| 1. |
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| 2. |
- Abbasi, Muhammad Ali Babar, et al.
(författare)
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Constant-εr Lens Beamformer for Low-Complexity Millimeter-Wave Hybrid MIMO
- 2019
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 67:7, s. 2894-2903
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Tidskriftsartikel (refereegranskat)abstract
- It is well established that the utilization of unused millimeter-wave (mmWave) spectrum is inevitable due to unavailability of required bandwidth in the conventional RF band to support the high data demands of 5G. Large antenna arrays with beamforming capabilities are required to compensate for the high path loss at mmWave frequencies. We are at the verge of a massive mmWave radio front-end deployment, and low-complexity low-cost hardware beamforming solutions are required now at this stage than ever before. In this paper, one such solution is demonstrated and analyzed. A high-performance and low-complexity lens-based beamformer consisting of constant dielectric material ( ϵr ) with antenna feeds is presented for multibeam operation. A prototype is developed based on the classical synthesis approach, and in line with the requirements of mmWave hybrid multiuser multiple-input multiple-output (MU-MIMO) systems. A characterization at 28 GHz is performed wherein an uplink signal-to-noise ratio of user terminals is evaluated with the zero-forcing (ZF) baseband signal processing. Radiation performance of a single-source beamformer is measured in an anechoic environment, and end-to-end ergodic sum spectral efficiency performance is estimated based on the measured data. It is shown that the constant- ϵr -based beamformer solution is simple, yet significantly outperforms conventional antenna array beamformers with analog phase shifter networks, making it a promising candidate for future hybrid massive MIMO systems.
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| 3. |
- Abbasi, Morteza, 1982, et al.
(författare)
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Single-Chip 220-GHz Active Heterodyne Receiver and Transmitter MMICs With On-Chip Integrated Antenna
- 2011
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 59:2, s. 466-478
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the design and characterization of single-chip 220-GHz heterodyne receiver (RX) and transmitter (TX) monolithic microwave integrated circuits (MMICs) with integrated antennas fabricated in 0.1-mu m GaAs metamorphic high electron-mobility transistor technology. The MMIC receiver consists of a modified square-slot antenna, a three-stage low-noise amplifier, and a sub-harmonically pumped resistive mixer with on-chip local oscillator frequency multiplication chain. The transmitter chip is the dual of the receiver chip by inverting the direction of the RF amplifier. The chips are mounted on 5-mm silicon lenses in order to interface the antenna to the free space and are packaged into two separate modules. The double-sideband noise figure (NF) and conversion gain of the receiver module are measured with the Y-factor method. The total noise temperature of 1310 +/- 100K(corresponding to an NF of 7.4 dB), including the losses in the lens and antenna, is measured at 220 GHz with a respective conversion gain of 3.5 dB. The radiated continuous-wave power from the transmitter module is measured to be up to -6 dBm from 212 to 226 GHz. The transmitter and receiver are linked in a quasi-optical setup and the IF to IF response is measured to be flat up to 10 GHz. This is verified to be usable for transmission of a 12.5-Gb/s data stream between the transmit and receive modules over a 0.5-m wireless link. The modules operate with a 1.3-V supply and each consume 110-mW dc power. The presented 220-GHz integrated circuits and modules can be used in a variety of applications, including passive and active imaging, as well as high-speed data communications. To the best of our knowledge, these MMICs are the highest frequency single-chip low-noise heterodyne receiver and transmitter pair reported to date.
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| 4. |
- Abbasi, Morteza, 1982, et al.
(författare)
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Single-Chip Frequency Multiplier Chains for Millimeter-Wave Signal Generation
- 2009
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 57:12, s. 3134-3142
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Tidskriftsartikel (refereegranskat)abstract
- Two single-chip frequency multiplier chains targeting 118 and 183 GHz output frequencies are presented. The chips are fabricated in a 0.1 mu m GaAs metamorphic high electron-mobility transistor process. The D-band frequency doubler chain covers 110 to 130 GHz with peak output power of 5 dBm. The chip requires 2 dBm input power and consumes only 65 mW of dc power. The signal at the fundamental frequency is suppressed more than 25 dB compared to the desired output signal over the band of interest. The G-band frequency sextupler (x6) chain covers 155 to 195 GHz with 0 dBm peak output power and requires 6.5 dBm input power and 92.5 mW dc power. The input signal to the multiplier chain can be reduced to 4 dBm while the output power drops only by 0.5 dB. The unwanted harmonics are suppressed more than 30 dB compared to the desired signal. An additional 183 GHz power amplifier is presented to be used after the x6 frequency multiplier chain if higher output power is required. The amplifier delivers 5 dBm output power with a small-signal gain of 9 dB from 155 to 195 GHz. The impedance matching networks are realized using coupled transmission lines which is shown to be a scalable and straightforward structure to use in amplifier design. Microstrip transmission lines are used in all the designs.
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| 5. |
- Abdulaziz, Mohammed, 1983, et al.
(författare)
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A 10-mW mm-wave phase-locked loop with improved lock time in 28-nm FD-SOI CMOS
- 2019
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 67:4, s. 1588-1600
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 IEEE. This paper presents a millimeter-wave (mm-wave) phase-locked loop (PLL), with an output frequency centered at 54.65 GHz. It demonstrates a mode-switching architecture that considerably improves the lock time, by seamlessly switching between a low-noise mode and a fast-locking mode that is only used during settling. The improvement is used to counteract the increased lock-time caused by cycle-slips that results from using a high reference frequency of 2280 MHz, which is several hundred times the loop bandwidth. Such a reference frequency alleviates the noise requirements on the PLL and is readily available in 5G systems, from the radio frequency PLL. The mm-wave PLL is implemented in a low-power 28-nm fully depleted silicon-on-insulator CMOS process, and its active area is just 0.19 mm 2 . The PLL also features a novel double injection-locked divide-by-3 circuit and a charge-pump mismatch compensation scheme, resulting in state-of-the-art power consumption, and jitter performance in the low-noise mode. In this mode, the in-band phase noise is between-93 and-96 dBc/Hz across the tuning range, and the integrated jitter is between 176 and 212 fs. The total power consumption of the mm-wave PLL is only 10.1 mW, resulting in a best-case PLL figure-of-merit (FOM) of-245 dB. The lock time in low-noise mode is up to 12μs, which is improved to 3μs by switching to the fast-locking mode, at the temporary expense of a power consumption increase to 15.1 mW, an integrated jitter increase to between 245 and 433 fs, and an FOM increase to between-235 and-240 dB.
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| 6. |
- Afsar Doost, Sepideh, 1983, et al.
(författare)
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Digital Predistortion Using a Vector Switched Model
- 2012
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 60:4, s. 1166-1174
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Tidskriftsartikel (refereegranskat)abstract
- Abstract—A switched behavioral model considering memory effects with special focus on ”difficult” amplifier architectures is proposed in this paper. The proposed model is shown to be very simple and linearly identifiable. A digital predistorter based on the proposed model is implemented for a 100–W, 2.6 GHz Doherty power amplifier that has been considered difficult in other reports, and it is shown that the proposed model can succesfully linearize the amplifier. In particular, the proposed model and the digital predistorter is shown to outperform other state-of-the-art models and digital predistorers in terms of computational complexity for a given desired accuracy.
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| 7. |
- Ahmad, Waqas, et al.
(författare)
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CMOS Integrated Remote Antenna Unit for Fiber-Fed Distributed MIMO Systems
- 2017
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 65:1, s. 173-186
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Tidskriftsartikel (refereegranskat)abstract
- A fully integrated remote antenna unit (RAU) intended for fiber-fed distributed multiple-input multiple-output systems is presented. The circuit is designed for narrowband (60 MHz) time-division duplex systems, where an IF over fiber approach is chosen to facilitate the use of low-cost optical components and integrated photodetectors. A novel antenna switch control scheme is introduced, which enables the use of an integrated antenna switch instead of a bulky off chip circulator. The reference frequency signal is distributed in the fiber together with user data and used by a phase-locked-loop-based frequency synthesizer to generate the local oscillator signal inside the RAU, hence synchronizing all RAUs of the distributed antenna system. At an operating frequency of 2.1 GHz, the measured optical-to-electrical conversion gain of the downlink is 71.7 dB, the error vector magnitude is 3.2%, and the adjacent channel leakage ratio is 39.2 dBc at an output power of +3 dBm for a 16-quadrature amplitude modulation (16-QAM) long-term evolution downlink signal. The uplink has a gain of 32.5 dB, a noise figure of 3.5 dB, and an in-band third-order intercept point of -12 dBm. Implemented in a standard 65-nm CMOS process, the complete RAU occupies just 2 mm2 of die area and consumes 146 mW during downlink signal transmission and 122 mW during uplink signal reception.
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| 8. |
- Aksimsek, Sinan, et al.
(författare)
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TEM wave scattering by a step discontinuity on the outer wall of a coaxial waveguide
- 2013
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Ingår i: IEEE transactions on microwave theory and techniques. - : IEEE Press. - 0018-9480 .- 1557-9670. ; 61:8, s. 2783-2791
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the propagation of TEM waves along a coaxial waveguide with a step discontinuity on its outer wall is investigated rigorously by applying the direct Fourier transform and reducing the problem into the solution of a modified Wiener–Hopf equation. The solution for the field terms are determined in terms of an infinite number of unknown coefficients, which satisfy an infinite set of linear algebraic equations. These equations are solved numerically and the effect of area ratio is presented graphically at the end of the analysis. The same problem is also analyzed by applying the mode-matching technique and the results of the two approaches are compared. It is observed numerically that the Wiener–Hopf technique provides a better convergence than the mode-matching technique.
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| 9. |
- Alex-Amor, Antonio, et al.
(författare)
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Glide-Symmetric Metallic Structures With Elliptical Holes for Lens Compression
- 2020
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Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 68:10, s. 4236-4248
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we study the wave propagation in a metallic parallel-plate structure with glide-symmetric elliptical holes. To perform this study, we derived a mode-matching technique based on the generalized Floquet theorem for glide-symmetric structures. This mode-matching technique benefits from a lower computational cost since it takes advantage of the glide symmetry in the structure. It also provides physical insight into the specific properties of Floquet modes propagating in these specific structures. With our analysis, we demonstrate that glide-symmetric structures with periodic elliptical holes exhibit an anisotropic refractive index over a wide range of frequencies. The equivalent refractive index can be controlled by tuning the dimensions of the holes. Finally, by combining the anisotropy related to the elliptical holes and transformation optics, a Maxwell fish-eye (MFL) lens with a 33.33% size compression is designed. This lens operates in a wideband frequency range from 2.5 to 10 GHz.
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| 10. |
- Algaba Brazalez, Astrid, 1983, et al.
(författare)
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Design and Validation of Microstrip Gap Waveguides and Their Transitions to Rectangular Waveguide, for Millimeter-Wave Applications
- 2015
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 63:12, s. 4035-4050
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes the design methodology, experimentalvalidation and practical considerations of two millimeterwave wideband vertical transitions from two gap waveguide versions (inverted microstrip gap waveguide, and microstrip packaged by using gap waveguide) to standard WR-15 rectangular waveguide. The experimental results show S11 smaller than -10 dB over relative bandwidths larger than 25% and 26.6% when Rogers RO3003 and RO4003 materials are used respectively. The vertical transition from standard microstrip line packaged by a lid of pins to WR-15, shows measured return loss better than 15 dB over 13.8% relative bandwidth. The new transitions can be used as interfaces between gap waveguide feed-networks for 60 GHz antenna systems, testing equipment (like Vector Network Analyzers) and components with WR-15 ports, such as transmitting/receiving amplifiers. Moreover, the paper documents the losses of different gap waveguide prototypes compared to unpackaged microstrip line and Substrate Integrated Waveguide (SIW). This investigation shows that in V-band the lowest losses are achieved with inverted microstrip gap waveguide.
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