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

On Secrecy Performance of MISO SWIPT Systems With TAS and Imperfect CSI

In this paper, a multiple-input single-output (MISO) simultaneous wireless information and power transfer (SWIPT) system, including one base station (BS) equipped with multiple antennas, one desired single-antenna information receiver (IR), and N (N > 1) single-antenna energy-harvesting receivers (ERs) is considered. Assuming that the information signal to the desired IR may be eavesdropped by ERs if ERs are malicious, we investigate the secrecy performance of the target MISO SWIPT system when imperfect channel state information (CSI) is available and adopted for transmit antenna selection at the BS. Considering that each eavesdropping link experiences independent but not necessarily identically distributed Rayleigh fading, the closed-form expressions for the exact and the asymptotic secrecy outage probability, and the average secrecy capacity are derived and verified by simulations. Furthermore, the optimal power splitting factor is derived for each ER to realize the tradeoff between the energy harvesting and the information eavesdropping. Our results reveal the impact of the imperfect CSI on the secrecy performance of MISO SWIPT systems in the presence of multiple wiretap channels

Exploration and Mining Learning Robot of Autonomous Marine Resources Based on Adaptive Neural Network Controller

To study the autonomous learning model of the learning robot for marine resource exploration, an adaptive neural network controller was applied. The motion characteristics of autonomous learning robots were identified. The mathematical model of the multilayer forward neural network and its improved learning algorithm were studied. The improved Elman regression neural network and the composite input dynamic regression neural network were further discussed. At the same time, the diagonal neural network was analysed from the structure and learning algorithms. The results showed that for the complex environment of the ocean, the structure of the composite input dynamic regression network was simple, and the convergence was fast. In summary, the identification method of underwater robot system based on neural network is effective

Optimization Study on Fluids for the Gravity-Driven Organic Power Cycle

The organic Rankine cycle (ORC) is efficient in using low-grade heat energy, while low pump efficiency and high pump leakage are usually serious problems. A gravity-driven organic power cycle (GDOPC) uses gravity instead of a pump to pressurize working fluid and has the potential to avoid problems associated with the pump. A theoretical method is used to study the performance and suitability of several fluids for GDOPC. The results show that the flow efficiency in high vertical pipes and the pump efficiency determine whether GDOPC gives better performance than ORC or not. When R245fa is selected as working fluid and evaporating temperature is 62 °C, specific energy of GDOPC (flow efficiency is 80%) is 2.5% higher than that of ORC (pump efficiency is 60%). The improvement degree of specific energy and the liquid column height increase with increasing evaporating temperature. R1234yf and R227ea give good performance with specific energy of 4.84 kJ/kg and 4.82 kJ/kg, respectively, while they need a liquid column as much as 76.55 m and 45.65 m, respectively. Although R365mfc and cyclopentane do not give the most excellent cycle performance, they need liquid column height as low as 9.04 m and 10.88 m, respectively. Fluid with low saturated pressure and high density may need low liquid column height and has the advantage to be used in practical applications

Investigation on the Pinch Point Position in Heat Exchangers

The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out by theoretical method. The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties. In most cases, the pinch point locates at the bubble point for the evaporator and the dew point for the condenser. However, the pinch point shifts to the supercooled liquid state in the near critical conditions for the evaporator. Similarly, it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser. It even can shift to the working fluid entrance of the evaporator or the supercritical heater when the heat source fluid temperature is very high compared with the absorbing heat temperature. A wrong position for the pinch point may generate serious mistake. In brief, the pinch point should be founded by the iterative method in all conditions rather than taking for granted

Experimental Investigation on Performance of an Organic Rankine Cycle System Integrated with a Radial Flow Turbine

An experimental method is used to investigate the performance of a small-scale organic Rankine cycle (ORC) system which is integrated with a radial flow turbine, using 90 °C hot water as a heat source. The considered working fluids are R245fa and R123. The relationship between cycle performance and the operation parameters is obtained. With constant condensing pressure (temperature), the outlet temperature of the hot water, the mass flow rate of the hot water and the evaporator heat transfer rate increase with increasing evaporating pressure. Turbine isentropic efficiency decreases and transmission-generation efficiency increases with rising evaporating pressure. In the considered conditions, the maximum specific energy is 1.28 kJ/kg, with optimal fluid of R245fa and an optimal evaporating temperature of 69.2 °C. When the evaporating pressure (temperature) is constant, the outlet temperature of the cooling water increases, and the mass flow rate of the cooling water decreases with increasing condensing pressure. Turbine isentropic efficiency increases and transmission-generation efficiency decreases with the rise of condensing pressure. In the considered conditions, the maximum specific energy is 0.89 kJ/kg, with optimal fluid of R245fa and an optimal condensing temperature of 29.1 °C. Turbine efficiency is impacted by the working fluid type, operation parameters and nozzle type

Performance analysis of a zeotropicmixture (R290/CO_2) for trans-critical power cycle

Low critical temperature limits the application of CO 2 trans-critical power cycle. The binary mixture of R290 2 has higher critical temperature. Using mixture fluid may solve the problem that subcritical CO 2 is hardly condensed by conventional cooling water. In this article, theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of 200 °C. The results indicated that the problem that CO 2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO 2 . Variation trend of outlet temperature of thermal oil in supercritical heater with heating pressure is determined by the composition of the mixture fluid. Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290. There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure