Power Amplifier Research Articles

Analysis and design of broadband Doherty power amplifier using parameterized load modulation network and complex combining load

This paper presents a novel approach to design broadband Doherty power amplifiers (DPAs) with extended fractional bandwidth (FBW). A parameterized load modulation network (LMN) and complex combining loads are proposed that can extend the FBW while providing more accurate back-off impedance. To examine the influence of parameter variations in the LMN on the broadband performance of the DPA, we utilize the parameter scanning method and subsequently select the optimal parameters in the LMN. Additionally, three-dimensional computer visualization techniques is invoked to visually examine the impedance solution space of the complex combining loads. A DPA prototype with a bandwidth of 0.85–1.8 GHz is then designed and implemented using commercial GaN transistors to validate the proposed architecture. The fabricated DPA attains a measured gain of 14.2–15.7 dB and a saturated power of 43.0–44.9 dBm. Across the designed operation band, the measured drain efficiency reached 51.6%–73.6% at saturation and 43.7%–56.7% at 6 dB output power back-off. When driven by a 20 MHz modulated signal with a peak-to-average power ratio (PAPR) of 8 dB, the average efficiency of the fabricated DPA is higher than 46.7%.

Broadband dual-input doherty power amplifier design based on a simple adaptive power dividing ratio function

Broadband dual-input doherty power amplifier design based on a simple adaptive power dividing ratio function

Design of class f reconfigurable power amplifiers

With the rapid development of mobile communication technology, RF amplifier requirements becoming higher, miniaturization, high efficiency and multi-band have gradually become a research hotspot. Based on these hot research directions, this paper designs a dual-band reconfigurable power amplifier. The input of the amplifier adopts a stepped impedance matching network, which has a good matching effect in the 1.6 - 2.8 GHz band. The output is switched by a single-knife double-throw switch to the corresponding band output matching network to achieve the fast switching of different frequency bands. The RF amplifier tube is designed by using Cree’s GaN chip CGH40010F, which has an additional power efficiency of more than 60% in the frequency range of 1.7 - 1.9 GHz and 2.5 - 2.7 GHz bands, a gain of about 12 - 14 dB and a saturated output power of more than 40 dBm. This design has the features of high efficiency, high gain, miniaturization and multi-band, which is applicable to the mobile communication system.

A Scalable Bandwidth and Frequency-Dependent DPD Linearizer for User Equipment Power Amplifiers With Nonflat Frequency Response

A Scalable Bandwidth and Frequency-Dependent DPD Linearizer for User Equipment Power Amplifiers With Nonflat Frequency Response

High-Efficiency High-Linearity Power Amplification Technique by Digital-Assisted Injection-Control Matching for 6G Flexible Spectrum Applications

High-Efficiency High-Linearity Power Amplification Technique by Digital-Assisted Injection-Control Matching for 6G Flexible Spectrum Applications

Design and Development of GaN-Based Power Amplifier for Radar Applications

This paper presents a comprehensive overview of Gallium nitride (GaN)-based power amplifier (PA) design for various frequency bands. GaN-based technology has emerged as a promising alternative to traditional silicon-based amplifiers due to its superior performance characteristics, which are discussed in this paper. This paper also discusses the key design parameters and challenges associated with PA design. Various design techniques and topologies for GaN power amplifiers are explored besides addressing theoretical considerations of PA design along with a complete systematic design procedure for L-Band amplifier using the wolfspeed large signal GaN HEMT model. To further demonstrate the useful methodology, the designs of S-band and C-band PAs are also presented. GaN-based devices are very promising candidates for high-power applications. It is widely used in various high-power applications including communication and radar.

Design of a Compact 2-6 GHz High-Efficiency and High-Gain GaN Power Amplifier.

In this paper, a novel wideband power amplifier (PA) operating in the 2-6 GHz frequency range is presented. The proposed PA design utilizes a combination technique consisting of a distributed equalization technique, multiplexing the power supply network and matching network technique, an LR dissipative structure, and an RC stability network technique to achieve significant bandwidth while maintaining superior gain flatness, high efficiency, high gain, and compact size. For verification, a three-stage PA using the combination technique is designed and implemented in a 0.25 μm GaN high-electron-mobility transistor (HEMT) process. The fabricated prototype demonstrates a saturated output power of 4 W, a power gain of 21 dB, a gain flatness of ±0.6 dB, a power-added efficiency of 39-46%, and a fractional bandwidth of 100% under the operating conditions of drain voltage 28 V (continuous wave) and gate voltage -2.6 V. Moreover, the chip occupies a compact size of only 2.51 mm × 1.97 mm.

Design and experimental validation of class-[formula omitted] GaN power amplifier using a compact harmonic control unit

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.

Enhanced performance of Ku-band GaN MMIC PA through embedded microfluidic cooling

The impact of embedded microfluidic cooling on the performance of Ku-band gallium nitride (GaN) microwave monolithic integrated circuit (MMIC) power amplifiers (PAs) has been studied in this work. The research demonstrates that embedded cooling can substantially lower junction temperatures, mitigate the self-heating effect, and thereby improve the electrical performance of GaN MMIC PAs. Using merely 10.4 mW of pumping power (Ppump), the technology reduces the maximum junction temperature (Tj,max) from 216.7 to 147.8 °C. Furthermore, the system enhances the saturation current by 13.8%, increases output power (Pout) and gain (Gain) by 1.8 dB, elevates the power added efficiency (PAE) by 5.9%, and improves the heat flux of last gate (Qgate) to 37.3 kW/mm2 and the heat flux of MMIC (QMMIC) over 2.6 W/mm2, while reducing the thermal resistance (Rj-c) from 2.13 to 1.26 °C/W. Additionally, there is a notable improvement of the small signal gain (S21) by 2.5 dB. Therefore, the achievements in this work indicate that embedded cooling offers a powerful technique to suppress the thermal effects on GaN MMIC PAs, consequently improving their electrical performance.

A Ka-band 27.6-dBm power amplifier with a compression-state large-signal matching approach in 130-nm CMOS SOI technology

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 (Psat) of 27.6 dBm with 14.1 % peak power added efficiency (PAE), output 1-dB compression point (OP1dB) 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.

Design Techniques for Wideband CMOS Power Amplifiers for Wireless Communications

In this study, we designed a wideband CMOS power amplifier to support multi-band and multi-standard wireless communications. First, an input matching technique through LC network and a wideband design technique using a low Q-factor transformer were proposed. In addition, a design technique was proposed to improve output matching using RC feedback. To verify the feasibility of the proposed design methodology for wideband CMOS power amplifiers, the designed power amplifier was fabricated using a 180 nm RFCMOS process. The size including all of the matching network and test pads was 1.38 × 0.90 mm2. In addition, the effectiveness of the proposed power amplifier was verified through the measured results using modulated signals of WCDMA, LTE, and 802.11n WLAN.

Design, Implementation and Performance Analysis of RF Power Amplifier for 5G Mobile Communication in the Sub-6 GHz Band Using Advanced Node 18nm FinFET Technology

Design, Implementation and Performance Analysis of RF Power Amplifier for 5G Mobile Communication in the Sub-6 GHz Band Using Advanced Node 18nm FinFET Technology

Power Amplifier Modeling Framework for Front-End-Aware Next-Generation Wireless Networks

Next-generation wireless systems require increased spectral and energy efficiency in terminals. This can only be achieved if the nonlinear characteristics of the radio front-end, primarily the power amplifier (PA), are known and considered while designing algorithms or optimizing radio links. PA datasheets contain limited information, and wideband PA measurements typically require advanced equipment and software. This paper proposes a measurement and signal processing framework that enables the acquisition of nonlinear PA characteristics using generic complex sample transmitters and receivers, e.g., software-defined radio (SDR). This paper also proposes a multistage signal calibration and synchronization procedure that allows obtaining nonlinear PA characteristics that are non-distorted by other phenomena. The correctness and usefulness of the proposed framework are demonstrated by measuring three PAs, each under varying supply voltage and carrier frequency. At the same time, the high variability of the obtained nonlinear characteristic justifies the need for PA measurements to obtain awareness of nonlinear characteristics.

RF circuit techniques for transition to 5G advanced

Abstract Worldwide adoption of 5G mobile devices has been one of the main driving engines behind semiconductor industry. Since the initial release in 2020, 5G-enabled devices have surpassed the market penetration of 3G/4G smartphones. 5G brings higher data capacity, low latency, and new applications. These are possible due to lower feature nodes such as FinFET 3 nm/5 nm but also due to improvements of the 5G radio frequency (RF)front-end circuitry. This paper presents 5G RF front-end architectures with novel circuits and measurement details which will be part of future 5G advanced and 6G mobile devices and are easier to be controlled using digital circuitry. The paper presents an envelope-controlled power amplifier (PA) principle, along with a novel simplified calibration architecture designed for 5G/5G+ operating under 6 GHz, as well as for frequency range 2 millimeter-wave PAs. An earlier version of this paper was presented at the 2023 53rd European Microwave Conference and was published in the Proceedings [Balteanu F, Thoomu K, Pingale A, Venimadhavan S, Sarkar S, Choi Y, Modi H, Drogi S, Lee J and Agarwal B (2023) Enabling RF circuit techniques for 5G and beyond In 53rd European Microwave Conference (EuMC), Berlin, Germany, 22–25].

RESEARCH OF STRUCTURAL AND MECHANICAL PROPERTIES OF MEAT AS AN OBJECT OF PROCESSING IN MEAT COMMINUTOR

Reliable assessments of the state of modern energy show the relevance of scientific and technical developments aimed at solving its problems. In this regard, the use of resonance phenomena in electrical circuits with active-reactive elements acquires particular significance. Their various combinations open up exceptional opportunities for creating fundamentally new efficient energy sources. This article discusses a resonant active electrical power amplifier containing a sequence of several electrically connected active-reactive circuits, which, depending on the purpose, are excited in the voltage resonance or current resonance mode. An equivalent circuit is proposed for the proposed resonant amplifier of active electrical power, represented by two blocks, each of which consists of a sequence of inductively coupled active-reactive circuits excited at the same frequency. Calculations are presented showing the theoretical justification for the performance of the proposed scheme. The analysis of ongoing electromagnetic processes was carried out using well-known methods of the theory of electrical circuits without involving any hypotheses about the physics of resonance phenomena. It is shown that in the proposed amplifier circuit, the first block amplifies the reactive power of the harmonic signal with a high conversion coefficient, the second, with a slight gain, converts the reactive power of the harmonic signal into active power. The results of calculations are presented, illustrating the functional dependence of the integral gain on the main characteristics of the output resonant circuit. Numerical estimates of the main characteristics of the proposed circuit showed that with an appropriate choice of its parameters, high values of the output characteristics are possible, so the gain can reach a value of ~ 48. The significance of the results obtained for practice lies in their use for formulating recommendations for the creation of real efficient sources of electrical energy, the principle whose actions are based on the use of natural resonance phenomena.

Design of Broadband Doherty Power Amplifier Based on Misaligned Current Phase

A broadband Doherty power amplifier (DPA) always experiences an efficiency degradation between two efficiency peaks, especially at two side bands. In this study, the efficiency degradation was demonstrated to be caused caused by the in-phase power combining at the saturation power level. To solve this problem, current misalignment was introduced into the broadband DPA design. The carrier and peaking PA have different current phases when performing the power combination at the saturation power level. In this work, it was also demonstrated that the efficiency in the high-power region of a DPA can be improved by elaborately using misaligned current phases. A detailed analysis and the design procedure of a broadband DPA are presented in this paper. And a 1.5–2.45 GHz broadband DPA was implemented and measured. The fabricated DPA achieves a saturation output power of 42.7–44.9 dBm, a saturation drain efficiency (DE) of 62.7–74.1% and a gain of 10.2–13.9 dB over 1.5–2.45 GHz. Moreover, the fabricated DPA also achieves a 6 dB back-off DE of more than 49.1% in the frequency band of interest.

Efficient Constant Envelope Precoding for Massive MU-MIMO Downlink via Majorization-Minimization Method.

The practical implementation of massive multi-user multi-input-multi-output (MU-MIMO) downlink communication systems power amplifiers that are energy efficient; otherwise, the power consumption of the base station (BS) will be prohibitive. Constant envelope (CE) precoding is gaining increasing interest for its capability to utilize low-cost, high-efficiency nonlinear radio frequency amplifiers. Our work focuses on the topic of CE precoding in massive MU-MIMO systems and presents an efficient CE precoding algorithm. This algorithm uses an alternating minimization (AltMin) framework to optimize the CE precoded signal and precoding factor, aiming to minimize the difference between the received signal and the transmit symbol. For the optimization of the CE precoded signal, we provide a powerful approach that integrates the majorization-minimization (MM) method and the fast iterative shrinkage-thresholding (FISTA) method. This algorithm combines the characteristics of the massive MU-MIMO channel with the second-order Taylor expansion to construct the surrogate function in the MM method, in which minimizing this surrogate function is the worst-case of the system. Specifically, we expand the suggested CE precoding algorithm to involve the discrete constant envelope (DCE) precoding case. In addition, we thoroughly examine the exact property, convergence, and computational complexity of the proposed algorithm. Simulation results demonstrate that the proposed CE precoding algorithm can achievean uncoded biterror rate (BER) performance gain of roughly 1dB compared to the existing CE precoding algorithm and has an acceptable computational complexity. This performance advantage also exists when it comes to DCE precoding.

Ultra-Wideband Transformer Feedback Monolithic Microwave Integrated Circuit Power Amplifier Design on 0.25 μm GaN Process.

This paper presents an ultra-wideband transformer feedback (TFB) monolithic microwave integrated circuit (MMIC) power amplifier (PA) developed using a 0.25 μm gallium nitride (GaN) process. To broaden the bandwidth, a drain-to-gate TFB technique is employed in this PA design, achieving a 117% relative -3 dB bandwidth, extending from 5.4 GHz to 20.3 GHz. At a 28 V supply, the designed PA circuit achieves an output power of 25.5 dBm and a 14 dB small-signal gain in the frequency range of 6 to 19 GHz. Within the 6 to 19 GHz frequency range, the small-signal gain exhibits a flatness of less than 0.78 dB. The PA chip occupies an area of 1.571 mm2. This work is the first to design a power amplifier with on-chip transformer feedback in a compound semiconductor MMIC process, and it enables the use of the widest bandwidth power amplifier on-chip transformer matching network.

Design of a wideband, highly efficient FPA using an asymmetrical open-circuit coupled-lines-based filtering matching network

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.

Multi-mode stable, high peak power Nd:YAG laser device for laser cleaning

High average power and peak power solid-state lasers are of great interest in the field of laser cleaning. In this research, a high peak power laser with over 400 W average power using a multi-mode stable resonator in a diode-pumped Nd:YAG master oscillator power amplifier has been demonstrated. A maximum peak power over 1.08 MW was achieved at a repetition frequency of 5 kHz. Delivery fiber with a 400 µm core diameter was utilized for flexible laser transmission. A prototype of the laser cleaning system was developed and inspiring application effects for paint and mold cleaning were achieved.