437 research outputs found
A 39-GHz Doherty-Like Power Amplifier with 22-dBm Output Power and 21% Power-Added Efficiency at 6-dB Power Back-Off
© 2024, IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This is the accepted manuscript version of a conference paper which has been published in final form at https://doi.org/10.1109/JETCAS.2024.3351075The design of a Doherty-like power amplifier for millimetre-wave (mm-wave) applications is presented in this work. The designed power amplifier employs a novel symmetrical loadmodulated balanced amplifier (S-LMBA) architecture. This design is advantageous in minimizing the undesired impedance interaction often encountered in the classic LMBA approach. Such interactions are typically due to the use of a non-50 Ω load at the isolation port of the output quadrature coupler. Moreover, magnitude and phase control networks are carefully designed to generate the specific magnitude and phase information for the designed S-LMBA. To demonstrate the proposed ideas, the SLMBA is fabricated in a 45-nm CMOS SOI technology. At 39 GHz, a 22.1 dBm saturated output power (Psat) with a maximum poweradded efficiency (PAE) of 25.7% is achieved. In addition, 1.68 times drain efficiency enhancement is obtained over an ideal Class-B operation, when the designed S-LMBA is operated at 6 dB power back-off. An average output power of 13.1 dBm with a PAE of 14.4% at an error vector magnitude (EVMrms) above -22.5 dB and adjacent channel power ratio (ACPR) of -23 dBc is also achieved, when a 200 MHz single carrier 64-quadratureamplitude- modulation (QAM) signal is used. Including all testing pads, the footprint of the designed S-LMBA is only 1.56 mm2.Peer reviewe
Nonlinear Control of FACTS Controllers for Damping Interarea Oscillations in Power Systems
This paper introduces a new nonlinear control of flexible ac transmission systems (FACTS) controllers for the purpose of damping interarea oscillations in power systems. FACTS controllers consist of series, shunt, or a combination of series-shunt devices which are interfaced with the bulk power system through injection buses. Controlling the angle of these buses can effectively damp low frequency interarea oscillations in the system. The proposed control method is based on finding an equivalent reduced affine nonlinear system for the network from which the dominant machines are extracted based on dynamic coherency. It is shown that if properly selected, measurements obtained from this subsystem of machines are sufficient inputs to the FACTS controllers to stabilize the power system. The effectiveness of the proposed method on damping interarea oscillations is validated on the 68 bus, 16 generator system of the New England/New York network
Reconfigurable Intelligent Surface for Physical Layer Security in 6G-IoT: Designs, Issues, and Advances
Sixth-generation (6G) networks pose substantial security risks because
confidential information is transmitted over wireless channels with a broadcast
nature, and various attack vectors emerge. Physical layer security (PLS)
exploits the dynamic characteristics of wireless environments to provide secure
communications, while reconfigurable intelligent surfaces (RISs) can facilitate
PLS by controlling wireless transmissions. With RIS-aided PLS, a lightweight
security solution can be designed for low-end Internet of Things (IoT) devices,
depending on the design scenario and communication objective. This article
discusses RIS-aided PLS designs for 6G-IoT networks against eavesdropping and
jamming attacks. The theoretical background and literature review of RIS-aided
PLS are discussed, and design solutions related to resource allocation,
beamforming, artificial noise, and cooperative communication are presented. We
provide simulation results to show the effectiveness of RIS in terms of PLS. In
addition, we examine the research issues and possible solutions for RIS
modeling, channel modeling and estimation, optimization, and machine learning.
Finally, we discuss recent advances, including STAR-RIS and malicious RIS.Comment: Accepted for IEEE Internet of Things Journa
Man-in-the-Middle Attack Resistant Secret Key Generation via Channel Randomization
Physical-layer based key generation schemes exploit the channel reciprocity
for secret key extraction, which can achieve information-theoretic secrecy
against eavesdroppers. Such methods, although practical, have been shown to be
vulnerable against man-in-the-middle (MitM) attacks, where an active adversary,
Mallory, can influence and infer part of the secret key generated between Alice
and Bob by injecting her own packet upon observing highly correlated
channel/RSS measurements from Alice and Bob. As all the channels remain stable
within the channel coherence time, Mallory's injected packets cause Alice and
Bob to measure similar RSS, which allows Mallory to successfully predict the
derived key bits. To defend against such a MitM attack, we propose to utilize a
reconfigurable antenna at one of the legitimate transceivers to proactively
randomize the channel state across different channel probing rounds. The
randomization of the antenna mode at every probing round breaks the temporal
correlation of the channels from the adversary to the legitimate devices, while
preserving the reciprocity of the channel between the latter. This prevents key
injection from the adversary without affecting Alice and Bob's ability to
measure common randomness. We theoretically analyze the security of the
protocol and conduct extensive simulations and real-world experiments to
evaluate its performance. Our results show that our approach eliminates the
advantage of an active MitM attack by driving down the probability of
successfully guessing bits of the secret key to a random guess.Comment: 13 pages, 8 figures, 4 table
High efficiency power amplifiers for modern mobile communications: The load-modulation approach
Modern mobile communication signals require power amplifiers able to maintain very high efficiency in a wide range of output power levels, which is a major issue for classical power amplifier architectures. Following the load-modulation approach, efficiency enhancement is achieved by dynamically changing the amplifier load impedance as a function of the input power. In this paper, a review of the widely-adopted Doherty power amplifier and of the other load-modulation efficiency enhancement techniques is presented. The main theoretical aspects behind each method are introduced, and the most relevant practical implementations available in recent literature are reported and discussed
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