for Non-Contact Bioelectric Acquisition." Electronics 9, no. 2 (2020): 293. http://dx.doi.org/10.3390/electronics9020293.

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For non-contact bioelectrical acquisition, a new interference suppression method, named ‘noise neutralization method’, is proposed in this paper. Compared with the traditional capacitive driven-right-leg method, the proposed method is characterized with that there is an optimal gain to achieve the minimum interference output whatever for the electrode interface impedance mismatch caused by body motion and is more effective for smaller reference electrode areas. The performance of traditional capacitive driven-right-leg method is analyzed and the difficulty to suppress interference in the case of the interface impedance mismatch is pointed out. Therefore, a noise neutralization method is proposed by applying the reference electrode and a 50 Hz band-pass filter to obtain the interference of the human body and adapting the gains to neutralize the interference inputs of two acquisition electrodes and achieve the minimum interference output. The performance of the proposed method is theoretically analyzed and verified by the experiment results, which shows that the proposed method has similar performance to that of the traditional capacitive driven-right-leg method with electrode interface impedance match, while has better interference suppression ability with electrode interface impedance mismatch caused by body motion. It is suggested that the proposed method can be preferred in the case of limited reference electrode area or interface impedance mismatch.

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9

Livshits, Pavel, Moshe Gurfinkel, and Yefim Fefer. "VLSI MOSFETs lifetime reduction caused by impedance mismatch." Microelectronic Engineering 88, no. 1 (2011): 28–31. http://dx.doi.org/10.1016/j.mee.2010.08.012.

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10

Fletcher, N. H., J. Smith, A. Z. Tarnopolsky, and J. Wolfe. "Acoustic impedance measurements—correction for probe geometry mismatch." Journal of the Acoustical Society of America 117, no. 5 (2005): 2889–95. http://dx.doi.org/10.1121/1.1879192.

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11

Jusserand, B., R. Ghasemi, E. Dynowska, M. Wiater, G. Karczewski, and T. Wojtowicz. "Large acoustic impedance mismatch in CdTe/MgTe nanodevices." Applied Physics Letters 94, no. 9 (2009): 093102. http://dx.doi.org/10.1063/1.3089847.

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12

Jeon, Jooyoung, and Myounggon Kang. "A Ruggedness Improved Mobile Radio Frequency Power Amplifier Module with Dynamic Impedance Correction by Software Defined Atomization." Electronics 8, no. 11 (2019): 1317. http://dx.doi.org/10.3390/electronics8111317.

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A ruggedness improved multi-band radio frequency (RF) power amplifier (PA) module applicable to mobile handsets, which are required to survive against a serious load impedance change under extreme power and bias conditions, is presented. In this method, the load impedance of PA is adaptively adjusted with a digitally controlled impedance corrector to keep the PA safe by performing a load mismatch detection. The impedance mismatch detector, impedance corrector, and other RF switches were all integrated into a single integrated circuit (IC) using silicon on insulator (SOI) complementary metal oxide semiconductor (CMOS). For the verification purpose, a 2-stage hetero junction bipolar transistor (HBT) PA module adopting this method was fabricated. At a frequency of 1915 MHz, a collector bias voltage of 4.2 V, and over a wider range of load impedance variation between a VSWR of 1 and a VSWR of 5.5, it did not fail. When this technique was not applied with a voltage standing wave ratio (VSWR) range of 1 to 4, it resulted in an acceptable RF performance degradation of 1% power added efficiency (PAE) in envelope tracking (ET) mode. Moreover, it survived at a bias voltage 1V larger than when the technique was not applied for the same mismatch condition.

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13

Zheng, Xiaomin, Yuejun Zhang, Jiaweng Zhang, and Wenqi Hu. "Design Impedance Mismatch Physical Unclonable Functions for IoT Security." Active and Passive Electronic Components 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/4070589.

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We propose a new design, Physical Unclonable Function (PUF) scheme, for the Internet of Things (IoT), which has been suffering from multiple-level security threats. As more and more objects interconnect on IoT networks, the identity of each thing is very important. To authenticate each object, we design an impedance mismatch PUF, which exploits random physical factors of the transmission line to generate a security unique private key. The characteristic impedance of the transmission line and signal transmission theory of the printed circuit board (PCB) are also analyzed in detail. To improve the reliability, current feedback amplifier (CFA) method is applied on the PUF. Finally, the proposed scheme is implemented and tested. The measure results show that impedance mismatch PUF provides better unpredictability and randomness.

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14

Bogónez-Franco, P., L. Nescolarde, R. Bragós, J. Rosell-Ferrer, and I. Yandiola. "Measurement errors in multifrequency bioelectrical impedance analyzers with and without impedance electrode mismatch." Physiological Measurement 30, no. 7 (2009): 573–87. http://dx.doi.org/10.1088/0967-3334/30/7/004.

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15

Li, Huiyong, Hongxu Jiang, Bo Li, and Miyi Duan. "Reflection Reduction on DDR3 High-Speed Bus by Improved PSO." Scientific World Journal 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/257972.

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The signal integrity of the circuit, as one of the important design issues in high-speed digital system, is usually seriously affected by the signal reflection due to impedance mismatch in the DDR3 bus. In this paper, a novel optimization method is proposed to optimize impedance mismatch and reduce the signal refection. Specifically, by applying the via parasitic, an equivalent model of DDR3 high-speed signal transmission, which bases on the match between the on-die-termination (ODT) value of DDR3 and the characteristic impedance of the transmission line, is established. Additionally, an improved particle swarm optimization algorithm with adaptive perturbation is presented to solve the impedance mismatch problem (IPSO-IMp) based on the above model. The algorithm dynamically judges particles’ state and introduces perturbation strategy for local aggregation, from which the local optimum is avoided and the ability of optimization-searching is activated. IPSO-IMp achieves higher accuracy than the standard algorithm, and the speed increases nearly 33% as well. Finally, the simulation results verify that the solution obviously decreases the signal reflection, with the signal transmission quality increasing by 1.3 dB compared with the existing method.

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16

Jeon, Jung, and Kang. "Software-Based Adaptive Protection Control Against Load Mismatch for a Mobile Power Amplifier Module." Electronics 8, no. 11 (2019): 1226. http://dx.doi.org/10.3390/electronics8111226.

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A closed-loop protection method for a radio frequency (RF) power amplifier (PA) module applicable to mobile handsets has been introduced. The load impedance of the PA was adaptively sensed by an embedded impedance detector which was digitally controlled and the system adjusted PA power using a feedback circuit to keep the PA safe based on a load mismatch detection. For verification, a two-stage hetero junction bipolar transistor (HBT) PA module for handsets was fabricated and tested against load mismatch. Measurement results showed that the technique could help PA survive at a 0.5V larger collector bias voltage condition than when the technique was not applied for the same mismatch condition with an acceptable RF performance degradation at nominal condition.

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17

Kong, Soon Cheol, and Young Wan Choi. "Bandwidth Enhancement of Traveling-Wave Photodetector by Impedance Mismatch." Japanese Journal of Applied Physics 42, Part 1, No. 5A (2003): 2711–14. http://dx.doi.org/10.1143/jjap.42.2711.

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18

Hartley, N. J., C. Zhang, X. Duan, et al. "Dynamically pre-compressed hydrocarbons studied by self-impedance mismatch." Matter and Radiation at Extremes 5, no. 2 (2020): 028401. http://dx.doi.org/10.1063/1.5130726.

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19

Awal, Md Rabiul, Muzammil Jusoh, Muhammad Syarifuddin Yahya, et al. "ACOUSTIC WAVE PROPAGATION IN HIGH SCALE IMPEDANCE MISMATCH MEDIUMS." IIUM Engineering Journal 22, no. 2 (2021): 1–9. http://dx.doi.org/10.31436/iiumej.v22i2.1563.

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A finite element analysis of acoustic propagation in a multilayered medium is presented in this paper. A circular transmitter (diameter 14 mm, thickness 3 mm) and a rectangular receiver (20×10×0.5 mm3) are set to detect the variations in the propagation pattern. A complex medium (70×40×60 mm3) composed of skin, fat, muscle, bone and liquid is designed in a simulated environment. A scale of frequencies (10 kHz to 2 MHz) is applied to trace the impact on the propagation pattern as well. It is found from the analysis that fat and liquid layers affect the acoustic propagation the most (-69 dB), which results in a significant drop in the received sound pressure level at the receiving end. Again, other than skin and fat layers, low frequencies (less than 1 MHz) are more beneficial in terms of sound pressure level. However, higher frequencies contribute to lower displacements at the receiving end, which will cause less power potential as well. ABSTRAK: Analisis elemen terhingga bagi penyebaran akustik dalam medium berlapis dibentangkan dalam kajian ini. Pemancar bulat (diameter 14 mm, ketebalan 3 mm) dan penerima segi empat tepat (20 × 10 × 0.5 mm3) diatur bagi mengesan perubahan pola penyebaran. Medium kompleks (70 × 40 × 60 mm3) yang terdiri daripada kulit, lemak, otot, tulang dan cecair direka dalam persekitaran simulasi. Skala frekuensi (10 kHz hingga 2 MHz) digunakan bagi mengesan corak penyebaran. Dapatan kajian menunjukkan bahawa lapisan lemak dan cecair mempengaruhi penyebaran akustik (-69 dB), yang mengakibatkan penurunan mendadak tahap penerimaan tekanan bunyi di hujung penerima. Selain lapisan kulit dan lemak, frekuensi rendah (kurang dari 1 MHz) adalah lebih berguna dari segi tahap tekanan suara. Walau bagaimanapun, frekuensi lebih tinggi menyebabkan kurang anjakan di hujung penerima, sekaligus mengurangkan potensi daya tenaga.

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20

Lee, Wei Chen, and Hill Wu. "Computer-Aided Analysis and Measurement of an Interconnection System." Advanced Materials Research 308-310 (August 2011): 2279–85. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.2279.

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The electrical characteristics of an interconnection system, which include impedance, insertion loss, and return loss, can greatly affect its performance as the signal speed increases. The objective of this research was to understand the discrepancy between the computer-aided analysis and measurement results of an interconnection system, so that a more accurate prediction of the electrical characteristics of this system can be made during the design phase. It was discovered that in both the time and frequency domain the computer-aided analysis results were consistent with the measurement results. Given these conclusions the simulation model was modified to improve the impedance mismatch within the interconnection system. It was found that by properly designing the antipad, the impedance mismatch can be greatly reduced.

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21

Rathod, Vivek T. "A Review of Acoustic Impedance Matching Techniques for Piezoelectric Sensors and Transducers." Sensors 20, no. 14 (2020): 4051. http://dx.doi.org/10.3390/s20144051.

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The coupling of waves between the piezoelectric generators, detectors, and propagating media is challenging due to mismatch in the acoustic properties. The mismatch leads to the reverberation of waves within the transducer, heating, low signal-to-noise ratio, and signal distortion. Acoustic impedance matching increases the coupling largely. This article presents standard methods to match the acoustic impedance of the piezoelectric sensors, actuators, and transducers with the surrounding wave propagation media. Acoustic matching methods utilizing active and passive materials have been discussed. Special materials such as nanocomposites, metamaterials, and metasurfaces as emerging materials have been presented. Emphasis is placed throughout the article to differentiate the difference between electric and acoustic impedance matching and the relation between the two. Comparison of various techniques is made with the discussion on capabilities, advantages, and disadvantages. Acoustic impedance matching for specific and uncommon applications has also been covered.

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22

Wang, Yi, Han Tang, Wen Li Chen, Xing Zhe Hou, Hong Liang Sun, and Kai Bo Luo. "Research on the Measurement of Household Appliance Impedance Characteristic." Advanced Materials Research 986-987 (July 2014): 1574–78. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1574.

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Impedance of power line channel is the most important factor for power line communication. All kinds of household appliances randomly connect or disconnect from the network, which give rise to impedance variation on power line channel. The mismatch of impedance would reduce the performance of the signal transmission. The power network is mixed with lines and loads. In order to investigate the main factors that affect power network impedance, this paper proposed a method to measure the impedance of active household appliances. Some household appliances are measured with this method, and the result shows that this method can measure the impedance effictively, which helps the study on the impedance charicteristics.

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23

Liu, Cong, Xiao-dong Xu, Xiao-jun Liu, and Christ Glorieux. "Tunable acoustic couplers for two fluids with large impedance mismatch." Applied Physics Express 7, no. 6 (2014): 067302. http://dx.doi.org/10.7567/apex.7.067302.

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24

Wiśniewski, Piotr, Marta Burzańska, and Krzysztof Stencel. "The Impedance Mismatch in Light of the Unified State Model." Fundamenta Informaticae 120, no. 3-4 (2012): 359–74. http://dx.doi.org/10.3233/fi-2012-767.

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25

Dickie, L. O., and Jan Farrell. "The transition from High School to College: An impedance mismatch?" Physics Teacher 29, no. 7 (1991): 440–45. http://dx.doi.org/10.1119/1.2343380.

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26

Medeiros, Eduardo, Thomas Magesacher, Per Odling, et al. "Modeling Alien-Line Impedance Mismatch in Wideband Vectored Wireline Systems." IEEE Communications Letters 18, no. 9 (2014): 1527–30. http://dx.doi.org/10.1109/lcomm.2014.2341551.

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27

Degen, Thomas, and Heinz JÄckel. "Continuous Monitoring of Electrode--Skin Impedance Mismatch During Bioelectric Recordings." IEEE Transactions on Biomedical Engineering 55, no. 6 (2008): 1711–15. http://dx.doi.org/10.1109/tbme.2008.919118.

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28

Ando, K., S. Takahashi, J. Ieda, et al. "Electrically tunable spin injector free from the impedance mismatch problem." Nature Materials 10, no. 9 (2011): 655–59. http://dx.doi.org/10.1038/nmat3052.

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29

Campillo, A. L., J. W. P. Hsu, and Garnett W. Bryant. "Local imaging of photonic structures: image contrast from impedance mismatch." Optics Letters 27, no. 6 (2002): 415. http://dx.doi.org/10.1364/ol.27.000415.

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30

Weiner, M. M. "Noise factor of receiving system with arbitrary antenna impedance mismatch." IEEE Transactions on Aerospace and Electronic Systems 24, no. 2 (1988): 133–40. http://dx.doi.org/10.1109/7.1046.

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31

Liu, Lianxi, Shaopu Gao, Junchao Mu, and Zhangming Zhu. "A Low Power and Low Current-Mismatch Charge Pump with Dynamic Current Compensation." Journal of Circuits, Systems and Computers 28, no. 12 (2019): 1920007. http://dx.doi.org/10.1142/s021812661920007x.

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A novel low power charge pump (CP) that minimizes the mismatch between the charging and the discharging currents is proposed in this paper. The switching circuit with dynamic current compensation is used to reduce the power consumption of the proposed CP. In addition, precise current replication which makes use of the resistors and the low offset operational amplifiers (OTA) can enable a reduction in current mismatch caused by process mismatch. Meanwhile, the high output impedance can reduce the current mismatch caused by the channel length modulation effect. Based on the 0.18[Formula: see text][Formula: see text]m deep-Nwell CMOS process, the proposed CP can reduce the overall power consumption by 56% compared with the CP without current compensation, reduce the current mismatch caused by process mismatch to less than 0.9% and reduce the current mismatch caused by the channel length modulation effect to less than 0.01% over the output voltage ranging from 0.3 to 1.5[Formula: see text]V with 1.8[Formula: see text]V supply.

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Křen, Petr, Vojtech Pálinkáš, Pavel Mašika, and Miloš Vaľko. "Effects of impedance mismatch and coaxial cable length on absolute gravimeters." Metrologia 54, no. 2 (2017): 161–70. http://dx.doi.org/10.1088/1681-7575/aa5ba1.

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33

Arantes, A., and V. Anjos. "Coherent heat transport in 2D phononic crystals with acoustic impedance mismatch." Modelling and Simulation in Materials Science and Engineering 24, no. 3 (2016): 035017. http://dx.doi.org/10.1088/0965-0393/24/3/035017.

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Gu, Lin Qiang. "Theoretical Analysis and Experimental Research of the Absorption Property of a Variable Cross-Section Diffsorber." Advanced Materials Research 838-841 (November 2013): 2262–66. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.2262.

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The internal impedance and radiation impedance of a variable cross-section diffsorber were calculated, when adding bandage to the nozzles of tubes of diffsorber, or using non-linear sound resistance to provide appropriate additional internal resistance, the diffsorber will become an excellent sound absorber. Without bandage, the absorption coefficient of the testing sample is larger than 0.7 during 100Hz-2000Hz, and exceed 1 during 500Hz-800Hz; with bandage, the absorption coefficient of the testing samples is no less than 0.8 during 250Hz-4000Hz, and is above 1 during 250Hz-2000Hz. The performance of absorption begins to reduce from 5000Hz to higher frequency due to the mismatch of internal impedance and radiation impedance.

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35

Vasjanov, Aleksandr, and Vaidotas Barzdenas. "Reduced-Reflection Multilayer PCB Microstrip with Discontinuity Characterization." Electronics 9, no. 9 (2020): 1473. http://dx.doi.org/10.3390/electronics9091473.

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In the era of technology and communication, printed circuit boards (PCBs) can be found in a myriad of devices—from ordinary household items, to state of the art custom metrology equipment. Different types of component for wireless communications are available and come in various packages, supplied by multiple manufacturers. The signal landpads for some high-frequency connectors and components, encapsulated in larger packages, are usually wider than the controlled impedance trace, thereby introducing unwanted impedance mismatch and resulting in signal reflections. The component land pad and microstrip width a discrepancy issue can be found in both complex high-density industrial devices and system-level academic research papers. This paper addresses the topic of compensating discontinuities, introduced by signal pads, which are wider than the target impedance microstrip, characterizes the difference between the compensated and uncompensated microstrip with discontinuity, and proposes a generalized guideline on compensating for the introduced impedance change in multilayer PCBs. The compensation method is based upon carefully designing the stackup of the PCB allowing for a reference plane cutout under the discontinuity to even out the impedance mismatch. A 6-layer PCB with IT180A dielectric material containing three structures has been manufactured and characterized using an Agilent E8363B vector network analyzer (VNA). A 4–12 dB improvement in S11 response in the whole frequency range up to 10 GHz, compared to that when no compensation has been applied, was observed.

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36

Suárez, Almudena, Franco Ramírez, and Sergio Sancho. "Prediction of odd-mode instabilities under output mismatch effects." International Journal of Microwave and Wireless Technologies 9, no. 6 (2017): 1305–15. http://dx.doi.org/10.1017/s1759078717000885.

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A methodology is presented to predict odd-mode instability in power amplifiers under output mismatch effects, as in the case of amplifiers connected to an antenna. This kind of instability is often observed in multi-device configurations, due to their symmetry properties. Unlike the single-ended situation, there is a cancellation of odd multiples of the oscillation frequency at the circuit output, so there is no impact of the load-impedance values at the sideband frequencies. The odd-mode instability only depends on the impedance terminations at the fundamental frequency and its harmonic terms, and can only be detected within the circuit unstable loop, instead of the antenna-connection terminals. The possible unstable modes are related with the eigenvectors of an outer tier conversion matrix accounting for the symmetry properties of the circuit topology. Under sufficient low-pass filtering of the amplifier output network, the analysis parameters can be limited to the magnitude and phase of the reflection coefficient at the fundamental frequency. This analysis involves a computationally efficient graphical technique to detect potential instabilities and a bifurcation-detection method to determine the instability boundaries in the Smith chart. The two main types of instability from periodic regime are considered, respectively associated with incommensurable and subharmonic oscillations. Results have been validated through pole-zero identification and experimental measurements.

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37

Krat, N. M. "Vector network analyzer usage at calibration of delay in satellite radio navigation system signal simulators." Spacecrafts & Technologies 4, no. 2 (2020): 116–22. http://dx.doi.org/10.26732/j.st.2020.2.06.

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This article presents a method of vector network analyzer application at the task of global navigation system simulator calibration. Calibrated parameter is internal delay of the radiofrequency signal in simulator. Attention is payed to reducing of calibration uncertainty by means of taking into account the part, which is caused by impedance of simulator and other equipment mismatches. The goal of research is to estimate the non-excluded uncertainty after vector network analyzer measurements’ usage for correction calculation. Measured parameters are the group delay, reflection and transmission coefficients of cable with connectors, and reflection coefficients of simulator and oscilloscope. The goal has been achieved by means of simulation modelling. The main parts of modelling were simulation of vector network analyzer measurements’ and calculation the statistics of the non-excluded uncertainty. As the result, was shown, that if to use vector network analyzer for global navigation system simulator calibration, the part of uncertainty, caused by impedance mismatch, can be reduced in a several times.

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Kim, Dong-Myeong, Dongmin Kim, Hang-Geun Jeong, and Donggu Im. "A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications." Electronics 9, no. 4 (2020): 562. http://dx.doi.org/10.3390/electronics9040562.

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A reconfigurable CMOS inverter-based stacked power amplifier (PA) is proposed to extend impedance coverage, while maintaining an output power exceeding the specific power level under the worst antenna impedance mismatch conditions. The adopted process technology supports multi-threshold metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and therefore, the proposed PA employs high threshold voltage (Vth) MOSFETs to increase the output voltage swing, and the output power under a given load condition. The unit cell of the last PA stage relies on a cascode inverter that is implemented by adding cascode transistors to the traditional inverter amplifier. By stacking two identical cascode inverters, and enabling one or both of them through digital switch control, the proposed PA can control the maximum output voltage swing and change the optimum load Ropt, resulting in maximum output power with peak power added efficiency (PAE). The cascode transistors mitigate breakdown issues when the upper cascode inverter stage is driven by a supply voltage of 2 × VDD, and decrease the output impedance of the PA by changing its operation mode from the saturation region to the linear region. This variable output impedance characteristic is useful in extending the impedance coverage of the proposed PA. The reconfigurable PA supports three operation modes: cascode inverter configuration (CIC), double-stacked cascode inverter configuration (DSCIC) and double-stacked inverter configuration (DSIC). These show Ropt of around 100, 50 and 25 Ω, respectively. In the simulation results, the proposed PA operating under the three configurations showed a saturated output power (Psat) of +6.1 dBm and a peak PAE of 41.1% under a 100 Ω load impedance condition, a Psat of +4.5 dBm and a peak PAE of 44.3% under a 50 Ω load impedance condition, and a Psat of +5.2 dBm and a peak PAE of 37.1% under a 25 Ω load impedance condition, respectively. Compared to conventional inverter-based PAs, the proposed design significantly extends impedance coverage, while maintaining an output power exceeding the specific power level, without sacrificing power efficiency using only hardware reconfiguration.

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Robertson, George, David Ebert, Stephen Eick, Daniel Keim, and Ken Joy. "Scale and Complexity in Visual Analytics." Information Visualization 8, no. 4 (2009): 247–53. http://dx.doi.org/10.1057/ivs.2009.23.

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The fundamental problem that we face is that a variety of large-scale problems in security, public safety, energy, ecology, health care and basic science all require that we process and understand increasingly vast amounts and variety of data. There is a growing impedance mismatch between data size/complexity and the human ability to understand and interact with data. Visual analytic tools are intended to help reduce that impedance mismatch by using analytic tools to reduce the amount of data that must be viewed, and visualization tools to help understand the patterns and relationships in the reduced data. But visual analytic tools must address a variety of scalability issues if they are to succeed. In this paper, we characterize the scalability and complexity issues in visual analytics. We discuss some highlights on progress that has been made in the past 5 years, as well as key areas where more progress is needed.

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SEKIGUCHI, Yoshie, and Hiroko SHOJI. "A Study on How to Overcome the Impedance Mismatch in Project Management." Transactions of Japan Society of Kansei Engineering 9, no. 2 (2010): 187–95. http://dx.doi.org/10.5057/jjske.j11-090520-2.

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Li, Chen-Zhong, Yi-Tao Long, Jeremy S. Lee, and Heinz-Bernhard Kraatz. "Protein–DNA interaction: impedance study of MutS binding to a DNA mismatch." Chem. Commun., no. 5 (2004): 574–75. http://dx.doi.org/10.1039/b314642a.

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Kaushik, T. C., and B. K. Godwal. "Numerical study of the impedance mismatch effect in laser‐irradiated layered targets." Journal of Applied Physics 64, no. 10 (1988): 4889–95. http://dx.doi.org/10.1063/1.342464.

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Grychtol, Bartłomiej, William R. B. Lionheart, Marc Bodenstein, Gerhard K. Wolf, and Andy Adler. "Impact of Model Shape Mismatch on Reconstruction Quality in Electrical Impedance Tomography." IEEE Transactions on Medical Imaging 31, no. 9 (2012): 1754–60. http://dx.doi.org/10.1109/tmi.2012.2200904.

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Yee, Chang Fei, Muammar Mohamad Isa, Azremi Abdullah Al-Hadi, and Mohd Khairuddin Md Arshad. "Techniques of impedance matching for minimal PCB channel loss at 40 GBPS signal transmission." Circuit World 45, no. 3 (2019): 132–40. http://dx.doi.org/10.1108/cw-01-2019-0004.

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Purpose This paper aims to analyze the negative impact of surface mount (SMT) pad and imperfect via structure such as stub, pad, non-functional pad (NFP) and anti-pad on the signal integrity at 40 Gbps transmission on printed circuit board (PCB) due to impedance mismatch or discontinuity. The optimized modeling of via and SMT structures is performed to achieve minimal impedance mismatch and insertion loss less than 10 dB for six-inch full path transmission line between transmitter and receiver on PCB at Nyquist frequency 20 GHz. Design/methodology/approach This work is split into two phases. The first phase involves optimization of via and SMT structures in three-dimensional electromagnetic (3DEM) simulation using Hyperlynx Via Wizard and Keysight EMPro software, respectively, followed by analysis of time domain reflectometry (TDR) and insertion loss (Sdd21). Whereas, in the second phase, full path hybrid mode simulation involving vias for signal layer transition, a 6-inch PCB channel and SMT pads is performed using Keysight ADS software to observe the TDR, Sdd21 and eye diagram at 40 Gbps transmission. Findings Imperfect via and SMT structures have a negative effect on signal reflection and attenuation. The optimized via and SMT minimizes the impedance mismatch by 81 per cent and insertion loss by 4.5 dB, ultimately enlarging the eye diagram opening to achieve minimal data loss at receiver with 40 Gbps transmission. Originality/value The results of original empirical research work on signal integrity analysis that optimizes the PCB channel design to achieve 40 Gbps signal transmission are presented in this study. It serves as a reference guide for high-speed PCB layout design.

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Eskandari, Aref, Jafar Milimonfared, Mohammadreza Aghaei, and Angèle H. M. E. Reinders. "Autonomous Monitoring of Line-to-Line Faults in Photovoltaic Systems by Feature Selection and Parameter Optimization of Support Vector Machine Using Genetic Algorithms." Applied Sciences 10, no. 16 (2020): 5527. http://dx.doi.org/10.3390/app10165527.

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Photovoltaic (PV) monitoring and fault detection are very crucial to enhance the service life and reliability of PV systems. It is difficult to detect and classify the faults at the Direct Current (DC) side of PV arrays by common protection devices, especially Line-to-Line (LL) faults, because such faults are not detectable under high impedance fault and low mismatch conditions. If these faults are not diagnosed, they may significantly reduce the output power of PV systems and even cause fire catastrophe. Recently, many efforts have been devoted to detecting and classifying LL faults. However, these methods could not efficiently detect and classify the LL faults under high impedance and low mismatch. This paper proposes a novel fault diagnostic scheme in accordance with the two main stages. First, the key features are extracted via analyzing Current–Voltage (I–V) characteristics under various LL fault events and normal operation. Second, a genetic algorithm (GA) is used for parameter optimization of the kernel functions used in the Support Vector Machine (SVM) classifier and feature selection in order to obtain higher performance in diagnosing the faults in PV systems. In contrast to previous studies, this method requires only a small dataset for the learning process and it has a higher accuracy in detecting and classifying the LL fault events under high impedance and low mismatch levels. The simulation results verify the validity and effectiveness of the proposed method in detecting and classifying of LL faults in PV arrays even under complex conditions. The proposed method detects and classifies the LL faults under any condition with an average accuracy of 96% and 97.5%, respectively.

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Yadav, Swati, Anil Kumar Gautam, and Binod Kumar Kanaujia. "Design of dual band-notched lamp-shaped antenna with UWB characteristics." International Journal of Microwave and Wireless Technologies 9, no. 2 (2015): 395–402. http://dx.doi.org/10.1017/s1759078715001609.

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To restrict electromagnetic interference at WiMAX (3.3–3.7 GHz) and wireless local area network (WLAN) (5.15–5.825 GHz) bands operating within ultra wide bandwidth (UWB) band, a novel design of lamp-shaped UWB microstrip antenna with dual band-notched characteristics is presented. The proposed antenna is composed of a lamp-shaped radiating patch with two rectangular ground planes on both the sides of the radiator with the gap of 0.57 mm. To improve impedance mismatch at middle frequencies, two triangular strips one at each of the ground plane are added; whereas a rectangular slot is etched in the radiating patch to remove impedance mismatch at higher frequencies of the UWB band. Furthermore, an L-shaped slot in the radiator and two L-shaped slots in the ground plane are used to restrict electromagnetic interference (EMI) at WiMAX and WLAN bands, respectively, without affecting the electrical performance of the UWB antenna. Effects of the key parameters on the frequency range of the notched bands are also investigated. The proposed design shows a measured impedance bandwidth of 12.5 GHz (2.7–14.4 GHz), with the two band-notched bands of 3.0–3.9 and 4.9–5.8 GHz. The antenna is suitable to be integrated within the portable UWB devices without EMI interference at WiMAX and WLAN bands.

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Luo, Qing, Hui Chen, and Guo Yuan Li. "Design and Simulation of Testing Circuit for Radio Frequency Chip." Applied Mechanics and Materials 423-426 (September 2013): 2639–44. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.2639.

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RF technology is widely used in wireless communication. Due to the small size, high density and high frequency, RF IC testing based on ATE faces many challenges. This paper took a LNA chip fabricated by a GaAs process as an example, simulated the test circuit and studied two methods of RF impedance matching by using the software of Agilent ADS. The results show that it solves the impedance mismatch of the input and output ports in RF test, providing the theoretical support to the design and production of RF test board.

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D S, Rajeshwari, P. V Rao, and Ramesh Karmungi. "10Ghz Charge Pump PLL for Low Jitter Applica-tions." International Journal of Engineering & Technology 7, no. 2.12 (2018): 348. http://dx.doi.org/10.14419/ijet.v7i2.12.11349.

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This paper presents design and simulation of charge pump architectures for 10GHz Charge Pump Phase locked Loop. Differential delay cell VCO with symmetric load and Programmable frequency divider are efficiently implemented in loop. Able to achieve Peak jitter of the Divider 10ns, Peak jitter of VCO 205ps at 1GHz.Charge pump is analysed in loop by reduced current mismatch using improved high swing cascode structure including start up circuitand it has low turn ON voltage and high ouput impedance to provide stable voltage.Charge pump results current mismatch less than 0.05%.10GHz DPLL is simulated with 65nm techonology, 1.2V and tsmc foundary model files

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Gurov, E. V., S. S. Uvaysov, A. S. Uvaysova, and S. S. Uvaysova. "Nominal and Actual Values of Inductor and Capacitor Parameters at High Frequencies." Russian Technological Journal 7, no. 4 (2019): 44–53. http://dx.doi.org/10.32362/2500-316x-2019-7-4-44-53.

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Coil inductance and capacitor capacitance depend on overall dimensions, structure, and ambient factors. They do not vary with frequency. Reactive component impedance is determined by inductance or capacitance respectively, if active resistance is not considered. This is true for the frequencies which are significantly lower than the self-resonant frequency of the component. Parasitic parameters contribution increases on approaching the self-resonant frequency. Therefore, the componentʼs actual inductance and actual capacitance on operating frequency are defined. They are provided by manufacturers and differ from the nominal values. The actual values provide more accurate impedance of components near the considered frequency. Significant deviation from the considered frequency can cause impedance mismatch even more than the nominal values can provide. Frequency response of the high-frequency circuits such as analog filters and impedance match networks are determined by components impedance, not the nominal values. Thus, calculated values must be close to the actual values. The purpose of this article is to justify actual values application instead of nominal values.

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Ruzzene, M., and A. Baz. "Control of Wave Propagation in Periodic Composite Rods Using Shape Memory Inserts." Journal of Vibration and Acoustics 122, no. 2 (1999): 151–59. http://dx.doi.org/10.1115/1.568452.

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Longitudinal wave propagation is controlled using shape memory inserts placed periodically along rods. The inserts act as sources of impedance mismatch with tunable characteristics. Such characteristics are attributed to the unique behavior of the shape memory alloy whereby the elastic modulus of the inserts can be varied up to three times as the alloy undergoes a phase transformation from martensite to austenite. With such controllable capability, the inserts can introduce the proper impedance mismatch necessary to impede the wave propagation along the rods. An analytical model is presented to study the attenuation capabilities of the composite rods and to determine the influence of the various design parameters of the inserts that can control the width of the pass and stop-bands. The numerical results demonstrate the potential of shape memory alloys in controlling the dynamics of wave propagation in rods. Furthermore, the obtained results provide a guideline for designing inserts that are capable of filtering out selected excitation frequencies through proper adjustment of the geometry of the inserts as well as their activation strategies. [S0739-3717(00)00102-1]

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