Three-stage Power Research Articles

A Ka-Band Doherty Power Amplifier in a 150 nm GaN-on-SiC Technology for 5G Applications

This paper presents a Ka-band three-stage power amplifier for 5G communications, which has been implemented in a 150 nm GaN-on-SiC technology and adopts a Doherty architecture. The amplifier is made up of a 50 Ω input buffer, which drives a power splitter, thanks to which it delivers its output power to the two power amplifier units of the Doherty topology, namely the main and auxiliary amplifier. Finally, the outputs of the two power amplifiers are properly arranged in a current combining scheme that enables the typical load modulation of the Doherty architecture, alongside allowing power combining at the final output. The proposed amplifier achieves a small signal gain of around 30 dB at 27 GHz, while providing a saturated output power of 32 dBm, with a power-added efficiency (PAE) as high as 26% and 18% at peak and 6 dB output power back-off, respectively.

A 4.5–8.5 GHz GaAs power amplifier with high in-band flatness

This paper presents a 4.5–8.5 GHz three-stage power amplifier(PA) fabricated in a 0.5 μm GaAs process. The PA adopts gain compensation technology with gain flatness and power transmission in the broadband. Furthermore, the size of the pHEMT is optimized to strike a balance among linearity, power-added efficiency (PAE) and the area. The measurement results show that the proposed PA has a gain flatness of 22.6 ± 0.8 dB with good input and output VSWR, the output saturation power is of 25 dBm and the corresponding power added efficiency is greater than 32% over the whole operating frequency band. This proposed PA has better broadband gain flatness and power characteristics compared to the conventional cascaded PA. The chip size of the PA is 2.475 mm × 0.9 mm, including all DC and RF pads.

Three-Stage Power Supply System Model for a Wearable IoT Device for COVID-19 Patients.

During the current crisis caused by the COVID-19 pandemic, Wearable IoT (WIoT) health devices have become essential resources for remote monitoring of the main physiological signs affected by this disease. As well as sensors, microprocessor, and wireless communication elements are widely studied, the power supply unit has the same importance for the WIoT technology, since the autonomy of the system between recharges is of great importance. This letter presents the design of the power supply system of a WIoT device capable of monitoring oxygen saturation and body temperature, sending the collected data to an IoT platform. The supply system is based on a three-stage block consisting of a rechargeable battery, battery charge controller, and dc voltage converter. The power supply system is designed and implemented as a prototype in order to test performance and efficiency. The results show that the designed block provides a stable supply voltage avoiding energy losses, which makes it an efficient and rapidly developing system.

Area-Efficient 28-GHz Four-Element Phased-Array Transceiver Front-End Achieving 25.2% Tx Efficiency at 15.68-dBm Output Power

An area-efficient 28-GHz four-element phased-array transceiver front-end (TRx FE) is proposed in this article. Transmitter/receiver (T/R) switch, phase shifter (PS), and power combining/splitting network all use customized coupler-based structures to replace area-consuming quarter-wavelength ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4) transmission line (T-line) structures. In Tx mode, a three-stage power amplifier (PA) is designed by cascading a class-AB predriver amplifier, a deep class-AB driver amplifier, and a class-A output amplifier for high output power. In Rx mode, a two-stage low noise amplifier (LNA) is designed with a 3-bit resistive adjusting load for high dynamic range of input power. A coupler is adopted in the variable gain amplifier (VGA) to achieve constant phase during gain adjustment. The proposed TRx FE is fabricated in a 40-nm CMOS process. Measurement results show that output 1-dB compression point (OP1dB) of 14.99 dBm and saturated output power (OPsat) of 15.68 dBm with 25.2% power efficiency are achieved in each Tx element. In each Rx element, noise figure (NF) of 4.54 dB, input 1-dB compression point (IP1dB) of −10.15 dBm, and maximum gain of 26.3 dB with 56.1-mW power consumption are realized. The gain range of Rx/Tx mode is 9.9–26.3 dB/24.2–44.6 dB with a resolution of 0.3 dB and phase variation less than 2° at 28 GHz. Thanks to the area-efficient coupler-based structures, the phased-array TRx FE occupies an area of 0.42 mm2 for each element and 0.084 mm2 for total area of combiner/splitter, achieving high area efficiency for Ka-band phased-array TRx FEs.

CuBr Laser Pumped by a Three-Stage Power Supply

CuBr Laser Pumped by a Three-Stage Power Supply

CuBr laser pumped by a three-stage power supply

CuBr laser pumped by a three-stage power supply

Analysis and Design of Power Electronic Transformer for Smart Grid Application

With the development of smart grid and energy Internet, power electronic transformer has become one of the key equipment in power system. Its characteristic research and structure design have become a hot topic in related research fields. In order to take into account, the access of traditional AC motor system and renewable energy system, a three-stage power electronic transformer simulation model based on Simulink platform is built in this paper, and the key characteristics are analyzed and verified. With the application of power electronic transformer, the AC voltage can be adjusted quickly, and the AC / DC interface can be taken into account in the transmission system.

Room temperature, nanosecond, 60 mJ/pulse Fe:ZnSe master oscillator power amplifier system operating at 3.8-5.0 µm.

We report on a RT gain-switched Fe:ZnSe master oscillator power amplifier (MOPA) system tunable over 3.8-5.0 µm pumped by radiation of Er:YAG laser operating at 2.94 µm. The mechanically Q-switched Er:YAG laser with output energy up to 220 mJ was used as a pump source for a master oscillator and three-stage power amplifier. The maximum output energies in 200 ns pulses exceeded 60, 56, and 48 mJ at 4.4, 4.3, and 4.1 µm, respectively, under 220 mJ of pump energy. The extraction energy efficiencies were measured to be 25, 30, and 40% at the first, second, and third stages, respectively.

Distortion mitigation for 100 and 250 MHz discrete supply modulation of a three-stage K-band MMIC PA

AbstractThis paper presents a high-efficiency linear GaN K-band transmitter for broadband high peak-average power ratio (PAPR) signals. A GaN MMIC 18.5–24 GHz three-stage power amplifier with over 4 W peak output power, 20 dB saturated gain, and 40% peak PAE is supply-modulated with a four-level discrete dynamic supply GaN MMIC. For 100 MHz signals with ${\rm PAPR}\gt 10\, {\rm dB}$, we demonstrate an average efficiency improvement from 14 to 20% with a simultaneous linearity improvement in noise power ratio (NPR) from 23 to 26 dB through a shaping function focused on gain linearization. For 250 MHz signal bandwidth, there is no observed degradation in NPR and the efficiency is improved by 5 percentage points. For discrete supply modulation, the switching transients between levels are experimentally investigated for wideband signals.

A Novel Power Spectrum-Based Sequential Tracker for Time-Variant Radio Propagation Channel

Cluster tracking is a mainstream approach for the study of time-variant channel characteristics. In the paper, we propose a power spectrum based sequential tracker (PSBST) to compensate for the disadvantages of existing cluster tracking algorithms. The proposed tracker identifies clusters via simple three-stage power spectrum processing. Furthermore, fuzzy c-means (FCM) algorithm is incorporated to separate clusters considering the overlapped clusters which may appear in the power spectrum. In terms of tracking, we implement Kalman filter to sequentially predict candidate ranges of tracked clusters in consecutive snapshots and simultaneously a novel gradient-based histogram of power (GBHOP) method is devised to determine the evolution of clusters. We also investigate the performance of the tracker by synthetic channel simulation. It demonstrates high accuracy and less computational time compared with the results derived from the existing cluster tracking algorithms. Besides, we verify applicability of the tracker by analyzing the field measurement conducted in vehicle-to-everything (V2X) scenario, and preliminary statistical characteristics for intra-cluster and inter-cluster parameters can be readily obtained in the sequel.

A V-Band Power Amplifier With 23.7-dBm Output Power, 22.1% PAE, and 29.7-dB Gain in 65-nm CMOS Technology

This article presents a V-band three-stage power amplifier (PA) fabricated in 65-nm CMOS technology with remarkable performances of output power, efficiency, and power gain. A cascode amplifier is proposed to optimize the power performances at millimeter-wave (mm-wave). A current-combining radial structure transformer power combiner with a low impedance transmission line is used to combine four differential power cells efficiently and to further improve the output power. Meanwhile, two common-source (CS) amplifiers are cascaded to achieve high power gain. The measured results of the proposed PA demonstrate the saturated output power ( $P_{\mathrm {sat}}$ ) of 23.7 dBm, output 1-dB compression point ( OP 1 dB) of 19.9 dBm, peak power added efficiency (PAE) of 22.1%, and 29.7-dB power gain at 60 GHz with only 0.653-mm2 chip size.

Influence Factors of Stability on Offshore HVDC Transmission Systems

Sun, L.; Liu, H., and Bian, D., 2019. Influence factors of stability on offshore HVDC transmission systems. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 561–571. Coconut Creek (Florida), ISSN 0749-0208.Offshore wind energy has been recognized as one of the most promising renewable energy resources available. High-voltage direct current (HVDC) appears to be the most viable option for solving the transmission of the large amount of energy over long distances of the integration of offshore wind farms. However, HVDC with large capacity is continually being commissioned, the coupling and interaction between the sending-side and receiving-side AC systems interconnected by large-scale DC links are becoming significant. Power impacts caused by DC commutation failures (CFs) may lead to power fluctuation on two-area interconnected power system. If the DC capacity is large enough, the stability of power system may be threatened. In this paper, using equal area rule, the stability limit of DC transmission capacity is analyzed. In addition, based on the power system three-stage power allocation theory after power impacts, the power fluctuation of the two-area AC/DC parallel transmission system caused by CFs was represented as the impulse response of a two-order linear system model. The key factors affecting the stability limit are furtherly discussed. Then the results are verified using advanced digital power system simulator (ADPSS) for the two-area IEEE-39 network model for AC/DC parallel transmission. Finally, the control measures for improving the stability of AC/DC parallel transmission system were put forward.

W-Band power amplifier with high output power and power-added efficiency in 90 nm CMOS

This paper reports a three-stage four-way power amplifier for 94 GHz image radar systems in 90 nm CMOS technology. The PA comprises a common-source (CS) input stage and a CS gain stage with wideband π-match input, inter-stage and output networks, followed by a four-way CS output stage using miniature dual-Y divider and combiner. Inductive shunt–shunt feedback technique is used at both the input and gain stages to enhance gain, which in turn leads to a higher output power (Pout) and power-added efficiency (PAE). At each branch’s input terminal (i.e. the drain terminal of the parallel CS output stage), the dual-Y current combiner can convert the serial RL load to the optimal load impedance (corresponds to the optimal Pout and PAE) of the output stage transistors. At 94 GHz, the PA achieves power gain of 16.5 dB, Pout of 16.5 dBm, and PAE of 18.3%, one of the best results ever reported for a W-band PA in 90 nm CMOS. The excellent performance of the CMOS PA indicates that it is suitable for 94 GHz image radar transceivers.

Overview of Three-Stage Power Converter Topologies for Medium Frequency-Based Railway Vehicle Traction Systems

With new developments in power electronics and semiconductor devices, there has been an increasing interest in the adoption of power electronic traction transformer (PETT) topologies in railways, mainly for the purpose of mass and volume reduction against conventional topologies. Apart from traction transformers, examples include isolation circuits for on-board auxiliary power units (APU) and even 750 VDC, 110 VDC and lower voltage (e.g., 72 VDC) battery chargers. Special attention has been given to the more mature technology of three-stage (ac–dc–MFac–dc) configurations with intermediate medium frequency ac (MFac) links. In contrast to conventional architectures, it becomes difficult to select a suitable multistage topology of power electronics for the design of complex traction systems with advanced requirements. The power electronics utilized in different configurations have a significant effect on performance, efficiency, power quality (harmonics and stability), and cost indicators for the whole system, making the selection and design process more complex. The objective of this paper is to provide a clear overview of proposed topologies with special emphasis on the power electronic architectures utilized in three-stage PETT systems particularly for railway traction systems and on-board APUs. With regards to the listed range of possible architectures provided to the reader, key characteristics, such as total semiconductor (switches and diodes) count numbers per module per phase, input/output voltage levels, operating frequencies, and the most commonly used resonant networks, are summarized and discussed.

Optimization for Postearthquake Resilient Power System Capacity Restoration Based on the Degree of Discreteness Method

The occurrence of a natural disaster such as a strong earthquake affects not only the capacity of a city’s power supply system but also the normal operation of other lifeline systems. An urban emergency power supply system is used to manage the power supply restoration with the consumers divided into three types based on their impact and importance during a power failure. In this study, a power supply system equipped to meet the requirements of different restoration level facilities and enable the restoration of power after the occurrence of an earthquake was developed. A three‐stage power restoration curve was formulated based on the postearthquake recovery process. The relative importance factors of consumers can be calculated with a normalization model based on membership degree. These relative importance factors were then combined with the postearthquake recovery capabilities of each consumer to calculate the overall recovery capability and equilibrium degree of the urban power system. Using the two foregoing indicators, the power supply recovery level of the power system after an earthquake was quantitatively analyzed, and the power supply scheme of the consumers with different power supply guarantee types was rationally optimized.

Fully Integrated Single-Chip 305–375-GHz Transceiver With On-Chip Antennas in SiGe BiCMOS

A fully integrated single-chip transceiver (TRX) with on-chip antennas for transmitting and receiving signals within a continues frequency range from 305 to 375 GHz is presented. The radio-frequency (RF) and local oscillator signals are generated using a wideband push–push voltage-controlled oscillator, a three-stage power amplifier, and a frequency doubler. A heterodyne receiver using a fundamental mixer converts the received RF signal to an intermediate frequency (IF) signal, which drives an IF amplifier. Additionally, a divide-by-64 frequency divider is integrated to provide a low-frequency output for measurement purposes and to enable later the addition of a phase-locked loop for frequency stabilization and synthesis. A 130-nm silicon–germanium BiCMOS process with $f_t/f_{\max}$ = 250 GHz/370 GHz is used. The TRX chip is wire bonded to a printed circuit board and a TPX (Polymethylpentene) lens is placed on top of the chip for focusing the radiation. At a frequency of 343 GHz, the measurements show an effective isotropic radiated power of 18.4 dBm, a phase noise of $-$ 79 dBc/Hz@1 MHz, and an IF conversion gain of 28 dB. The obtained tuning bandwidth of 70 GHz is the highest reported so far for fully integrated TRXs.

A 55‐W high efficiency unbalanced three‐stage Doherty power amplifiers for various output power back‐offs

AbstractHigh efficiency unbalanced three‐stage Doherty power amplifiers (DPA) for input signals with various peak to average power ratios (PAPR) are presented. The amplifier uses three GaN devices of equal size. The output power back‐off (OPBO) at the efficiency peak of the amplifier can be extended and reduced according to the input signals with various PAPR. This is achieved by adjusting the impedances of the λ/4 impedance transformers at the individual amplifier output stages in the three‐stage DPA without the use of additional circuitries and by changing the impedance matching circuit at the input stages of the amplifiers. The current of the individual amplifiers in the three‐stage DPA is calculated according to the PAPR of the input signals. The impedances of the λ/4 impedance transformers are determined by the current ratio for the main, first peaking, and second peaking amplifiers and are implemented by microstrip lines. 55 W unbalanced three‐stage DPAs for extended and reduced OPBO are designed and fabricated to be operated at the frequency of 1810 MHz.

Design and analysis of wideband eight-way SIW power splitter for mm-wave applications

High-performance, wideband three-stage power splitters based on substrate integrated waveguide (SIW) are presented. Broadband-tapered microstrip transitions are used for feeding the SIW structures, which provide 7.5 GHz bandwidth from 21.5 to 29 GHz with return loss below −20 dB. In addition, various T junctions are tuned, not only to provide broadband performance up to mm-wave frequencies but also offer low-phase and amplitude imbalance when cascaded in multistage 1 × 8 splitters. 1 × 4 and 1 × 2-T junctions are adjusted through parametric analysis to provide wide bandwidth of 3.5 GHz at 24.5 GHz and −15 dB reflection coefficient. The optimal microstrip transitions and T junctions are used to design a broadband, eight-way power splitter with 15 dB return loss from 23.0 to 26.4 GHz and phase and amplitude imbalance of ±2.5° and ±0.8° dB, respectively. Furthermore, optimum positions of all inductive posts in terms of guided wavelength are also provided for assisting the direct design of mm-wave, high-performance power splitters.

Three-stage power system restoration methodology considering renewable energies

This is a study of a combined load restoration and generator start-up procedure. The procedure is structured into three stages according to the power system status and the goal of load restoration. Moreover, for each load restoration stage, the proposed algorithm determines a load restoration sequence by considering renewable energy such as solar and wind park to achieve objective functions. The validity and performance of the proposed algorithm is demonstrated through simulations using IEEE-39 network.

High power generation of adaptive laser beams in a Nd:YVO4 MOPA system

We report efficient power scaling of the laser output with an adaptive beam profile from an Nd:YAG dual-cavity master oscillator using a three-stage end-pumped Nd:YVO4 amplifier. We succeed in the fast switching of an excited laser mode by modulating an acousto-optic modulator loss in a dual-cavity master oscillator, thereby achieving temporal modulation of the output beam profile. The outputs from the master oscillator are amplified via a three-stage power amplifier yielding 36.6, 40.5, and 45.4 W of the maximum output at 116.8 W of incident pump power for the transverse electromagnetic, Laguerre–Gaussian, and quasi-top-hat beam, respectively. The prospects for further power scaling and applications via the dual-cavity master-oscillator power-amplifier (MOPA) system are considered.