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A radio frequency quadrupole (RFQ) has been constructed as a front accelerator for a rare isotope accelerator facility. The RFQ has two power couplers that are operated simultaneously for high power operation to accelerate from proton to uranium. Coaxial transmission lines have been adopted to connect each power coupler to the 80 kW solid state power amplifier(SSPA) which is consisted with combiners, circulators and 5 kW unit amplifiers. In this study, the coupling to the cavity with two power couplers was investigated for the failure of RF power units. Moreover, the operation scenario of the RFQ linac was also presented in considering the availability. [ABSTRACT FROM AUTHOR]

This paper details the motivation and the status of a new satellite mission, which targets the in-orbit verification of a wide band satellite communication link, operating in the high millimeter-wave regime at 71–76 GHz. Under ideal weather conditions, data rates over 15 Gb/s in complex modulation formats are expected to be demonstrated in-orbit, while data rates over 6 Gb/s are still expected under adverse atmospheric and weather conditions. The scientific payload, hosted by a 6U-CubeSat platform, comprises a high-performance W-band transmitter with GaN-based solid state power amplifiers, an InGaAs-based low-noise receiver and a modern FPGA-based digital processing unit, realizing arbitrary waveform generation functionality and 4k image/video storage. The ground terminal employs a highly directive Cassegrain antenna with coarse GNSS and fine multi-mode RF tracking and a low-noise receiver together with an integrated high-speed digital processing and storage unit. [Display omitted] • Motivation and status of the high throughput novel communication satellite • In-orbit verification and demonstration of data downlink at 71–76 GHz • State-of-the-Art analog frontend payload in InGaAs and GaN technology • Miniaturized computationally powerful FPGA-based payload computer • Evaluation of the wave propagation impairments and signal degradation • Challenges of the RF tracking through multi-mode tracking [ABSTRACT FROM AUTHOR]

This paper presents a 28-GHz wideband power amplifier (PA) with the dual-pole tuning superposition technique for 5G applications in a 55-nm RF CMOS. The PA employs a four-stage pseudo-differential structure together with the two-way combining approach to enhance the power gain. Transmission-line transformer (TLT) matching networks are proposed in the PA for not only performing the impedance matching, but also tuning the peak gains of the four stages to two different pole frequencies. The dual-pole frequencies are eventually superposed to improve the bandwidth and gain. Meanwhile, techniques of capacitance neutralization, load-pulling, and power combination are adopted for power stages to improve the output power and efficiency significantly. Biased at the class-A mode by a supply voltage V DD of 1.5 V, the fabricated PA exhibites the measured peak small-signal gain (S 21) of 21.9 dB and power gain (PG) of 20 dB at 28 GHz. The measured performances of saturated output power (P sat) of 15.4–16.8 dBm, output 1-dB compression point (OP 1dB) of 12–13.5 dBm, and power added efficiency (PAE P1dB) of 11%–14.7% are achieved over the bandwidth of 24–30 GHz, featuring wideband linearity/PAE. The chip occupies a core area of 1.5 × 0.6 mm2. • A 28-GHz wideband PA with the dual-pole tuning superposition technique is presented in a 55-nm CMOS for 5G communication. • TLT matching networks are proposed in the PA which performs the impedance matching and improves the bandwidth and gain. • Capacitance neutralization, load-pulling, and power combination are adopted for power stages to improve the output power and efficiency. • The measured results show peak S21 of 21.9 dB and power gain of 20 dB at 28 GHz. The chip occupies a core area of 1.5 × 0.6 mm2. • The measured performances of P sat of 16.8 dBm, OP 1dB of 13.5 dBm, and PAE P1dB of 14.7% are achieved at 28 GHz. [ABSTRACT FROM AUTHOR]

In order to enhance spectrum utilization and decrease transmission delay, the 6th generation mobile networks (6G) system adopts full-duplex (FD) mode. Simultaneous operation of the same frequency inevitably causes the receiver to receive the signal sent by the transmitter, leading to serious nonlinear self-interference due to the nonlinear distortion generated by the power amplifier (PA). This paper proposes hybrid layer structures SW-GRU-TPA for the implementation of digital self-interference cancellation (SIC), combined with Sliding Window (SW), Gated Recurrent Unit (GRU), and Temporal Pattern Attention (TPA). The model can not only effectively utilize the influence of historical information on the signal, but also capture the spatial and temporal dependencies in the data to fit the nonlinear characteristics of the PA and the delay effect in multipath transmission. Meanwhile, by utilizing the L 1 norm model pruning, the model parameters can be optimized, leading to improved processing efficiency. The model is verified using two methods: injection and antenna reception. Compared to the SW-GRU model with Attention Mechanism (AM), the Interference Cancellation Ratio (ICR) of injection and antenna increases by 3.13 dB and 2.01 dB, respectively. When the TPA is compressed by 42.17%, the ICR of injection and antenna decreases by 1.58% and 2.6%. [ABSTRACT FROM AUTHOR]

This article presents a simple and effective method for designing a dual-band power amplifier (PA). A microstrip coupled-line bandstop filter (BSF) is cascaded with a broadband PA, thus a notched band can be obtained in the wide operating band, realizing a dual-band characteristic of the PA. The simplified real frequency technique (SRFT) is employed to derive a broadband input matching networks covering the requisite frequency band. Appropriate fundamental impedance and second harmonic impedance matching are achieved at the ideal region of the Smith chart. For validation, an experimental prototype is fabricated and tested using a commercial GaN transistor Cree's CGH40010F. The proposed dual-band PA is operated at 1.95–2.4 GHz and 2.65–3.1 GHz, with 61%–71% measured power-added efficiency (PAE) and 40.5–41.5 dBm of measured output power. [ABSTRACT FROM AUTHOR]

Digital pre-distortion (DPD) technology is currently the dominant technology employed to compensate for the nonlinearity of power amplifiers (PAs). Recently, PA modeling methods based on machine learning have attracted much attention. However, the traditional model still suffers from the defects of long modeling time or insufficiently high modeling accuracy. To solve this problem, the global representative point selection (GRPS) algorithm and the randomized SVD (RSVD) algorithm based on the least squares twin support vector regression (LSTSVR) model are introduced. The GRPS algorithm is first used to select a specific number of globally representative points from all the data to construct the support vector set. Then the RSVD algorithm is used to perform a low-rank approximation to the target kernel matrix. The modeling performance of the proposed approach is compared with the existing model using different communication signals, and the results show that the proposed model can improve the modeling accuracy and reduce the modeling time. Further, a pre-distortion experimental platform is established, and the proposed model is used to pre-distort the Class F PA and the Doherty PA respectively, which proves that the proposed model has a good nonlinear correction effect. [ABSTRACT FROM AUTHOR]

The next generation of Ring Imaging CHerenkov detectors in high energy physics experiments may use SiPMs as photon sensing elements. This upgrade is necessary to achieve greater detector granularity and speed, however SiPMs need to be cooled down to cryogenic temperatures to detect single photons in high-radiation environments and avoid being overwhelmed by the presence of "dark signals". It is therefore necessary to study and characterize SiPM models in dedicated campaigns, using a custom-built amplifying chain that can also operate in an extended temperature range, between 80 K and 300 K, for detector characterization purposes. The proposed amplifier configuration consists of two amplifying stages and achieves low jitter values (< 10 − 20 ps RMS ) thanks to the low electronic noise and the high amplifier bandwidth. The circuit achieves a signal bandwidth of 500 MHz < BW < 1 GHz , a phase margin of approximately 45° and a power consumption of about 65 − 135 mW. The amplifier prototype unit can be adjusted to cover the considered temperature range and still achieve low jitter values. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surfaces (RISs) have recently gained significant attention for improving reliability in vehicular communications. However, ensuring reliable communication between far-distance vehicles remains a challenge. This work investigates an RIS-aided vehicular ad hoc network (VANET) in a road section where the distance between vehicles is too large for a single roadside unit (RSU) to provide reliable communication. We propose a novel RIS architecture where several RIS panels are connected by cables and each is equipped with a power amplifier. We then optimize vehicle power and RIS reflection coefficients to maximize the minimum bit rate of the VANET. Due to the non-convex nature of the formulated problem, we use fraction programming (FP) to reformulate it into a convex form, allowing solution using tools like CVX which is a MATLAB-based modeling system for convex optimization. The reformulated problem is then decoupled into subproblems. Block coordinate descent (BCD) is employed to optimize all variables alternately and obtain the joint optimal solution. Additionally, the alternating direction method of multipliers (ADMM) ensures that the phase shift of each reflecting element remains a unit vector. Finally, semidefinite relaxation (SDR) is used to solve the boolean quadratically constrained problem. Simulation results demonstrate the effectiveness of the proposed method and confirm that our architecture outperforms conventional approaches. [ABSTRACT FROM AUTHOR]

The RF power amplifier chip, as the core component of RF front-end, often experiences high temperature accumulation during operation due to its small size and high power characteristics, which can easily affect the electrical performance and service life of the amplifier. However, traditional EDA design software can only simulate a single characteristic and cannot achieve collaborative optimization of multiple physical fields. Therefore, this article uses MATLAB as the main control platform and combines ADS, HFSS, and ANSYS to build a multiphysics collaborative simulation and optimization platform. It can automatically parameterize modeling and perform circuit, electromagnetic, thermal, and stress collaborative simulation and optimization on power amplifier chips, effectively improving the design efficiency of power amplifier chips while ensuring their electrical performance and reliability. This article presents an automatic modeling and collaborative simulation optimization of a K-band GaN HEMT MMIC power amplifier chip based on this platform. The simulation results of the optimized power amplifier chip show that its maximum temperature is reduced by 40% and deformation is reduced by 50% in saturated state while remaining good RF characteristics. This proves the practicality of the platform and its engineering significance for power amplifier chip design. • We use MATLAB as the main control program and build a multiphysics collaborative simulation and optimization platform by means of API with ADS, HFSS and ANSYS, effectively ensuring power amplifier chips' electrical performance and reliability. • Multiphysics collaborative simulation and optimization platform uses MATLAB as the main optimization controller to carry out system level optimization, effectively improving the design and optimization efficiency of power amplifier chips. • This multiphysics collaborative simulation and optimization platform can also be used for the design and reliability evaluation of other RF circuits, providing a new tool for the research and development of RF integrated circuits. [ABSTRACT FROM AUTHOR]

This paper presents a multi-switch-controlled multi-mode transceiver front end (TRFE) designed for the 2.4-GHz industrial–scientific–medical (ISM) band, with a particular focus on enhancing the linearity of the transmit/receive switch (TRSW) on the antenna side. Considering the distinct power levels in the RX/TX paths, the TRSW is designed to be asymmetric. This design not only elevates IP -0.1dB by over 50 % compared to the conventional symmetric topology, but also absorbing its function into the input matching network (IMN) of the low noise amplifier (LNA), thereby minimally impacting the noise figure (NF) of the RX chain. For the TX path, the high-pass component of the power amplifier (PA) output matching network (OMN) is repurposed, with a singular inductor being redeployed to serve as an inductive ESD safeguard. Moreover, the driving stage employs a passive gain-boosting technique, which elevates the gain by 3 dB compared to the traditional cascode structure. For verification, this TRFE is fabricated in 0.18-μm CMOS with a die size of 1.53 mm2. It achieves a NF of 2.4 dB and a RX gain of 16.7 dB under a 3.3-V supply. A TX gain of 26.2 dB and a saturation output power of 23.3 dBm with a peak power-added efficiency (PAE) of 38.8 % are also demonstrated. [ABSTRACT FROM AUTHOR]

This letter studies omnidirectional beamforming based on a uniform rectangular array (URA) for common message broadcasting. Noticing a subtle yet important fact that the whole (θ , φ) -angular domain maps to a circular region in the (u , v) -domain, we propose to optimize the beamforming weights to make the power radiation as even as possible only in the circle. The resultant scheme, termed as quasi-omnidirectional beamforming (quasi-OBF), yields near-omnidirectional radiation while the peak-to-average power ratio (PAPR) of the array elements is significantly lower than the state-of-the-art approach, which can help improve the energy efficiency of the power amplifiers (PAs) driving the antenna array. We also prove that even constraining the beamforming weights to be unimodular for maximizing the energy efficiency of the PAs, the omnidirectional beamforming is asymptotically achievable by convergence in L 2 as the number of the URA elements increases to infinity. The theoretical results are corroborated by the numerical simulations. • Optimizing within a circular frequency domain of URA achieves flatter beampattern. • Unimodular weights can achieve asymptotically omnidirectional beampattern. • More antennas facilitate flatter beampatterns. [ABSTRACT FROM AUTHOR]

In this paper, a Doherty power amplifier (DPA) is proposed consisting of class-E as the main branch and class-D as the auxiliary power amplifier (PA). Past matching network is applied in the proposed DPA to control the output impedance and reduce its deviation from matching point, which provides improved bandwidth characteristic. The use of λ/4 lines for inductor modeling, employing power divider and input/output matching networks based on micro-strip stubs result in size reduction of proposed DPA, better isolation of the ports and lower return loss. The proposed Doherty structure is based on class-E in main branch and class-D in auxiliary branch, which provides high efficiency, and high output power in 2.7–3.5 GHz frequency band. The proposed DPA has drain efficiency of 65.4% and the gain of 18.6 dB in P-1dB point (27 dBm input power) where in this point, the output power is 45.87 dBm. In the saturation region, the output power of 48.6 dBm and drain efficiency of 93.7% can be obtained in the proposed DPA as shown in simulation results. • High efficiency of class-E PA in main branch to achieve high drain efficiency and power added efficiency. • Extension of linearity region of proposed DPA using class-D in the auxiliary branch. • Effective power divider for proposed DPA to highlight the power efficiency. • Using λ/4 micro-strip lines for inductor modeling and input/output matching network. • Past matching network for impedance phase control and bandwidth extension of the proposed structure. [ABSTRACT FROM AUTHOR]

When using shortwave PAs for long-distance communication, the output of the PA will have a series of in-band and out-of-band spectral interference problems introduced by intermodulation distortion (IMD) and harmonic distortion because of the nonlinearity and memory effect of the PA. The existing methods of harmonic cancellation include the use of filter banks for harmonic cancellation and digital harmonic cancellation. Based on the Volterra series, the harmonic cancellation generalized memory polynomial (HC-GMP) model is proposed. Compared with the generalized memory polynomial (GMP) model and the memory polynomial (MP) model, the HC-GMP model has better harmonic cancellation capability. The experimental data show that the HC-GMP model mitigates the second and third harmonics of the PA's output signal by about 5 dB and 10 dB, respectively, compared to the GMP model. • The existing methods of harmonic cancellation include the use of filter banks for harmonic cancellation and digital harmonic cancellation. Based on the Volterra series, the harmonic cancellation generalized memory polynomial (HC-GMP) model is proposed. • Compared with the generalized memory polynomial (GMP) model and the memory polynomial (MP) model, the HC-GMP model has better harmonic cancellation capability. • The experimental data show that the HC-GMP model mitigates the second and third harmonics of the PA's output signal by about 5 dB and 10 dB, respectively, compared to the GMP model. [ABSTRACT FROM AUTHOR]

• Output power of DC Er:Yb amplifiers can be controlled via 1064 nm signal injection. • 1σ SD of the output power reached 29 µW for long-term measurements. • The proposed technique provides a 7.6 kHz output power stabilization bandwidth. We present a novel technique for all-optical stabilization of the output power of telecom band amplifiers based on double-clad (DC) erbium-ytterbium (Er:Yb) doped fibers. The proposed method relies on the utilization of the undesirable energy back-transfer effect which occurs in DC Er:Yb active fibers. A feedback loop is built based on a low-power 1064 nm laser, which is coupled into the Er:Yb fiber along with the 1550 nm seed. The auxiliary 1 µm signal partially extracts the Yb-ion energy, altering the gain at the design wavelength. The stabilization technique was verified for two types of fibers, to demonstrate the feasibility of our approach regardless of the type of DC Er:Yb fiber used, its characteristics, and the amplifier configuration. A long-term stability improvement by a factor of 117 was achieved, reaching a deviation of 0.8 µ W, for 100 s integration time. [ABSTRACT FROM AUTHOR]

This paper presents a driving amplifier (DA) utilizing the proposed asymmetric broadside coupled line. In contrast to conventional coupled line, the balun devised with proposed asymmetric coupled line and enhanced wideband balance compensation technique is utilized, thereby achieving wideband impedance matching and mitigating insertion loss. Additionally, the utilization of the lossy over-neutralization technique substantially enhances the power gain of amplifiers operating in the upper millimeter-wave band (150 GHz–300 GHz). The DA is fabricated utilizing a 40-nm CMOS process without aluminum layers. The fabricated amplifier demonstrates a compact total area of 0.135 mm 2 (0.031 λ 2), with a core area of 0.027 mm 2 (0.0061 λ 2). It achieves a high gain of 19.4 dB, high power of 11.05 dBm, and high power-added efficiency (PAE) of 11.05% at 160 GHz. Moreover, both the 3-dB power gain bandwidth and the 3-dB saturated power bandwidth extend from 132 GHz to 170 GHz, covering a bandwidth of 38 GHz. This configuration underscores the robust performance of the DA in the upper millimeter-wave band. [ABSTRACT FROM AUTHOR]

This paper presents a novel Doherty power amplifier (DPA) structure that employs two equal-cell transistors with an extended high-efficiency range. It is illustrated that the DPA high-efficiency range can be extended by employing a novel coupler-based network through introducing different impedance at the isolation port, which can improve the back-off range. The corresponding theoretical architecture of the proposed coupled DPA is constructed with design parameters. The load modulation effect with different circuit parameters are also analyzed, and DPA performance in different back-off range can be obtained. To validate the proposed architecture, a symmetrical coupled DPA with a high-efficiency range of around 9 dB is designed at 2 GHz. Under the continuous-wave(CW) signal, the fabricated DPA achieves saturated output power of 44.2 dBm and saturated drain efficiency (DE) of 65%. At 8.5 dB back-off, DE of 51.2% can be obtained with a gain of 14 dB. When driven by a 20 MHz Long Term Evolution (LTE) signal with 8 dB peak to average power ratio (PAPR), the measured adjacent channel power ratio (ACPR) keeps better than −20 dBc without linearization. The measurement results well conform to the theoretical analysis and simulation results. [ABSTRACT FROM AUTHOR]

This paper proposes a Doherty power amplifier (DPA) design method based on harmonic tuning and output combining network (OCN) optimization to extend the power back-off (PBO) range. Firstly, based on the optimal harmonic load impedance, a harmonic tuning optimization method is used to design the harmonic tuning network of the amplifiers, effectively improving the efficiency at saturation and PBO. Secondly, the fundamental output matching network and the post-matching network are considered as an OCN. The S -parameters of the OCN are calculated and utilized in the DPA design. To further expand the PBO range, the carrier load impedance at PBO is determined by considering the relationship between PBO range and reflection coefficient. Finally, a multi-objective evolutionary algorithm combined with the theory of solution set is used to optimize the OCN design, simplifying the design process of the output matching network. For verification, a high-efficiency DPA operating at 1.68 GHz with a large PBO range of 9.5 dB is designed and measured. Results indicate that the proposed DPA achieves a saturated output power greater than 44 dBm, with a peak efficiency of up to 75.2%. The efficiencies are 68.5% and 61.0% at 6 and 9.5 dB back-off powers, respectively. [ABSTRACT FROM AUTHOR]

This paper proposes a generalized design methodology for extending the bandwidth and output back-off range of an equal-cell Doherty power amplifier (EC-DPA). The parameters of the EC-DPA combiner are derived based on pre-defined asymmetrical voltage and nonlinear current profiles. It is illustrated that the design parameters of the EC-DPA can be expressed as a function of the combining load. Then, the combining load can be optimized to extend the bandwidth of the proposed EC-DPA. As a validation, an 1.4–2.1 GHz EC-DPA with extended output back-off range is implemented in this paper. Under a continuous-wave (CW) signal excitation, the fabricated EC-DPA achieves a maximum output power of 42.6–43.8 dBm, a saturation drain efficiency (DE) of 50.2%–70.2% and a 10 dB back-off DE of 45.2%–53.7% over 1.4–2.1 GHz. Moreover, under the excitation of a 20 MHz modulated signal with a peak-to-average power ratio (PAPR) of 8.0 dB, the measured adjacent channel leakage ratios (ACLRs) of the fabricated EC-DPA changes from −36.2 dBc to −25.5 dBc at the lower band and from −34.6 to −23.8 dBc at the upper band over 1.4–2.1 GHz when the average output power is 35.0 dBm. [ABSTRACT FROM AUTHOR]

In this article, an in-depth analysis is presented for the first time by considering the impact of the input nonlinearity caused by gate-source capacitance (C gs) on the performance and broadband design of extended series of continuous modes (ESCMs) power amplifiers (PAs). The conclusion of the analysis shows that the drain current waveforms of ESCMs will be altered, resulting in the overlapping region with the voltage waveform and theoretical efficiency becoming a function of the nonlinear factor γ under the influence of input nonlinearity. As a result, compared to the traditional ESCMs PAs, the introduction of nonlinear factor γ has given rise to a wider load design space and source second-harmonic manipulation space, which can achieve bandwidth expansion while reducing the design complexity of input and output matching networks. Subsequently, this conclusion was verified by using a commercially available 10W gallium nitride (GaN) device from Cree to design wideband high-efficiency PAs. The measured results show that in the target frequency band from 0.55 to 3.55 GHz, a drain efficiency of 60.5%–71.5 % and a gain of 9–12 dB can be obtained at a saturated output power of 39–42 dBm. [ABSTRACT FROM AUTHOR]

This article presents an in-depth exploration of the circuit architecture and design approach for broadening the high-efficiency range of dual-mode symmetrical Doherty power amplifiers (DPAs). To enhance performance across a broader spectrum, a modified dual-mode load modulation network (LMN) is introduced, leveraging the reciprocal gate bias configuration to support an expanded high-efficiency range exceeding 6 dB across two distinct operational bands. To corroborate the efficacy of our proposed dual-mode symmetrical DPA architecture, we designed and constructed a prototype power amplifier (PA) utilizing commercially available GaN transistors. The implemented PA demonstrates exceptional performance, achieving two distinct Doherty operation bands, specifically 1.85–2.0 GHz in Mode I and 1.5–1.55 GHz in Mode II. Remarkably, the high-efficiency range is extended to 8 dB in both bands. Furthermore, the drain efficiency achieves levels of 48.5%–51.8% in Mode I and 47.7%–50.4% in Mode II at 8 dB back-off, with a saturated output power exceeding 43 dBm. [ABSTRACT FROM AUTHOR]

This paper theoretically analyzes the network phase solution space under Doherty, Outphasing, and hybrid modes. A dual-input wideband Doherty-Outphasing power amplifier (DOPA) design method is proposed. This method can ensure that the output back-off (OBO) amount is further increased based on the OBO amount of Doherty power amplifier. To prove the reliability of the proposed method, a hybrid DOPA power amplifier in the band of 1.7–2.4 GHz with an OBO amount of 12 dB is designed. The experimental results also show that the output power of the hybrid DOPA is 48.6–49.5 dBm in the band of 1.7–2.3 GHz, and the saturation efficiency is 57%–63%. The efficiency at 12 dB, 9 dB and 6 dB OBO is 42%–50%, 46%–59% and 50%–63% respectively. The digital pre-distortion correction is carried out at 1.8, 2.1 and 2.3 GHz frequency points, and the adjacent channel power ratio is lower than -47.7 dBc. Simulation and experiment results can verify the effectiveness and correctness of the proposed method. To the best of our knowledge, it is the first time to achieve such a wide bandwidth to the hybrid DOPA with the proposed design method. [ABSTRACT FROM AUTHOR]

This article introduces an efficiency-enhanced filtering power amplifier (FPA) design that exhibits a dual-band response and excellent stopband rejection. This design effectively minimizes the need for numerous microwave components in the dual-band radio frequency front-end, leading to a smaller circuit footprint and reduced signal loss. The recommended approach entails the utilization of an output matching network (OMN), comprising a harmonic control network (HCN) and a dual-band band-pass filter (BPF) to provide dual‐band impedance matchings and filtering responses simultaneously. Specifically, the HCN draws inspiration from the concept of complementary split ring resonators (CSRRs) to efficiently manage undesirable harmonic content. Additionally, the incorporation of the dual-band BPF serves the dual purpose of facilitating dual-band operation while maintaining the desired filtering characteristics. To prove the concept, a dual-band FPA was developed, utilizing a commercially available 10 W GaN HEMT. This FPA was designed to operate efficiently within two distinct frequency ranges. Our achieved findings reveal that within the lower frequency band, spanning from 1.5 to 2.1 GHz, the FPA achieves its maximum Drain Efficiency (DE) at 69.4 %. Concurrently, it demonstrates an output power reaches a notable value of 39.7 dBm at a specific frequency of 1.55 GHz. When transitioning to the upper frequency band, covering the range of 3.0 to 4.0 GHz, the FPA consistently maintains its peak DE at 80.3 %, accompanied by an output power of 42 dBm, this time at 3.6 GHz. [ABSTRACT FROM AUTHOR]

An automatic in-situ technique for thermal resistance measurement based on an electrical method is proposed in this paper. In contrast to the conventional thermal resistance measurement circuits of the electrical method, this method involves direct measurement of the thermal resistance of GaN high-electron-mobility transistor (HEMT) devices in an operating circuit by introducing a well-matched radio-frequency switching circuit into the operating circuit. The advantage of this method is that the thermal resistance can be measured periodically on the in-situ device without changing the electrical characteristics of the device. Based on this result, the cooling curve of the HEMT device in the power amplifier (PA) circuit is collected and the thermal resistance characteristics of the HEMT are determined via the structure function method. The purpose of this paper is to successfully obtain the thermal resistance of in-situ devices through an automatic in-situ measurement circuit of thermal resistance, and to verify the feasibility of periodic detection of thermal resistance of in-situ devices. [ABSTRACT FROM AUTHOR]

In this paper, two methods for accurate behavioral modeling of circuits applicable to the power amplifiers (PAs) are proposed. Firstly, an X-band PA based on WIN's 0.15 μm GaAs pHEMT process is presented. Taking this PA as an example, a modeling method based on the Particle Swarm Optimization algorithm optimized Back-Propagation Artificial Neural Network (PSO-BP ANN) is proposed and verified to realize a multi-output PA behavioral model. To solve the problem of increasing error caused by the inconsistency of basic property (i.e. dimension) between the output nodes of the BP ANN, the Non-dominated Sorting Genetic Algorithm-II optimized BP ANN (NSGA–II–BP ANN) modeling method is proposed. Finally, the two modeling methods proposed above are compared in terms of modeling accuracy, and the accuracy of NSGA–II–BP ANN is further verified based on the circuit measured results. [ABSTRACT FROM AUTHOR]

This paper presents a Ka -band power amplifier with a compression-state large-signal matching approach in 130-nm CMOS SOI technology. The amplifier employs a quad-branch topology based on zero-degree power combiners/splitters, with each branch comprising two differential stages, each containing four stacked FETs. With a compression-state large-signal matching approach, this design achieves the saturated output power (P sat) of 27.6 dBm with 14.1 % peak power added efficiency (PAE), output 1-dB compression point (OP 1dB) of 20.1 dBm at 35 GHz, according to electromagnetic simulation (EM) results. Additionally, it exhibits a peak gain of 39.2 dB at 33 GHz and a 3-dB bandwidth across 32–38 GHz. Offering a low-cost solution suitable for phased array radars and satellite communications. • In this paper, a cascaded series power amplifier with a Psat of 27.6 dBm and a 1 dB bandwidth of 32–36 GHz is proposed. • The compression-state large-signal matching approach improves the power output capability of the stacked unit. • Low-loss passive devices are designed in this paper. [ABSTRACT FROM AUTHOR]

In this paper, we present the design and implementation of an efficient inverse Class- F (Class- F − 1) power amplifier (PA) using a compact Harmonic control unit (HCU). The HCU is implemented using a two-transmission line network that precisely controls the second and third harmonic impedances. The small size of the HCU reduces the circuit's overall layout and enables easy implementation. Tuning lines are utilized to better match the source and load impedances at the input and output. The design is substantiated by a PCB-fabricated prototype over a frequency range of 1 GHz to 2 GHz. For a bandwidth of 600 MHz (1200–1800 MHz), the proposed PA has a measured power-added efficiency (PAE) and output power of over 65% and 40 dBm, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we propose and experimentally demonstrate a D-band photonics-aided long-distance and large-capacity wireless transmission system. Based on photonics-aided millimeter wave communication technology, advanced equipment, and an advanced digital signal processing (DSP) algorithm, we have successfully realized the wireless transmission of a 15G baud PS-16QAM signal in the D-band of 4.6 km. At the transmitting end, the probability shaping (PS) technique and the truncated probability shaping (TPS) technique are introduced to alleviate the nonlinear impairment introduced by the photoelectric/electro-optic (OE/EO) conversion. Meanwhile, a high-gain power amplifier (PA) and a pair of self-designed polytetrafluoroethylene (PTFE) lenses are used to achieve long-distance transmission. At the receiving end, the Volterra nonlinear equalization (VNE) algorithm based on the multiple-input-multiple-output (MIMO) structure is deployed to compensate the residual I/Q imbalance impairment and nonlinear impairment. By utilizing this advanced equipment and DSP algorithms, a 4.6 km wireless transmission with a net bit rate of 41.7 Gb/s has been successfully realized over D-band, and its bit error rate (BER) is below the 25 % soft-decision forward error correction (SD-FEC) threshold of 4.2 × 10−2. The product of the net bit rate and wireless transmission distance has reached a record 41.7 Gb/s × 4.6 km = 191.8 Gb/s·km. As far as we know, this is the first experimental demonstration of a net rate exceeding 40 Gb/s in a D-band long-distance transmission system. [ABSTRACT FROM AUTHOR]

• The first kilowatt-level wavelength tunable Raman fiber laser is demonstrated based on triple-clad passive fiber. • Up to 1135.7 W Raman signal at 1124.3 nm is obtained with a conversion efficiency of 71.8 %. • The wavelength of the kilowatt Raman signal can be tuned from 1119.8 nm to 1137.2 nm. Raman fiber laser (RFL), due to its unique advantages of wide tuning range, free of photon darkening, and low quantum defect, is becoming an important kind of high power laser source. In this manuscript, we demonstrate a kilowatt-level wavelength tunable RFL. It employs a typical master oscillator power amplifier configuration. The seed laser is a homemade tunable random RFL. The Raman gain fiber is a section of triple-clad passive fiber. At an optimal Raman fiber length of 150 m based on numerical simulations, 1135.7 W Raman signal at 1124.3 nm can be achieved under pump power of 1543 W, corresponding to a power conversion efficiency of 71.8 %. Moreover, by tuning the wavelength of seed laser, kilowatt-level Raman signal continuously tunable from 1119.8 nm to 1137.2 nm is demonstrated. To the best of our knowledge, this is the first kilowatt-level wavelength tunable RFL ever reported. [ABSTRACT FROM AUTHOR]

This article presents a Doherty-like Reconfigurable Load Modulated Power Amplifier (R-LMBA) topology, which enables a broadband 6-/12-dB power back-off (PBO) reconfiguration by rearranging the bias voltages of the sub-amplifiers with compact area. The proposed R-LMBA guarantees proper phase differences among the three sub-PAs across the entire operating frequency band without the need for a bulky phase shifter that is adopted in conventional LMBAs. The design equations for the R-LMBA are proposed and analyzed in detail. A proof-of-concept PA has been designed in 0.1 μm GaAs pHEMT process to verify the proposed concept. In Mode-1, from 30 to 40 GHz, it achieves saturated output power (P sat) of 27.7–29.1 dBm with peak power added efficiency (PAE) of 28.5–34.4%, and 16.8–22.1% PAE at 6-dB PBO with its best 1.29 × efficiency enhancement over a Class-B counterpart. In Mode-2, it exhibits 28 dBm P sat with 30% peak PAE, and a PAE of 25%/13.6% at 6-/12-dB PBO, which is 1.67 × /1.81 × over an ideal Class-B PA. Besides, in Mode-1/-2, the PA demonstrates 21.3/20.3 dBm average output power (P avg) and 17.9%/22.1% average PAE (PAE avg) with −28.1/-23.8 dB error vector magnitude (EVM) and −29.1/-25.9 dBc adjacent channel leakage ratio (ACLR) under 6-Gb/s 64-QAM modulated signal at 35 GHz. [ABSTRACT FROM AUTHOR]

This paper presents a new method to enhance the efficiency of a symmetrical doherty power amplifier (DPA) by fully utilizing the current driving capability of a class-C biased peaking amplifier. In this method, with utilization of the passive voltage gain concept, the input matching networks are designed in a way that the peaking path experiences a higher voltage gain than the carrier path, at high powers. As a result, the higher drive voltage of the peaking amplifier compensates for its lower gate bias and identical peak output currents for both amplifiers can be achieved. For demonstration purpose, a two-stage symmetrical DPA with a power utilization factor (PUF) of about unity is designed and fabricated in a standard 0.18- μ m CMOS technology. The measurement results at 2.6 GHz show a power gain of 21 dB and an 1 dB compression point of 21.3 dBm. The peak power added efficiency (PAE) is 35% and the PAE at 6 dB power back-off (PBO) is better than 23%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spoof surface plasmon polaritons (SSPP) theory has been applied to the design of multi-octave RF PA for the first time. • The proposed SSPP PA achieves a 47 % reduction in size compared to the traditional transmission-line based PA. • Bayesian optimization (PSO) is used to enhance the performance of the SSPP PA circuit. • To improve the linearity of the SSPP-based PA, digital pre-distortion (DPD) is implemented for the designed PA. Surface Plasmon Polariton (SSPP), which exhibits subwavelength-scaled field confinement, can be realized at microwave frequencies by ultrathin corrugated metallic strips, providing significant potential for circuit and system miniaturization. A number of SSPP units were employed in this study to design input and output matching networks of a multi-octave RF power amplifier (PA) for the purpose of reducing the overall circuit size. The designed SSPP-based PAs were fabricated and demonstrated to have an output power between 39.1 dBm and 41.8 dBm, and a power added efficiency (PAE) ranging between 60.2 % and 69.8 % in the frequency range of 0.8 GHz to 3.1 GHz, with a size of 35.5 mm * 46.7 mm, which achieves a 47 % size reduction compared to the traditional transmission-line based PA. A highly efficient global optimization method, the Bayesian Optimization (BO), was utilized to further enhance performance. SSPP PA's average output power and PAE have been improved by approximately 0.3 dBm and 2.6 %, respectively. Its overall size remains at the same level. With the use of a 20 MHz 5GNR signal, digital pre-distortion (DPD) has been implemented, and the linearity of the PA has been improved. [ABSTRACT FROM AUTHOR]

• A 71 mJ, 300 Hz mid-infrared source based on ZnGeP 2 MOPA system was reported. • By using the structure of ZGP-OPO combined with two-stage ZGP-OPA, we safely obtained a high-energy mid-infrared laser, and experimentally verified that under the condition of the same output energy, better beam quality could be obtained by multi-stage amplification. • The pump source was a Ho:YAG MOPA system, the corresponding total energy was138.3 mJ and the beam quality factor M2 was 1.25 × 1.34. We demonstrated a 71 mJ mid-infrared ZnGeP 2 (ZGP) master oscillator power amplifier (MOPA) system that operated at the pulse repetition frequency of 300 Hz. A 2090.6 nm electro-optical Q-switched holmium:yttrium–aluminum-garnet MOPA system with a total energy of 138.3 mJ was used as the pump source of the ZGP-MOPA system. First, based on a ZGP optical parametric oscillator, a mid-infrared laser output of 1.3 mJ was obtained in the state of low-energy pumping. The corresponding beam quality factor M2 was 2.01 × 2.10 (horizontal directions × vertical directions). After two-stage amplification, a mid-infrared laser of 71 mJ was obtained. The pump energy and seed energy of the second ZGP optical parametric amplifier were 92.7 mJ and 23 mJ, the corresponding slope efficiency was 70.3 %. At the maximum output energy level, the pulse width of the mid-infrared laser was 14.6 ns, and the beam quality factor M2 was 3.96 × 3.75. [ABSTRACT FROM AUTHOR]

With the proliferation of internet of vehicles (IoV) applications, the information exchange and anti-collision radar become increasingly important for vehicular safety. The fusion of radar and wireless communication, called RadCom, has been proposed for future intelligent transportation. Traditional orthogonal frequency division multiplexing (OFDM)-based RadCom systems, however, suffer from impractical bandwidth allocation and high peak-to-average power ratio (PAPR), which results in not only severe nonlinear distortion but also low efficiency of high power amplifier (HPA). Motivated by these research problems, we propose a new partially-reserved cyclic algorithm for OFDM-based RadCom fusion systems. Our proposed RadCom algorithm is able to allocate appropriate communication bandwidth on the request of actural transmission by assuming that the entire bandwidth can be used for radar detection. In the frequency-domain, when the spectral sub-band for communication is reserved, we optimize over the remaining spectral sub-band by the proposed algorithm for PAPR reduction. The evaluation of the system with the proposed algorithm shows significantly improved performance over traditional OFDM-based RadCom systems in both the communication and radar functions when HPA is taken into account. [ABSTRACT FROM AUTHOR]

This paper presents a novel dual mode configurable and tunable power amplifier (PA) that achieves a wide-bandwidth and high gain across a operational frequency spectrum of 20 to 30 GHz. The proposed PA used two-stage tunable PA which can be configured as a tunable synchronous mode or tunable stagger-tuned mode PA. PA is implemented by using a distortion-free varactor at the input and output tank of PA. The designed PA includes a high-Q CMOS active inductor (CAI) which provides a widely tunable output matching network. The resistive feedback is used for self-biasing in the designed PA which helps to enhance the linearity, stability of common source (CS) amplifier. The inter-stage impedance matching network consists of shunt and series resonance circuits are employed for maximum power added efficiency (PAE). Furthermore, the capacitive coupled reuse technique is implemented in each stage between the cascaded transistor to reduce the power consumption. A proposed PA is designed using a 65 nm CMOS technology. A measured power gain at the synchronous operation of PA is 28.4 ±0.5 dB with 1.31 GHz bandwidth while power gain at staggered operation is 22.1 ±0.5 dB with 3.71 GHz bandwidth. The measured saturated power (P sat) is 14.21 dBm and the noise figure (NF) is 5.2 dB. The group delay (GD) variation for staggered operation is 57 ±10 ps from 20-30 GHz. A proposed PA exhibits good linearity (IIP3) of 14.5 dBm and PAE is 47.5 % at 24 GHz. The power consumption of a designed PA is 48.56 mW with a supply voltage of 1.2 V. [ABSTRACT FROM AUTHOR]

This paper presents a 20-Gb/s automatic gain control (AGC) amplifier in a 0.18-μm SiGe BiCMOS for high-speed applications. The proposed AGC amplifier compactly consists of a folded Gilbert variable-gain amplifier (VGA), a post amplifier (PA), a 50-Ω output buffer, and AGC loop including an open-loop peak detector (PD), a RC low-pass filter (LPF), and an error amplifier (EA). The AGC amplifier achieves the broadband characteristic by utilizing inductive peaking and capacitive degeneration as well as f T -doubler techniques to overcome the large parasitic capacitances. The proposed AGC circuits together with a linear VGA exhibits a wide gain control range of 45 dB for the received signal strength indication (RSSI). The measured AGC amplifier achieves a maximum gain of 21 dB and a -3-dB bandwidth (BW) of 20.6 GHz, which can support up to 25.4-Gb/s data rate. For the pseudorandom bit sequence (PRBS) length 231–1 with a bit-error rate (BER) of 10−12 at 20 Gb/s, the measured input dynamic range is 26 dB (20–400mV pp) and the peak-to-peak data jitter is less than 8 ps. The AGC amplifier consumes a power of 160 mW from a 3.3-V supply voltage and occupies an area of 850 μm × 850 μm. • The proposed 20-Gb/s AGC amplifier consists of VGA, PA, buffer and AGC loop in 0.18-μm SiGe BiCMOS for high-speed link. • Inductive peaking, capacitive degeneration and f T -doubler are utilized to extend the bandwidth (BW). • The proposed AGC circuits together with a linear VGA exhibits a wide gain control range of 45 dB for RSSI. • The measured results show a max gain of 21 dB and a -3-dB BW of 20.6 GHz, a power of 160 mW and an area of 850 μm × 850 μm. • For PRBS31, BER of 10−12 at 20 Gb/s, the measured input dynamic range is 26 dB and the data jitter is less than 8 ps. [ABSTRACT FROM AUTHOR]

For the multiple-input multiple-output (MIMO) downlink employing high-order quadrature amplitude modulation signaling and with nonlinear high power amplifiers (HPAs) at base station transmitter, the existing precoding designs relying on the linear MIMO channel can no longer work. We propose an efficient and accurate predistorter design to enable transmit precoding for nonlinear MIMO downlink. Specifically, we obtain the closed-form least squares estimates of the nonlinear HPA's amplitude and phase response using two B-spline neural networks during training. The estimated HPA's phase response automatically yields the estimate of the predistorter's phase response. Based on the B-spline neural network estimate of the HPA's amplitude response, we construct a B-spline neural network model for the predistorter amplitude response, and we adopt a particle swarm optimization (PSO) algorithm to solve this highly nonlinear optimization problem. Using our accurate predistorter estimate to pre-compensate for the nonlinear distortions of the transmit HPAs, a standard full-digital transmit precoding design can readily be adopted to combat the MIMO channel interference. A simulation study is conducted to demonstrate the effectiveness of our proposed PSO assisted predistorter design. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach to designing a broadband, highly efficient filtering power amplifier (FPA) characterized by unique integrated filtering capabilities. Central to the proposed technique is the utilization of an asymmetrical open-circuit coupled-lines bandpass filter (BPF), serving dual functions as both an input matching network and an output matching network. Notably, this filter design not only enhances the bandpass filtering response but also significantly improves second harmonic rejection performance. To validate this methodology, a broadband FPA is implemented, employing the Cree 10 W GaN HEMT. The proposed FPA, operating between 2.0–3.0 GHz, achieves a peak drain efficiency of 45.9 %-73.26 %, corresponding to a peak output power of 38.5–41.95 dBm at saturation. This marks a notable efficiency enhancement compared to recent research findings. It is believed that the FPA solution is custom-tailored to meet the demanding requirements of modern base stations, striking the balance between improved power-efficiency and good filtering performance. [ABSTRACT FROM AUTHOR]

This paper presents a high efficiency Rat-Race Coupler based compact GaN HEMT power amplifier (PA) design over broadband for high power transmitter in wireless communication. The rat-race coupler integrated PA Compact design is proposed for the first time as per author best knowledge. The design methodology used a higher order two open stubs and a rat-race coupler (RRC) at input/output sections to control harmonics impedances. The RRC is used to enhance the i/o power, and efficiency over broadband, which provides a good insertion loss, and consumes the least power and non-crucial impedance bandwidth for the normalized frequency band of interest. As a proof of concept, a PA is fabricated using a monolithic microwave integrated circuit (MMIC) 0.15 µm gallium nitride high electron mobility transistor (GaN HEMT) process. The measured result shows that the designed PA achieves a flat power added efficiency (PAE) of 65 % − 74 %, output power (P o u t ) of 44.8 dBm − 46 dBm, and drain efficiency (DE) of 72 % − 85 %, over a record wide frequency of 1.8 GHz − 3.6 GHz, which is the highest one among all reported harmonic tuned PAs. [ABSTRACT FROM AUTHOR]

This paper presents a power amplifier (PA) with an 8-way series–parallel power combiner for 5G communication. By theoretical analysis of the S-parameters matrix and the equivalence of the impedance network, the design of the multi-port combiner is transformed into a dual-port on-chip transformer, and the bandwidth expansion is achieved without increasing the in-band gain ripple based on the mismatch-consistent magnetically coupled resonator (MCR) technique. As a validation of the methodology, the 8-way series–parallel power combiner PA is implemented in 40-nm CMOS Bulk process. The large-signal performances of the PA at 31 GHz are 21.36 dBm, 17.1 dBm, and 25.7 % for P sat , OP 1dB , and PAE max , respectively. The proposed PA has a peak S 21 of 25.1 dB and a 3-dB bandwidth of 23.5–46.4 GHz, which fully covers the 5G new radio (NR) frequency range2 (FR2) operating band, and the S 21 ripple is less than 1-dB in the range of 26.0–42.3 GHz, which achieves a broadband flat frequency response and supports the feasibility of the design. [ABSTRACT FROM AUTHOR]

In this work, the automated design of a power amplifier circuit in a 130 nm BiCMOS technology operating in the 220 GHz to 260 GHz frequency range is presented. The design automation process is based on the RapidIP approach, which enables the evaluation, rating and optimisation of thousands of different circuit topologies within only a few minutes. In total 6. 13 ⋅ 1 0 5 optimisation steps and 2. 6 ⋅ 1 0 4 different circuit topologies have been explored within an overall runtime of 23 min. According to post-layout simulations, the amplifier achieves a saturated output power of 9 dBm with a peak power-added efficiency of 2.8% and a 3 dB-bandwidth of 55 GHz. [ABSTRACT FROM AUTHOR]

• The pulse repetition frequency of 1064 nm laser pumped BaGa 4 Se 7 -OPO was first improve to 1 kHz with a master oscillator power amplifier system used as the pump source. The maximum output power at 4.18 μm was 483 mW. • Both temperature and angle tuning of BGSe-OPO were studied and widely tunable output in the range of 3.36–5.16 μm was obtained. • High stability operation of OPO was achieved with average power fluctuation root mean square of 0.98 % in 30 min. In this work, a tunable mid-infrared optical parametric oscillator based on type I phase-matching BaGa 4 Se 7 was demonstrated. Using a Nd:YAG master oscillator power amplifier system as pump source, we firstly achieve the 1064 nm pumped BGSe-OPO at 1 kHz repetition rate. With pump double-pass single resonant oscillator configuration, the maximum output power at 4.18 μm was 483 mW and the corresponding conversion efficiency is 8.78 %. Both temperature and angle tuning of BGSe-OPO were studied and widely tunable output in the range of 3.36–5.16 μm was obtained. The average power fluctuation measured within 30 min was 0.98 % root mean square. This study has unveiled the great potential of BGSe crystal in highly stable, widely tunable, high repetition rate mid-infrared pulse generation. [ABSTRACT FROM AUTHOR]

• We present a broadband nanosecond superfluorescent fiber source (ns-SFS). • The impact of the active fiber' s length on the output spectrum of SFS is investigated theoretically and experimentally. • All-fiberized ns-SFS amplifier with average power of greater than 440 W, pulse energy of 17.6 mJ is achieved. In this work, we demonstrate a broadband nanosecond superfluorescent fiber source (ns-SFS) with an average power of several hundred watts and an adjustable repetition frequency of 25 kHz–100 kHz. To figure out a suitable active fiber length for ns-SFS seed, the impact of active fiber length on the output spectrum of SFS is investigated theoretically and experimentally. The results indicate an evident redshift in the central wavelength of output spectrum with increasing fiber length. By scaling the power of the ns-SFS seed employing three amplifier stages, the maximum average power and pulse energy are obtained with a value of 463 W, 17.6 mJ, respectively. To the best of our knowledge, this work is the first demonstration of a broadband ns-SFS amplifier with output power exceeding hundred watt and pulse energy exceeding 10 mJ. [ABSTRACT FROM AUTHOR]

The performance of offset quadrature amplitude modulation filter bank multi carrier (OQAM-FBMC) has been noticed to be affected by a high peak-to-average power ratio (PAPR). High PAPR causes the transmit power amplifier to become saturated, improving the bit error rate (BER) and causing out of band (OOB) distortions. In this paper, the PAPR of FBMC systems can be reduced by using shifting and scaling the trigonometric companding technique associated with a reduced BER performance and the power spectral density (PSD) with low OOB distortions. The characteristics of low peak signals are not changed by this companding scheme, while the characteristics of high peak signals are transformed into scaling piecewise nonlinear trigonometric functions. By tuning the parameters the suggested technique maintains the average signal power level unchanged. The theoretical analysis of the proposed scheme is also studied and also compared with the simulation results. The performance of the trigonometric companding scheme is also analysed with the μ -law and A-law existing companding methods and the suggested method obtaining 3 dB and 3.2 dB PAPR improvement respectively. The proposed technique determined to be better in terms of BER performance and spectrum efficiency. [ABSTRACT FROM AUTHOR]

• This article realizes the simultaneous output of high-voltage high-frequency excitation for transmission line measurement. • The proposed differential linear cascaded amplifier topology breaks through the limitation of gain bandwidth product. • Designing appropriate isolation voltage for cascaded power supply can meet different testing voltage requirements. • The parallel fiber optic isolation cascade method breaks through the kHz limitation of high-voltage amplifiers. In this paper, a high-frequency and high-voltage linear cascaded amplifier based on parallel optical fiber isolation is proposed. The electro-optical synchronous drive of the excitation signal is realized through equal proportional laser splitting, which achieves the same linear gain and output phase shift in each photoelectric conversion unit. The differential linear cascade topology designed in this paper effectively solves the gain bandwidth product limitation and achieves a high-voltage linear output in a high-frequency range. The new amplifier solves the problem that due to the low AC excitation voltage of traditional impedance analyzer, the signal attenuation is severe in long distance and high insulation distributed electrical parameter network. It can be widely used to measure high-frequency dielectric loss and impedance spectrum for dielectric materials and electrical components in industry and laboratory. By cascading n -stage amplifier units, the voltage gain can reach 6n times. Finally, a 16-stage cascade amplifier is built, and the response characteristics are tested with the distributed electrical parameter network loads. The output characteristics show that the expected amplifier gain can be obtained accurately in the high-frequency range of 100 kHz–100 MHz, the output voltage can reach 192Vpp, and the peak current can reach ±500 mA. The maximum of the curve about THD and noise versus frequency could be limited to 0.49 %, which could meet the needs of on-site measurement. [ABSTRACT FROM AUTHOR]

This paper introduces a novel multi-harmonic resonance approach in designing a single-ended parallel-circuit class – E/F 3 power amplifier (PA). At its core, this innovative design integrates a novel reactance compensation technique with multi-harmonic tuning at the load, to achieve unprecedented wideband characteristics and elevated efficiency. The approach is further distinguished by the strategic incorporation of two distinct LC shunt resonators, each finely tuned to either the second or third harmonic. This unique configuration ensures precise impedance mapping to the optimal values for the device, a critical factor in enhancing PA performance. A key innovation lies in the meticulous attention to third harmonic terminations, which significantly boosts the power-added efficiency, a crucial metric in PA functionality. The design approach is validated using a PCB-based GaN PA from 500-1500 MHz. The measurement results show that the designed class E / F 3 PA has a saturated output power of more than 10 W, power added efficiency of 80.5%, and a power gain of 15.2 dB at an operating frequency of 1000 MHz. [ABSTRACT FROM AUTHOR]

This paper propose an inverted sequential load-modulated balanced amplifier (ISLMBA) for extending the dynamic power range of a power amplifier (PA) over a wide bandwidth. The proposed ISLMBA consists of a control amplifier (CA) and a balanced PA (BPA) pair. A composited impedance inverter is inserted between each BPA transistor and the output coupler. The composited impedance inverter is composed by the intrinsic elements and output matching network (OMN) of the BPA transistor. In this way, the intrinsic elements can be fully absorbed into the impedance inverter over a wide bandwidth. Meanwhile, the load modulation trajectories of the BPA transistors can be optimized over a wide bandwidth by tuning the characteristic impedance of the impedance inverter. The theoretical current, voltage and load-modulation profiles of the ISLMBA are comprehensively analyzed. It is illustrated that the proposed ISLMBA could maintain high efficiency at deep output back-off power level over a wide bandwidth. Moreover, this work designs and fabricates an ISLMBA operating over 1.3–2.55 GHz to verify the proposed PA architecture. The fabricated ISLMBA exhibits a saturation drain efficiency (DE) of 54.5%–73.8% and a saturation output power of 42.9–45.9 dBm. At the same time, the fabricated ISLMBA achieves a 10 dB back-off DE of 42.1%–63.9% over the frequency band of interest. When the fabricated ISLMBA is stimulated by a 20 MHz wideband signal with a peak-to-average power ratio (PAPR) of 10.2 dB at 2.0 GHz, the measured adjacent channel leakage ratios (after predistortion) are −47.7 and −48.8 dBc at the lower and upper bands, respectively. [ABSTRACT FROM AUTHOR]

The higher bit rates, lower noise figure, decreasing the nonlinear penalty of fiber system, longer amplifier length, tight channel spacing and operating near the zero-dispersion wavelength are achieved by using Distributed Raman amplifiers (DRAs). In this paper, a new model of noise figure (NF) due to amplified spontaneous emission (ASE) is introduced for the DRA at different pump schemes: co-pumping, counter-pumping and bidirectional pumping. The variation of power conversion efficiency (PCE) with input pump power; input signal power and amplifier length for S-band is also investigated. It is found that, the NF increases exponentially with the fiber length and decreases exponentially with input signal power, power conversion efficiency (PCE) increases exponentially with the fiber length and input signal power and decreases exponentially with the input pump power. The obtained results show that, the noise figure (NF) reaches its minimum value of 8.6, 9.7 and 11 dB, while the PCE reaches its maximum value of 71%, 31% and 7% in counter-pumping, bidirectional pumping and co-pumping, respectively. [ABSTRACT FROM AUTHOR]

Gallium Nitride shows huge potential in power electronics applications thanks to the superior intrinsic material properties which result in improved performance both at device level and system level. Great effort has been taken in recent years to industrialize GaN technology and to solve some of the major drawbacks like reliability issues and dynamic effects. The goal of this work is to propose a novel methodology to analyse the role of these phenomena on the end application efficiency. These insights can thus lead to a system-level driven optimization of GaN technology. We propose a method based on T-CAD mixed-mode simulation and we give an example of its implementation in the analysis of a class-E power amplifier for wireless power transfer. Efficiency curve is extracted for different load resistance values. This is carried out for the device both in relaxed and in stressed conditions to evaluate the impact of buffer traps. It is demonstrated how the main degradation resides in the increased dynamic resistance while threshold voltage shift and output capacitance variations both play a minor role. A method to calculate the dynamic resistance evolution during the switching cycles is then outlined. At the design point the resistance is expected to fully recover to the nominal value. [ABSTRACT FROM AUTHOR]